Heat treatment method for a heat treatment system

Abstract

The present invention relates to a heat treatment method for a heat treatment system (1) comprising a coolant circuit (3) and a heat transfer fluid circuit (2), the coolant circuit (3) comprising a main path (4), a first path (9) and a second path (10), the first path (9) comprising a first expansion member (11) and a second heat exchanger (12), the second path (10) comprising a third heat exchanger (14), the heat transfer fluid circuit (2) comprising a first sub-circuit (16) provided with the first heat exchanger (6) and the second heat exchanger (12), and a second sub-circuit (17) comprising the third heat exchanger (14), characterised in that the heat treatment method comprises a step during which the pressure within the second heat exchanger (12) is increased.

Description

[0001] DESCRIPTION

[0002] Title of the invention: Heat treatment method for a heat treatment system

[0003] The present invention relates to the field of heat treatment systems of a motor vehicle, and more particularly concerns a heat treatment process applied within such heat treatment systems.

[0004] Motor vehicles are commonly equipped with a refrigerant circuit and at least one heat transfer fluid circuit, both used to contribute to the thermal treatment of different areas or components of the vehicle. It is particularly well known that the refrigerant and / or heat transfer fluid circuits are used to thermally treat an airflow directed into the passenger compartment of vehicles equipped with such a system. This thermal treatment is achieved primarily through the circulation of the refrigerant within a ventilation, heating, and / or air conditioning system installed in the vehicle.

[0005] In another application of this circuit, the heat transfer fluid circuit is known to be used to cool components of the vehicle's powertrain, such as an electrical storage device. This device is used to supply energy to an electric motor that propels the vehicle. The heat treatment system thus provides the energy needed to cool the electrical storage device during operation while driving.

[0006] To implement these different configurations, two heat exchangers are dedicated to cooling the heat transfer fluid through heat exchange within the refrigerant circuit. These two heat exchangers are located on a specific line of the refrigerant circuit, and these two lines are connected in parallel.

[0007] It sometimes happens that a pressure differential forms between these two paths and that an unwanted return of refrigerant occurs within an unused path once the refrigerant has circulated within the used path. The present invention falls within this context and, as such, proposes a method for the heat treatment of a vehicle's heat treatment system, the heat treatment system comprising a refrigerant circuit and a heat transfer fluid circuit, the refrigerant circuit comprising a main path extending between a convergence zone and a divergence zone and including a compression device and a first heat exchanger configured to perform heat exchange between a refrigerant circulating in the refrigerant circuit and a heat transfer fluid circulating in the heat transfer fluid circuit.the refrigerant circuit further comprising a first path and a second path both extending between the divergence zone and the convergence zone, the first path comprising a first expansion device and a second heat exchanger configured to operate a heat exchange between the refrigerant circulating in the refrigerant circuit and the heat transfer fluid circulating in the heat transfer fluid circuit, the second path comprising a second expansion device and a third heat exchanger configured to operate a heat exchange between the refrigerant circulating in the refrigerant circuit and the heat transfer fluid circulating in the heat transfer fluid circuit, the heat transfer fluid circuit comprising a first sub-circuit provided with a first pumping device, the first heat exchanger and the second heat exchanger,and a second sub-circuit comprising a second pumping device and the third heat exchanger, characterized in that the heat treatment process comprises a main step in which the pressure is increased within the second heat exchanger while the first expansion valve is closed.

[0008] This process, by increasing the pressure within the unused heat exchanger of the refrigerant circuit, reduces the pressure differential between the first and second circuits, thus preventing refrigerant from flowing back into the first circuit. This is achieved without the need for a dedicated fluid control unit. The heat treatment system is equipped with several components that provide multiple heat treatment functions for the vehicle's interior or powertrain. Within the refrigerant circuit, the compression device circulates and compresses the refrigerant to a high pressure and temperature, reducing it to a gaseous state.The refrigerant is condensed using the first heat exchanger through heat exchange with the heat transfer fluid, the latter capturing calories from the refrigerant and thus being heated by circulating within the first heat exchanger.

