MOTOR VEHICLE WITH AIR CONDITIONING CIRCUIT HAVING A HEAT EXCHANGER WITH PHASE CHANGE MATERIAL

Description

Title Motor vehicle WITH AIR CONDITIONING CIRCUIT having a HEAT EXCHANGE WITH PHASE CHANGE MATERIAL MOTOR VEHICLE WITH AIR CONDITIONING CIRCUIT HAVING ONE HEAT EXCHANGER WITH PHASE CHANGE MATERIAL 'k 'k 'k TECHNICAL SECTOR The invention generally relates to a motor vehicle and more specifically to its air conditioning circuit. EARLY ART Motor vehicles may, as is well known, include one or more air conditioning circuits for conditioning the air in the passenger compartment or for cooling heat-generating components in use, such as batteries, particularly in the case of hybrid electric or fully electric motor vehicles. Air conditioning circuits may circulate fluids that do not substantially change phase along their cyclic path, as in the case of common engine cooling circuits for motor vehicle propulsion, in which, for example, a liquid coolant (engine cooling water) circulates, or they may include the typical components for creating a refrigeration cycle, as in the case of the air conditioning circuit in the passenger compartment, in which a refrigerant fluid circulates that changes phase during the cycle, where typical components specifically include at least one compressor, a condenser, a throttle valve, and an evaporator. In some cases, the refrigerant from the refrigeration cycle can be used in an evaporator to cool additional refrigerant that does not change phase along its path. Although generally satisfactory, known automotive air conditioning circuits have drawbacks for which improvement is sought. For example, a first rather general drawback may consist in the fact that the components of the cooling circuits must be oversized to operate effectively even under peak thermal load conditions, although such conditions occur much less frequently than under medium thermal load conditions. A further drawback, this time much more specific and typical of refrigeration cycles in a motor vehicle for air conditioning the passenger compartment, occurs when the refrigeration cycle operates under low load conditions for prolonged periods (low compressor flow rate). In this case, the compressor may enter a pumping condition requiring emergency intervention on the air conditioning circuit to avoid irreversible damage to the compressor. The emergency intervention can typically consist of opening a bypass line in parallel to the compressor which forms respective nodes upstream and downstream of the compressor with a point immediately upstream of it, or in implementing a strategy of switching the compressor off and on at regular intervals and in alternating sequence, with an evident overall inefficiency and ineffectiveness of the air conditioning circuit in both circumstances. In light of the above, there is a need to address at least one of the aforementioned drawbacks. One aim of the invention is to respond to this need, preferably in a simple and repeatable manner. DESCRIPTION OF THE INVENTION The purpose is achieved by a motor vehicle as defined in claim 1. The dependent claims define particular embodiments of the invention. BRIEF DESCRIPTION OF THE DRAWINGS In the following, an embodiment of the invention is described for a better understanding thereof by way of a non-limiting example and with reference to the attached drawings, in which - Figure 1 is a perspective view of a motor vehicle comprising an air conditioning apparatus according to the invention, - figure 2 is a schematic section of a - 3 air conditioning unit heat exchanger, - Figure 3 is a close-up of a detail of an area of ​​the heat exchanger in Figure 2 equipped with schematically represented fins, - figures 4-5 are schematic sections representing respective construction alternatives of the heat exchanger of figure 2, - figures 6-7 are block diagrams representing the arrangement of the components of respective variants of the air conditioning apparatus, according to an embodiment of the invention, - figures 8-9 are block diagrams representing the arrangement of the components of respective variants of the air conditioning apparatus, according to a further embodiment of the invention, - Figure 10 is a block diagram representing the arrangement of the components of the air conditioning apparatus, according to a further embodiment of the invention, - figure 11 is a graph with axes respectively representing the flow rate and compression ratio of an air conditioning compressor, where a pumping line is represented, - Figure 12 is a graph showing the time trend of a temperature of a component or area of ​​the motor vehicle by applying a prior art anti-surge control strategy of the compressor when the air conditioning system includes a heat exchange element to condition the component or area, and - Figure 13 is a graph similar to that of Figure 12 but referring to the