Patent Application
20240140173
This patent application claims priority from Italian patent application no. 102022000022353 filed on 31 Oct. 2022, the entire disclosure of which is incorporated herein by reference.
The invention concerns a motor vehicle having a conditioning apparatus for cooling electrical devices in the motor vehicle, such as, for example, a battery pack, an electric motor, one or more electrical power converters, and the like.
A motor vehicle normally includes one or more electrical devices.
In particular, an electric motor vehicle, i.e., one having at least one electric motor, typically needs electrical devices that absorb or distribute a significant, or at least not a negligible, quantity of electricity, thus releasing heat during operation.
The heat corresponds to an increase in temperature of the electrical devices, which include the battery pack, the electric motor, and any electrical power converters.
The increase in temperature, if not controlled, may cause the devices to overheat. This, in turn, can entail these devices to malfunction or even be damaged.
In addition, the increase in temperature entails a disadvantage connected to a resulting increase in the electrical resistance of the devices, in turn corresponding to an additional increase in temperature and heat released.
Therefore, the heat issued is usually dissipated using a special conditioning apparatus including a cooling assembly, an additional heat exchanger, and a hydraulic circuit in thermal contact with the electrical devices that release the heat.
The cooling assembly supplies the additional heat exchanger with an evaporating fluid to withdraw heat from the liquid circulating in the hydraulic circuit.
The liquid thus cooled in the heat exchanger continues to circulate along the hydraulic circuit, reaching respective areas of heat exchange with the electrical devices, where the liquid absorbs the heat released by the electrical devices, thus lowering their temperature.
In general, there is a need to improve the known conditioning apparatuses to cool the electrical devices more, thus reducing their electrical resistance and, as a result, establishing a positive cycle wherein the quantity of heat to be dissipated decreases, like the energy expense and space necessary for effective operation of the conditioning apparatuses.
More specifically, there is, in fact, a need to reduce the weight, dimensions, as well as the cost of the known conditioning apparatuses.
One purpose of this invention is to satisfy at least one of the needs described above, preferably in a simple and reliable way.
The purpose is achieved with a motor vehicle as defined in claim 1.
The dependent claims define particular embodiments of the invention.
Below, one embodiment of the invention will be described to better understand the same by way of non-limiting example and with reference to the attached drawings, wherein:
In
In reality,
The conditioning apparatus 2 is suitable for cooling the electrical device 3.
Without any loss of generality, the electrical device 3 could be, for example
The conditioning apparatus 2 comprises at least one refrigerant fluid circuit 4 configured to circulate a refrigerant fluid along a path P.
The circuit 4 is preferably a closed-loop circuit, so that the path P is a closed or closed-loop path. In other words, the refrigerant fluid circulates through the circuit 4 along the path P, preferably cyclically, i.e., repeating the path P several times, more precisely without ever leaving the circuit 4, at least ideally, i.e., without micro losses in the circuit 4 or other issues associated with circuit 4 maintenance or malfunctions, or even without resupplying or choosing to replace the refrigerant fluid.
During a cycle of the refrigerant fluid in the circuit 4 along the path P, the conditioning apparatus 2 implements a refrigeration cycle, in particular a Kelvin or compression refrigeration cycle.
Along the path P, the circuit 4 comprises
In addition, the circuit 4 preferably comprises a drier filter 10, for example a known one, arranged between the condenser 6 and the valve 7, i.e., downstream the condenser 6 or upstream of the valve 7.
The electrical device 3 is arranged in direct thermal contact with the circuit 4 at the zone 8. This means that, at the zone 8, the refrigerant fluid exchanges heat with the electrical device 3 directly through the circuit 4, for example through its tubes, i.e., without exchanging heat with an intermediate fluid, for example water, circulating through an additional circuit separate from the circuit 4, in particular an additional closed circuit.
The exchange of heat between the refrigerant fluid at the zone 8 with the electrical device 3 through the circuit 4 can be via conduction, for example by direct contact between the circuit 4 and the electrical device 3, or via convection.
For clarity, the meaning of direct thermal contact includes a thermal contact wherein the heat passes from the electrical device 3 to the refrigerant fluid at the zone 8 through a layer of air between the circuit 4 and the electrical device 3, more specifically air that is not forced through a specific circuit, but stagnant or randomly moving there.
The heat exchange zone 8 is conceptually part of an evaporator 9 of the circuit 4. The evaporator 9 is arranged downstream the valve 7 and is configured to evaporate the refrigerant fluid that passed through the valve 7 via heat exchange with the electrical device 3 at the zone 8.