[0009] The refrigerant can subsequently circulate within the first and / or second channel, depending on the requirements of the heat treatment system. However, the heat treatment process according to the invention is implemented when the refrigerant circulates only within the second channel.

[0010] Both the first and second paths include an expansion valve to reduce the pressure and temperature of the refrigerant. Once at a low temperature, the refrigerant evaporates within the second or third heat exchanger, thus cooling the heat transfer fluid circulating within these exchangers. At the outlet of at least one of the heat exchangers, the evaporated refrigerant returns to the main path and is compressed again by the compression device.

[0011] In the heat transfer fluid circuit, the first sub-circuit is primarily dedicated to heating the vehicle's passenger compartment, while the second sub-circuit is dedicated to heating at least one component of the vehicle's powertrain. Pumping devices circulate the heat transfer fluid, which can be, for example, glycol water. The heat exchangers in the sub-circuits, as described previously, heat or cool the heat transfer fluid and use it to heat or cool the vehicle's passenger compartment or one of the components of the vehicle's powertrain. The pressure in the second heat exchanger increases when it is not in use, i.e., when there is no heat exchange. The second heat exchanger can, for example, increase in pressure due to a rise in temperature.Once this is done, the refrigerant is no longer subject to unwanted fluid return due to a differential pressure potential.

[0012] According to a characteristic of the process, the main step of the process comprises the following substeps:

[0013] - The first expansion valve is closed and refrigerant is circulated through the refrigerant circuit.

[0014] - Heat transfer fluid is circulated within the second sub-circuit,

[0015] - heat transfer fluid is circulated within the first sub-circuit, the heat transfer fluid circulating at least within the first heat exchanger and the second heat exchanger.

[0016] One solution to increase the pressure of the second heat exchanger is therefore to circulate hot heat transfer fluid through it without heat exchange, in order to increase its temperature, thus causing a rise in pressure.

[0017] The first expansion valve is closed to prevent refrigerant from circulating in the first channel. It is therefore understood that this method is used exclusively to subsequently implement a circulation mode for the heat treatment system that does not utilize the first channel of the refrigerant circuit. The refrigerant thus circulates only within the main channel and the second channel.

[0018] The heat transfer fluid circulates within the first and second sub-circuits of the heat transfer fluid circuit. Circulation within the second sub-circuit is implemented to cool the heat transfer fluid using the refrigerant in the third heat exchanger. This cooled heat transfer fluid then cools a component of the vehicle's powertrain. The heat transfer fluid circulating in the first sub-circuit must first pass through the first heat exchanger to be heated by the refrigerant, and then circulate hot through the second heat exchanger to increase its temperature, and therefore its pressure. This significantly reduces the pressure differential between the first and second circuits, preventing refrigerant from flowing back into the first circuit after exiting the second.

[0019] According to a characteristic of the process, the main step is carried out for a period of between 30 and 120 seconds. The circulation of hot heat transfer fluid in the second heat exchanger allows for a rapid increase in pressure, thus ensuring a quick execution of the process before it can be interrupted to implement only the circulation modes intended to thermally treat the passenger compartment and / or the components of the vehicle's powertrain.

[0020] According to a characteristic of the process, it is implemented by the heat treatment system in which the first sub-circuit includes a divergence point disposed on the first sub-circuit between the first heat exchanger and the second heat exchanger and a fourth heat exchanger configured to operate a heat exchange between the heat transfer fluid and an interior airflow intended to be sent into the vehicle's passenger compartment, during which the heat transfer fluid circulates within the first heat exchanger and then divides into a first fraction circulating within the second heat exchanger and a second fraction circulating within the fourth heat exchanger, the first fraction and the second fraction dividing at the divergence point.

[0021] The fourth heat exchanger contributes to heating the vehicle's passenger compartment. Once the heat transfer fluid is heated in the first heat exchanger, the fourth heat exchanger heats the incoming airflow through the first exchanger. This heat transfer fluid then transfers its heat to the incoming air. The heated airflow is then circulated into the vehicle's passenger compartment for heating and cooling. The fourth heat exchanger can be integrated into the ventilation, heating, and / or air conditioning system.