application of an anti-pumping control strategy of the compressor feasible by means of the air conditioning apparatus according to the invention. FORMS OF IMPLEMENTATION OF THE INVENTION In figure 1, the reference number 1 is used to indicate, as a whole, a vehicle, specifically a motor vehicle, particularly of a sports or racing type. Motor vehicle 1 comprises at least one passenger compartment, not illustrated, to accommodate a driver and possibly one or more passengers. Furthermore, the motor vehicle 1 may also comprise a plurality of devices U, including for example one or more electrical devices, a propulsion engine, and the like, which generate heat during their operation and may therefore require cooling. Without loss of generality, examples of electrical devices can be an electric motor, power electronics elements, control units, capacitors, batteries, and the like. The motor vehicle 1 includes one of the air conditioning devices 100 (figures 6, 7), 200 (figures 8, 9), 300 (figure 10) to condition the passenger compartment and / or the U devices. The apparatus 100 comprises a conditioning circuit 101 configured to cyclically circulate a conditioning fluid or refrigerant fluid, in particular a cooling fluid and more particularly a conditioning liquid or a cooling liquid, for example water, possibly with the addition of an additive, such as glycol, i.e. an aqueous solution or aqueous compound, along a closed loop or more simply closed path 102. In particular, the circuit 101 includes a pump 104 to circulate the coolant along the path 102. In other words, the coolant circulates through circuit 101 along path 102 in a cyclical manner, that is, repeating path 102 several times, more precisely without ever leaving circuit 101, at least ideally, that is, unless there are micro-leaks in circuit 101 or other problems associated with maintenance or malfunctions — 6 — of circuit 101, or even unless the coolant is voluntarily refilled or replaced. The circuit 101 comprises on the path 102 a heat exchanger or more specifically a radiator 103 to expose the coolant to a heat exchange with another conditioning fluid or refrigerant fluid external to the circuit 101, in this case a gas, in particular air, more specifically coming from outside the motor vehicle 1. Here, the coolant releases heat to the air as it passes through the radiator 103, thus cooling it. Therefore, the radiator 103 has the function of cooling, or more generally, conditioning, the coolant. The circuit 101 comprises on the path 102 one or more zones or points arranged in series or in parallel with each other, in which the coolant respectively comes into thermal contact with the devices U, which are therefore arranged to come into thermal contact with the coolant at the respective points. Furthermore, the circuit 101 comprises on the path 102 a heat exchanger 105 comprising a material confined in a closed thermodynamic system or more simply in a closed volume, arranged to come into thermal contact with the cooling liquid, and - 7 adapted to switch between a solid and a liquid phase only when the temperature of the coolant in thermal contact with the material satisfies a relationship with a phase change threshold. In particular, the material passes from the solid phase to the liquid phase (liquefies) or vice versa (solidifies) when the temperature of the coolant exceeds or is below the phase change threshold, respectively. In this way, the phase transition of the material determines a heat exchange between the material and the coolant based on a latent heat of the material. In practice, the material is more precisely a phase change material. In the embodiment of Figures 6, 7, the heat exchanger 105 is arranged downstream of the radiator 103 according to the path 101. More specifically, in the variant of figure 6, the exchanger 105 is arranged in series with respect to the radiator 103. In the variant shown in Figure 7, the circuit 101 comprises a main branch 106 and a heat exchange branch 107 arranged in parallel to each other. The heat exchange branch 107 comprises the heat exchanger 105; in other words, the heat exchanger 105 is located in correspondence with the heat exchange branch 107. Still referring to the variant of figure 7, the circuit 101 comprises a valve device 108 controllable to selectively allow and prevent the passage of the coolant through the heat exchange branch 107. In other words, the valve device 108 is controllable to selectively open and close the heat exchange branch 107 to the passage of the coolant. When the heat exchange branch 107 is closed, the valve device 108 prevents the passage of the coolant through the heat exchange branch 107, so that the coolant passes entirely through the main branch 106. Conversely, the coolant passes at least partially through the heat exchange branch 107 and therefore through the exchanger 105 when the passage