Thus, during operation of the conditioning apparatus 2, the refrigerant fluid is compressed by the compressor 5. In this first step, the refrigerant fluid is compressed and heated in an aeriform state or, more precisely, in an over-heated vapour state.
At this point, the second step, the refrigerant fluid crosses the condenser 6, undergoing a state transition from the aeriform state to the liquid state there.
In a third step, at least part of the refrigerant fluid passes through the valve 7; the pressure drop caused by the valve 7 causes the cooling of the refrigerant fluid and, potentially, an initial partial evaporation, so that the refrigerant fluid could be in a semi-liquid state, i.e., could contain a liquid part and an aeriform part.
In a fourth step, the refrigerant fluid, which has passed through the valve 7, evaporates at the zone 8 absorbing heat from the electrical device 3 and, thus, cooling the latter.
Thus, the evaporator 9 contributes at least to causing a state transition of the refrigerant fluid to the aeriform state.
Having absorbed heat from the electrical device 3 and, thus, being heated, the refrigerant fluid returns to the compressor 5 to repeat the steps described above.
A significant aspect of the above is that the refrigerant fluid undertakes or is in a phase or physical state transition from the liquid state to the aeriform state when it exchanges heat with the electrical device 3.
Therefore, the refrigerant fluid is suitable for evaporating when or while it is in thermal contact with the electrical device 3, i.e., with a device having a given temperature typical of its operation.
Advantageously, the electrical device 3 is entirely arranged within the circuit 4 at the zone 8. Therefore, the refrigerant fluid at the zone 8 enters directly into contact with the electrical device 3 or laps the latter along the circuit 4 or the path P.
According to a more specific example, when the electrical device 3 is a battery pack, i.e., it comprises multiple batteries, the refrigerant fluid at the zone 8 passes into the spaces or gaps between the batteries. In other words, the circuit 4 comprises channels for the passage of the refrigerant fluid between said spaces between the batteries.
Alternatively, or more specifically, the electrical device 3 comprises at least one conducting element for conducting electrical current, for example an electrical winding, a printed circuit, a power electronics component, and the like. The conducting element is arranged within the circuit 4 at the zone 8. Therefore, the refrigerant fluid at the zone 8 enters directly into contact with the conducting element or directly laps the conducting element along the circuit 4 or the path P.
An example of a conducting element for an electric motor may be a stator winding or a rotor winding.
An example of a conducting element for an inverter or, more generally, for a converter may be a power electronics circuit.
In other words, the conducting element is an element through which, in use, the electrical current effectively passes.
Thus, the electrical device 3 having the conducting element is configured to operate via an effective passage or a conduction of electrical current through the conducting element.
In other words, the electrical device 3 is configured so that an electrical current passes through the conducting element during the operation thereof (ergo, during the operation of the electrical device 3).
Again, in other words, the conducting element is configured to conduct the electrical current during the operation of the electrical device 3.
According to the embodiment in
The second circuit 11 is similar to the first circuit 4, so it will only be described in what distinguishes it from the first circuit 4. In particular, the evaporator 9 is replaced by another evaporator 12 configured to evaporate the refrigerant fluid via heat exchange with air inside the motor vehicle 1 passenger compartment.
In this way, the evaporator 12 or the circuit 11 conditions the passenger compartment.
In practice, the circuit 11 defines an air conditioning device configured to condition the motor vehicle 1 passenger compartment.
The circuits 11 and the circuit 4 are independent of each other. Therefore, the respective refrigerant fluids circulating along the circuits 4, 11 could be different.
The circuit 11 is not essential, so it may also be absent.
According to the embodiment in
Preferably, but not necessarily, the circuit 4 in
In particular, the evaporator 12 is immediately or directly downstream the valve 13.
The valve 13 has the same function as the valve 7, i.e., it is configured to cause a pressure drop on part of the refrigerant fluid.
More precisely, the valves 7, 13 are arranged in parallel like the evaporators 9, 12, so that the valves 7, 13 are configured to produce corresponding pressure drops on two separate portions of the refrigerant fluid condensed by the condenser 6.
In other words, the refrigerant fluid coming from the condenser 6 is divided between the valves 7, 13 respectively, before reaching the zone 8 and the evaporator 12.
According to the variant in
The electrical device 14 is arranged in direct thermal contact with the circuit 4 in another heat exchange zone 15 arranged in parallel with the first heat exchange zone 8.