[0022] As part of the heat treatment process, a portion of the heated heat transfer fluid can be used to heat the vehicle's passenger compartment if necessary. The divergence point allows the heat transfer fluid exiting the first heat exchanger to be separated into two fractions. The first fraction can then circulate within the second heat exchanger to carry out the heat treatment process as described previously, while the second fraction contributes to heating the vehicle's passenger compartment by circulating within the fourth heat exchanger.

[0023] The first sub-circuit is configured so that the heat transfer fluid fractions can join upstream of the first heat exchanger at the outlet of the second heat exchanger or the fourth heat exchanger.

[0024] According to one characteristic of the process, it is implemented by the heat treatment system in which the first sub-circuit includes a fifth heat exchanger configured to perform heat exchange between the heat transfer fluid and an outside airflow. The heat treatment system includes a shut-off device configured to switch between at least an open position and a closed position to respectively permit or prevent the passage of the outside airflow through the fifth heat exchanger. The heat treatment process includes a sub-step in which the shut-off device is closed. The first sub-circuit provides passive heat treatment of the heat transfer fluid via the fifth heat exchanger and the outside airflow passing through it.The fifth heat exchanger is thus useful for dissipating heat sufficiently without requiring additional energy input.

[0025] External airflow refers to airflow that is not intended to be directed into the vehicle's passenger compartment. To align with the external airflow path, the fifth heat exchanger can, for example, be positioned on the front of the vehicle.

[0026] The shutter device allows or prevents the flow of outside air. Intermediate positions for the shutter device also exist, depending on the volume of outside air needed to dissipate the heat from the heat transfer fluid. Closing the shutter device helps reduce vehicle fuel consumption by improving its aerodynamics.

[0027] In the heat treatment process, the heat transfer fluid must be as hot as possible to increase the pressure in the second heat exchanger as quickly as possible. Since the fifth heat exchanger is located between the first and second heat exchangers, the shut-off device is advantageously in the closed position to prevent heat loss from the heat transfer fluid circulating within the second heat exchanger.

[0028] According to one characteristic of the process, it is implemented by the heat treatment system in which the first sub-circuit includes a cooling branch fluidically connected to the second heat exchanger. The cooling branch includes a sixth heat exchanger configured to perform heat exchange between the heat transfer fluid and the indoor airflow. The cooling branch is used for a configuration of the heat treatment system that does not involve the heat treatment process. The cooling branch connects the second heat exchanger to the sixth heat exchanger in order to initially cool the heat transfer fluid within the second heat exchanger.

[0029] The cooled heat transfer fluid then circulates to the sixth heat exchanger, thus cooling the incoming airflow before it is sent into the vehicle's passenger compartment. The air conditioning system therefore contributes to cooling the vehicle's passenger compartment. As such, the sixth heat exchanger can be integrated into the ventilation, heating, and / or air conditioning system mentioned earlier.

[0030] According to a characteristic of the process, it is implemented by a heat treatment system in which the second sub-circuit includes a seventh heat exchanger configured to thermally treat a vehicle's electrical storage device. The seventh heat exchanger is advantageously positioned downstream of the third heat exchanger within the second sub-circuit, according to the direction of flow of the heat transfer fluid. As mentioned previously, the third heat exchanger allows the refrigerant to evaporate while simultaneously cooling the heat transfer fluid. The cooled heat transfer fluid then flows into the seventh heat exchanger to cool the electrical storage device.

[0031] According to a characteristic of the process, it is implemented by the heat treatment system in which the second sub-circuit includes a bypass branch extending parallel to the seventh heat exchanger. The bypass branch allows the heat transfer fluid to circulate in the second sub-circuit without passing through the seventh heat exchanger. Thus, when there is no need to heat the electrical storage device, but the heat transfer fluid is, for example, cooled via the third heat exchanger for a heat treatment purpose other than that of the electrical storage device, the bypass branch prevents the heat transfer fluid from passing through the seventh heat exchanger and disturbing its temperature.