of the coolant is allowed by the valve device 108 or the heat exchange branch 107 is opened via the valve device 108. When coolant is admitted through heat exchange branch 107 (open), valve device 108 may be controlled to divide the coolant between main branch 106 and heat exchange branch 107, or to prevent the passage of coolant through main branch 106, so that the coolant passes entirely through heat exchange branch 107. Here, for simplicity, the valve device 108 is shown as a three-way valve arranged at a node formed by the branches 106, 107 upstream of the heat exchanger 105. However, the three-way valve of Figure 7 is only a non-limiting example, as the valve device 108 can be constructively realized in many ways, for example by means of a plurality of valves arranged at the branches 106, 107, to perform the functions described above. In the embodiment of Figures 6 and 7, the phase-change material liquefies, that is, it changes from the solid phase to the liquid phase, when the temperature of the coolant passing through the heat exchanger 105 exceeds the phase-change threshold. Through liquefaction, the phase-change material removes heat from the coolant, thereby cooling the coolant. For example, in the embodiment of Figures 6, 7, the phase change material may comprise or consist of a paraffin, a hydrated salt, or a sugar alcohol. In the embodiment of Figures 6, 7, for example, the coolant temperature can vary substantially between 60° and 90°. The heat exchanger 105 contributes with the radiator 103 in cooling the coolant in cases of thermal load peaks, i.e. when the U devices generate peaks of heat transferred to the coolant. According to variants not illustrated, the heat exchanger 105 can be arranged upstream of the radiator 103 and downstream of the thermal contact points between the coolant and the devices U. The heat exchanger 105 can for example be constructed according to the scheme of figure 2, where the phase change material is divided into a plurality of layers 2 stacked together according to a rectilinear direction A and interspersed with layer-shaped ducts 3 for the passage of the coolant according to the path 102. As visible in figure 3, a plurality of fins 4 may extend externally to the ducts 3 from the walls defining the ducts 3 so as to sink into the phase change material, i.e., the layers 2, to increase the heat exchange area between the coolant and the phase change material. Alternatively, as in Figure 4, the heat exchanger 105 could comprise two concentric tubes 5, 6, so as to define a first volume internal to the innermost of the tubes 5, 6, and a second volume defined radially between them, where one of the first and second volumes defines a conduit for the coolant, while the other contains the phase change material. The apparatus 200 comprises a conditioning circuit 201 that is similar to the circuit 101 in that it cyclically circulates a conditioning fluid or refrigerant, such as water, along a closed-loop path 202, possibly with the addition of an additive, such as glycol. The refrigerant may, in particular, but not necessarily, be a coolant or conditioning fluid. The conditioning circuit 201 includes components similar to those of the circuit 101, so these components will be described only in terms of what distinguishes them from the corresponding ones and will be indicated, where possible, by a reference number with one hundred more than the corresponding ones. The circuit 201 includes along the path 202 an evaporator 210 which is also part of a further conditioning circuit 211 configured to circulate a further conditioning fluid or refrigerant fluid (which, specifically, changes phase during its circulation in the circuit 201) cyclically along a closed loop path 212. The additional refrigerant fluid, which specifically changes phase in circuit 201, will hereinafter be more simply referred to as the refrigerant. The evaporator 210 is therefore arranged along the path 212, which is preferably distinct and separate from the circuit 201, so that the refrigerant and the coolant exchange heat with each other at the evaporator 210, but specifically do not mix with each other. In other words, the respective sections of the circuits 201, 211 at the evaporator 210 are in thermal contact with each other. In detail, the refrigerant evaporates by coming into thermal contact with the coolant at the evaporator 210, whereby the coolant transfers heat to the refrigerant, thus cooling itself. With reference to the variants of figures 8, 9, the heat exchanger 205, corresponding or similar to the heat exchanger 105 of the circuit 101, is here arranged along the path 202 upstream of the radiator 203, corresponding or similar to the radiator 103 of the circuit 101. Furthermore, in particular, the pump 204 corresponds or is similar to the pump 104 of the circuit 101. In the variant of figure 8, the heat exchanger 205 