The situation of the heat exchange zones 8, 15 is similar, so that the circuit 4 comprises, in addition, an evaporator 16 arranged in parallel with the evaporator 9 and configured to evaporate the refrigerant fluid passing through the evaporator 16 via heat exchange with the electrical device 14 in the heat exchange zone 15, thus contributing to causing the state transition of the refrigerant fluid to the aeriform state.
Preferably, but not necessarily, the circuit 4 also comprises an additional expansion valve device 17 upstream of the evaporator 16 and downstream the condenser 6, i.e., between the condenser 6 and the evaporator 16.
In particular, the evaporator 16 is immediately or directly downstream the valve 17.
The valve 17 has the same function as the valve 7, i.e., it is configured to cause a pressure drop on part of the refrigerant fluid.
More precisely, the valves 7, 17 are arranged in parallel like the evaporators 9, 16, so that the valves 7, 17 are configured to produce corresponding pressure drops on two separate portions of the refrigerant fluid condensed by the condenser 6.
In other words, the refrigerant fluid coming from the condenser 6 is divided between the valves 7, 17 respectively, before reaching the zones 8, 15.
The presence of the evaporator 12 and the corresponding valve 13 is not necessary; in fact, in the variant in
In the variant in
In practice, the refrigerant fluid always evaporates more through the two evaporators 9, 20 in series, passing to the gaseous state. In the meantime, the refrigerant fluid sequentially cools the two electrical devices 3, 18.
The variant in
The variant in
Similarly, the variant in
Again, similarly, the variant in
In addition, the variant in
The refrigerant fluid preferably comprises an alkyl halide, for example a chlorofluorocarbon, in particular freon.
In addition, independently, the refrigerant fluid at room temperature has a resistivity greater than 1.106 Ωm. “Room temperature” means a temperature between 15° and 30°, in particular 20°.
In addition, the refrigerant fluid at room temperature or, more precisely, at approximately 21°, has a liquid dielectric constant greater than 7.7.
The upper flammability limit of the refrigerant fluid is preferably less than 13% by volume in air. In addition, independently, the lower flammability limit of the refrigerant fluid is greater than 5% by volume in air.
In addition, the spontaneous ignition temperature of the refrigerant fluid is greater than 400°.
The invention also relates to a process for cooling any one or any set of electrical devices 3, 14, 18, 22.
The process comprises
The refrigerant fluid preferably directly laps the electrical device with which it exchanges heat or laps one of its electrical energy conducting elements during evaporation.
In addition, the process may preferably comprise additional cooling of a portion of the condensed refrigerant fluid via the valve 13 and additional evaporation of the latter portion via heat exchange with the air inside the passenger compartment of the motor vehicle 1.
Conveniently, the process may comprise cooling in series of one of the devices 3, 14 and of the next one between the devices 18, 22 during evaporation via respective sequential heat exchanges between the refrigerant fluid and the corresponding heat exchange devices.
In addition, the process may comprise additional cooling in parallel of a portion of the condensed refrigerant fluid via the other valves 7, 17 and additional evaporation of the portion of the refrigerant fluid via direct heat exchange with the other of the devices 3, 14.
More generally, any aspect of the operation of the conditioning apparatus 2 may be part of the process according to the invention.
From the above, the advantages of the motor vehicle 1 and the process according to the invention are clear.
First of all, the circuits 4, 11 do not require maintenance except for specific breakdowns.
In addition, the direct use of the refrigerant fluid to cool the electrical devices 3, 14, 18, 22 during evaporation makes it possible to avoid the use of additional heat exchange fluids with consequent savings in weight, dimensions, and costs.
In addition, the refrigerant fluid has poor thermal conductivity, so it can effectively enter into direct contact with the conducting elements of the electrical devices 3, 14, 18, 22.
Again, cooling occurs much more effectively than in the prior art, with the consequent establishment of a positive recursive effect so that the electrical devices 3, 14, 18, 22 generate less and less heat thanks to the lower and lower temperatures, thus reducing, more and more, the quantity of refrigerant fluid needed for the conditioning.
Finally, it is clear that changes may be made to the overheating device according to the invention, and variations produced thereof, that, in any case, do not depart from the scope of protection defined by the claims.
In particular, each of the devices schematically represented in the figures is independent of the other details and is, specifically, devised to resolve specific technical problems in isolation to the other details.
| Number | Date | Country | Kind |
|---|---|---|---|
| 102022000022353 | Oct 2022 | IT | national |