is arranged along the path 202 downstream of the evaporator 210. In the variant of Figure 9, the heat exchanger 205 is integrated with the evaporator 210. In other words, the heat exchanger 205 integrated with the evaporator 210 more generally defines a heat exchange assembly configured to place the phase change material, the coolant, and the refrigerant all in thermal contact with each other. In greater detail, the heat exchange assembly defines one or more first conduits 10 forming part of the circuit 201 for the coolant and one or more second conduits 11 forming part of the circuit 211, where the first and second conduits 10, 11 pass through the phase change material or are surrounded by the phase change material. In this way, the triple heat exchange between the phase change material, the coolant, and the refrigerant can occur. For example, Figure 5 schematically illustrates a possible constructional embodiment of the heat exchanger 205, where the ducts 10, 11 are interspersed with each other and with layers 12 of the phase change material. In particular, the layers 12 and the ducts 10, 11 (having a layer shape) are stacked with each other in an alternating manner according to a rectilinear direction B. More specifically, each of the ducts 10, 11 is located between two layers 12 according to the rectilinear direction B. In the embodiment shown in Figures 8 and 9, the phase-change material solidifies, that is, changes from the liquid phase to the solid phase, when the temperature of the coolant passing through the exchanger 205 is below the phase-change threshold. Through solidification, the phase-change material releases heat to the coolant, thereby heating the coolant. Then, when the phase-change material is in the solid phase, the same material liquefies when the temperature of the coolant passing through the exchanger 205 exceeds the phase-change threshold. Through liquefaction, the phase-change material removes heat from the coolant, thus providing additional cooling to the coolant, in addition to that obtained by passing through the evaporator 210. For example, in the embodiment of Figures 8, 9, the phase change material may comprise or consist of water, a saline solution, or a paraffin. In the embodiment of figures 8, 9, for example, the coolant temperature can vary substantially between -5° and 20°. The radiator 203 can be used to condition the passenger compartment or more generally an environment of the vehicle 1. In other words, radiator 203 exposes the coolant to heat exchange with the interior air. Here, the coolant passing through radiator 103 extracts heat from the interior air, thus warming itself. The radiator 203 is not essential, so it could be absent in the embodiment of figures 8, 9. The circuit 211 passing through the evaporator 210 is configured so as to create a refrigeration cycle, in particular a Kelvin or compression type refrigeration cycle, so that the circuit 211 includes along its path 212 - a compressor 213 configured to compress the refrigerant, - a condenser 214 arranged downstream of the compressor 213 and configured to condense the refrigerant compressed by the compressor 213 by heat exchange with a further fluid, for example air or a coolant conveyed through the condenser 214, - at least one throttling valve or expansion valve 215 arranged downstream of the condenser 214 and configured to generate a pressure drop across the refrigerant condensed by the condenser 214, and - the evaporator 210 arranged downstream of the expansion valve 215, in particular immediately or directly, and configured to evaporate the refrigerant passed through the expansion valve 215 by heat exchange with the coolant of the circuit 201, thus removing heat from the coolant itself. The U devices may also be arranged here in thermal contact with the coolant at respective points or zones of the circuit 201 downstream of the heat exchanger 205. The points could preferably be arranged upstream of the radiator 203 or downstream of it. The 300 device is similar to the 200 device, so it will be described only in terms of what distinguishes it from the 200 device. Wherever possible, the same reference numbers increased by one hundred will be used to indicate components similar to those of the 200 device. In apparatus 300, circuit 301 (corresponding to or similar to circuit 201 of apparatus 200) could be absent and, for example, replaced by a controllable device for heating the phase-change material of heat exchanger 305 (corresponding to or similar to heat exchanger 205 of apparatus 200), in particular when the phase-change material completely solidifies, i.e., passes from the liquid phase to the solid phase, so as to liquefy the phase-change material, i.e., cause the passage from the solid phase to the liquid phase. In practice, as will become clearer below, circuit 301 could have the function of causing the liquefaction of the phase-change material after the latter has completely solidified. Unlike circuit 201, circuit 301 has two branches 320, 321 in parallel with each other and passing through evaporator 310 (corresponding or similar to evaporator 210 of apparatus 200) and heat exchanger 305, so that the coolant can exchange heat with the refrigerant and the phase change material respectively. An example of a constructional embodiment of the heat exchanger 305 may be the one depicted in figure 5, which is not described again here for reasons of brevity. Furthermore, the circuit 301 includes a valve device 322 that can be controlled to selectively allow and prevent the passage of the coolant through the branch 321, so that it can and cannot respectively pass through the heat exchanger 305. The valve device 322, like the valve device 108, is schematically represented in Figure 10 as a three-way valve, but this is only a non-limiting example. Therefore, the same considerations already made for the valve device 108 apply, in terms of function and structure. Like circuit 201, circuit 310 includes radiator 303 (corresponding to or similar to radiator 203) and preferably pump 304 (corresponding to or similar to pump 204) along path 302 (corresponding to or similar to path 202). Circuit 311, like circuit 211 of apparatus 200, includes compressor 313, condenser 314, throttle valve 315, and evaporator 310 (corresponding to the components of the refrigeration cycle of circuit 211), along its path 312. Unlike the specific circuit 211, the circuit 311 comprises two branches 323, 324 arranged in parallel with each other and comprising or passing respectively through the heat exchanger 305 and the group defined by the expansion valve 315 and the evaporator 310. Furthermore, the circuit 311 includes a valve device 325 controllable to selectively allow and prevent a passage of the refrigerant through the branch 323, and hence through the heat exchanger 305. On the valve device 325, the same considerations apply as on the valve devices 108, 322, in - 19 terms of structure and function. In further detail, the apparatus 300 includes an ECU control unit configured to determine the onset of a pumping state or near-pumping condition of the compressor 313. More precisely, the pumping state or near-pumping condition of compressor 313 is defined by a region or (algebraic) space or domain 328 on a map, particularly two-dimensional, for which a Cartesian plane, of (i.e. defined by) two of the following operating quantities of compressor 313: flow rate processed by the compressor, compression ratio of compressor 313 (ratio between pressure downstream and upstream of compressor 313), and refrigerant temperature, particularly at the outlet of compressor 313. More precisely, the pumped state zone is defined by a boundary 326, also called the pumping line, on the map. The pumping phenomenon occurs in the pumped state, corresponding to a zone 328 on the map where the flow rate is relatively low, while the temperature and compression ratio are relatively high. The near-pumping condition zone is also defined by a relative boundary 327, located in a region of the map where (qualitatively) the flow rate is a little higher, while the temperature and compression ratio are a little lower than at the pumping line (boundary 326). Figure 11 illustrates an example of the map, where the map axes, which specifically define the Cartesian plane, are defined by the flow rate and the compression ratio, respectively. Additional lines 329 on the map identify points on the map with equal temperatures. In the map in Figure 11, boundary 327 is further to the right than boundary 326. Zone 328 is to the left of boundary 326 or 327. Consequently, when two of the three operating quantities mentioned define a point on the map within the zone 328 defined by the boundary 326 or 327, the pumping state or near-pumping condition occurs or arises and can be determined by the ECU control unit. In particular, the ECU control unit can determine the onset of the pumping state or the condition close to pumping by extracting information on two of the three operating quantities mentioned from signals measured by transducers 330, 331, 332 of the apparatus 300 and indicative of the same two operating quantities. For example, transducers 330, 331 are configured to measure pressure signals upstream and downstream of compressor 313, so that the ECU control unit can determine the compression ratio from the information extracted from the signals. Independently, the transducer 332 is configured to measure a signal indicative of temperature, particularly at the output of the compressor 313. For example, the pair of transducers 330, 331 or the transducer 332 may be replaced by a flow meter or more generally by a transducer configured to measure a signal indicative of flow rate. The ECU control unit checks using the extracted information whether the operating point of compressor 313 defined by the values ​​of the two operating variables falls within zone 328 and, if so, determines the onset of the pumping state or the condition close to pumping. The ECU control unit is configured to perform a first control of the valve device 325 to allow the passage of coolant through the branch 323, and then through the heat exchanger 305 when the onset of the pumping state or near-pumping condition is determined, i.e., in response to the determination of the onset itself. Otherwise, the ECU controls the valve device 325 to prevent the coolant from passing through the branch 323, i.e. to prevent the coolant (even partially) from reaching the heat exchanger 305. In particular, the first control commands the valve device 325 to distribute the refrigerant between the evaporator 310 and the exchanger 305, i.e. between the branches 323, 324. In this way, the phase change material of the heat exchanger 305 solidifies, releasing heat to the portion of the refrigerant passing through the heat exchanger 305. Therefore, overall, the refrigerant upstream of the compressor 313 is heated. In other words, the heat exchanger 305 represents an additional thermal load on the circuit 311, in particular with the branch 323 open to the passage of part of the refrigerant. This causes the refrigerant pressure upstream of compressor 313 to increase. As is normally the case for all air conditioning circuits that implement a refrigeration cycle, the flow rate (or speed) of compressor 313 is regulated by the ECU in a closed loop as a function of the pressure difference between the actual refrigerant pressure upstream of compressor 313 (for example, determined by information extracted from the signal measured by transducer 330) and a target inlet pressure, for example a constant. For example, the flow rate can be regulated proportionally (in particular according to a proportional-integrative, proportional-derivative, or proportional-integrative-derivative control law) to the pressure difference. Therefore, due to the heating of the refrigerant upstream of compressor 313, the flow rate of compressor 313 increases, so that compressor 313 moves away from the pumping state (transition from point 1 to point 2 in Figure 11, schematically represented by an arrow). When the phase change material completes its solidification, the material itself stops transferring heat to the refrigerant, so the compressor 313 returns to the near-pumping condition (transition from point 2 to point 3 in figure 11, schematically represented by an arrow). Preferably, the ECU control unit is configured to determine the completion of solidification of the phase change material during the first inspection. This can occur in many ways, for example by extracting information from a signal indicative of a temperature of the phase change material, for example measured by a dedicated temperature sensor of the apparatus 300, or indirectly from the information extracted on the operating variables of the compressor 313, i.e. when the ECU control unit determines an approach on the map of the operating conditions of the compressor 313 towards the pumping state or the condition close to pumping. In fact, the ECU control unit may for example determine a decrease in flow rate, an increase in compression ratio, and / or an increase in coolant temperature during or after the first check, which is indicative of the completion of solidification of the phase change material. The ECU control unit conveniently performs an additional check of the valve device 322 to prevent the passage of coolant through the branch 321, i.e., through the heat exchanger 305, during the first check, so that the coolant does not heat the phase change material and prevent it from solidifying. Upon determination of the completion of solidification or in response thereto, the ECU further controls valve device 325 to prevent the passage of coolant through branch 323, and further controls valve device 322 to allow the passage of coolant through branch 321, i.e., through heat exchanger 305. In particular, the ECU control unit controls the valve device 322 so that the coolant is distributed between the evaporator 310 and the exchanger 305, i.e. between the branches 320, 321. In this way, the portion of coolant passing through the exchanger 305 transfers heat to the phase change material, causing it to liquefy. Thus, the first check can be repeated when the 313 compressor reaches the near-pumping condition or the pumping state. At the same time, the coolant receives extra cooling due to the liquefaction of the phase change material, which results in a benefit to the cooling or air conditioning of the environment (in particular the passenger compartment of the motor vehicle 1) via the radiator 303, even though the compressor 313 approaches the pumping state, thus resulting in less cooling of the coolant via the evaporator 310. The advantage over the prior art is notable. Indeed, Figure 12 shows an example of the temporal trend of the temperature of the environment cooled by the radiator 303 in the implementation of a strategy whereby the compressor 313 is turned off and on at regular intervals when operating in the near-pumping condition. As can be seen from Figure 12, the environment temperature essentially has a sawtooth profile, i.e., with sudden variations that represent a drawback. Instead, with the cyclical application of the first control, as visible in figure 13, the ambient temperature has less abrupt variations, thanks to the action of the heat exchanger 305 on the coolant. From the foregoing, the advantages of the motor vehicle 1 according to the invention are evident. Each of the apparatuses 100, 200, 300, includes a heat exchanger with a phase change material that essentially acts as a latent heat reservoir, which can be exploited through the phase change to manage peak thermal loads or to provide extra cooling to the coolant when the refrigeration cycle operates in suboptimal conditions, for example in low load conditions. Finally, it is clear that modifications and variations can be made to the motor vehicle 1 according to the invention which, however, do not go beyond the scope of protection defined by the claims. In particular, each of the devices schematically depicted in the figures is independent of the other details. Furthermore, the embodiments described and illustrated can be combined with each other arbitrarily to form further embodiments. - 27 Finally, the terms coolant and refrigerant have been used in the description for clarity purposes to distinguish between air conditioning fluids or refrigerant fluids, but it is clear that the coolant can always be replaced by a more generic refrigerant or air conditioning fluid. Similarly, the term radiator can be more generically replaced throughout the description by a generic heat exchanger. Similarly, the term refrigerant can be replaced by the term air conditioning fluid throughout the description. Thus, expressions such as raffreddamento, raffreddamento, and the like can be replaced by more generic expressions such as condizionare, condizionamento, and the like. In the specific examples described, the coolant preferably does not change phase, that is, it always remains liquid, in the circuit in which it circulates.

Claims

1.- Motor vehicle (1) comprising a first air conditioning circuit (101, 201, 311) configured to cyclically circulate a first air conditioning fluid along a first closed loop path (102, 202, 312), the first air conditioning circuit (101, 201, 311) comprising on the first path (102, 202, 312) - a first heat exchanger (103, 210, 310) configured to expose the first air conditioning fluid to a first heat exchange with a second air conditioning fluid external to the first air conditioning circuit (101, 201, 311), and - a second heat exchanger (105, 205, 305) arranged for example downstream or in parallel with respect to the first heat exchanger or in an integrated manner with respect to the first heat exchanger, and comprising a material confined in a closed thermodynamic system, arranged to come into thermal contact with the first air conditioning fluid,and adapted to switch between a solid phase and a liquid phase only when a temperature of the first conditioning fluid in thermal contact with the material satisfies a relationship with a phase change threshold, thus resulting in a second heat exchange between the material and the first conditioning fluid based on a latent heat of the material. 2 .- The motor vehicle according to claim 1, comprising one or more devices (U) configured to generate heat during their operation and arranged to come into thermal contact with the first air conditioning fluid at respective points of the first air conditioning circuit (101) downstream of the second heat exchanger (105) and upstream of the first heat exchanger (103), the second heat exchanger (105) being in turn arranged downstream of the first heat exchanger (103). 3 .- The motor vehicle according to claim 2, wherein the first heat exchanger (103) is defined by a radiator for conditioning the first conditioning fluid via the first heat exchange, wherein the second conditioning fluid is preferably defined by an air flow coming from outside the motor vehicle (1). 4 .- The motor vehicle according to any of claims 1 to 3, wherein the first air conditioning circuit (101) comprises a main branch (106) arranged in parallel to a heat exchange branch (107) comprising the second heat exchanger (105), the first air conditioning circuit (101) further comprising a valve device (108) controllable to selectively admit and prevent a passage of the first air conditioning fluid through the heat exchange branch (107). 5 .- The motor vehicle according to claim 1, further comprising a second air conditioning circuit (211) configured to cyclically circulate the second air conditioning fluid along a second closed loop path (212) passing through the first heat exchanger (210) and configured to create a refrigeration cycle, the second air conditioning circuit (211) comprising along the second path (212) - a compressor (213) configured to compress the second air conditioning fluid, - a condenser (214) configured to condense the second air conditioning fluid compressed by the compressor (213) via a third heat exchange with a further fluid, - at least one lamination valve (215) configured to generate a pressure drop on the second air conditioning fluid condensed by the condenser (214), thus causing it to cool,and - an evaporator defined by the first heat exchanger (210) and configured to evaporate the second conditioning fluid passed through the throttling valve (215) via the first heat exchanger, thereby removing heat from the first conditioning fluid., 6 .- The motor vehicle according to claim 5, comprising one or more devices (U) configured to generate heat during their operation and arranged to come into thermal contact with the first conditioning fluid at respective points of the first conditioning circuit (201) downstream of the second heat exchanger (205) and upstream of a radiator (203) to condition an environment of the motor vehicle (1) after passing through said points. 7 .- The motor vehicle according to claim 1, wherein the first air conditioning circuit (311) is configured to perform a refrigeration cycle, whereby it comprises on the first path (312) - a compressor (313) configured to compress the first air conditioning fluid, - a condenser (314) configured to condense the first air conditioning fluid compressed by the compressor (313) via a third heat exchange with a further fluid, - at least one lamination valve (315) configured to generate a pressure drop on the first air conditioning fluid condensed by the condenser (314), thus causing it to cool, and - an evaporator defined by the first heat exchanger (310) and configured to evaporate the first air conditioning fluid passed through the lamination valve (315) via the first heat exchange, thus removing heat from the second air conditioning fluid,wherein the first conditioning circuit (311) comprises a first and a second branch (323, 324) arranged in parallel to each other along the first path (312) and respectively comprising the second heat exchanger (305) and the group defined by the evaporator and the throttling valve (315), whereby the first conditioning circuit further comprises a first valve device (325) controllable to selectively admit and prevent a passage of the first conditioning fluid through the first branch (323)., 8 .- The motor vehicle according to claim 7, further comprising a control unit (ECU) configured to - determine an onset of a pumping state or a condition close to pumping of the compressor (313), and - perform a first control of the first valve device (325) to admit the passage of the first conditioning fluid through the first branch (323) when the onset of the pumping state or said condition is determined. 9 .- The motor vehicle according to claim 7 or 8, further comprising a second air conditioning circuit (301) configured to cyclically circulate the second air conditioning fluid along a second closed loop path (302) passing through the first heat exchanger (310), the second air conditioning circuit comprising - a radiator (303) downstream of the first heat exchanger (310) to condition a room of the motor vehicle (1) after passing through the first heat exchanger (310), - a third and a fourth branch (320, 321) arranged in parallel to each other and respectively passing through the first and the second heat exchanger (310, 305), so that the second air conditioning fluid can exchange heat respectively with the first air conditioning fluid and the said material,and - a second valve device (322) controllable to selectively admit and prevent a passage of the second conditioning fluid through the fourth branch (321)., 10.- The motor vehicle according to claim 9, when dependent on claim 8, wherein the control unit (ECU) is further configured to - perform a fourth control of the second valve device (322) to prevent the passage of the second conditioning fluid through the fourth branch (321) during the first control, - determine the completion of a solidification of said material during the first control, and 5 - perform a second control of the first valve device (325) to prevent the passage of the first conditioning fluid through the first branch (323) after the solidification is determined, and 5 - perform a third control of the second valve device (322) to admit the passage of the second conditioning fluid through the fourth branch (321) after the solidification is determined.