[0032] According to one characteristic of the process, it is implemented by the heat treatment system in which the heat transfer fluid circuit includes a cooling branch equipped with an eighth heat exchanger configured to heat a vehicle's electric motor. This cooling branch is fluidically connected to the first sub-circuit. The heat transfer fluid circuit can thus provide heat treatment, via the eighth heat exchanger, which can, for example, cool the electric motor through the cooling branch. Such an operation may be necessary if the electric motor temperature becomes too high. For example, the electric motor can reach a high temperature when driving at high speeds, such as on the highway.

[0033] According to a characteristic of the process, it is implemented by the heat treatment system in which the heat transfer fluid circuit comprises a first connecting branch and a second connecting branch that fluidly links the cooling branch to the second sub-circuit. This first connecting branch ensures a fluid connection, notably between the eighth and third heat exchangers, enabling motor cooling, and also between the eighth and seventh heat exchangers to allow indirect heat exchange between the electric motor and the electrical storage device. The second connecting branch completes the fluid connection between the cooling branch and the second sub-circuit in a closed manner. The second connecting branch is therefore essential for performing the functions mentioned above.

[0034] According to a characteristic of the process, it is implemented by the heat treatment system in which the second sub-circuit includes an electric heating element for the heat transfer fluid. The electric heating element heats the heat transfer fluid using an external energy input. Depending on the requirement, the electric heating element is therefore capable of heating the heat transfer fluid circulating in the second sub-circuit.

[0035] According to one feature of the process, it is implemented by a heat treatment system in which the refrigerant circuit lacks a fluid control device on the first line between the second heat exchanger and the convergence zone. As described previously, the heat treatment process according to the invention eliminates the need for this fluid control device because the pressure differential responsible for a potential return flow of refrigerant in the first line is significantly reduced. Any risk of fluid return is thus eliminated. The aforementioned fluid control device could, for example, be a valve or a check valve.

[0036] Other features and advantages of the invention will become apparent from the following description on the one hand, and from several illustrative and non-limiting examples of embodiments given with reference to the attached schematic drawings on the other hand, in which:

[0037] [fig 1] represents a heat treatment system comprising a refrigerant circuit and a heat transfer fluid circuit,

[0038] [fig 2] illustrates a mode of circulation of the fluid(s) circulating in the heat treatment system during a heat treatment process according to the invention.

[0039] The terms upstream and downstream used in the following description refer to the direction of flow of the fluid in question, i.e. the refrigerant or the heat transfer fluid.

[0040] In Figure 1, a heat transfer fluid circuit 2 is shown with solid lines and a refrigerant circuit 3 is shown with dashed lines. In Figure 2, the portions through which their respective fluids flow are shown with solid lines, and the portions without fluid circulation are shown with short dashed lines. The solid lines indicating fluid circulation also vary in thickness for the refrigerant circuit 3 when it is in use. More specifically, the thickest solid lines correspond to portions where the refrigerant flows at high pressure, and the thinnest solid lines correspond to portions where the refrigerant flows at low pressure.

[0041] Figure 1 represents a heat treatment system 1 that can be integrated into a motor vehicle and comprises a heat transfer fluid circuit 2 and a coolant circuit 3. This heat treatment system 1 is capable of providing heat treatment for the vehicle's passenger compartment, as well as for various components of the vehicle's powertrain. The heat treatment system 1 is configured to operate different interactions between the heat transfer fluid and the coolant in order to optimally heat the vehicle's passenger compartment and the various components of the vehicle's powertrain.The heat transfer fluid can, for example, be glycol water, while the refrigerant can advantageously be an R290 type fluid, i.e. propane, which meets European environmental protection standards unlike other types of refrigerant used for heat treatment.

[0042] The refrigerant circuit 3 comprises a main channel 4 equipped with a compression device 5 that circulates the refrigerant within the circuit, and a first heat exchanger 6 configured to perform heat exchange between the refrigerant and the heat transfer fluid circulating in the heat transfer fluid circuit 2. The first heat exchanger 6 heats the heat transfer fluid while simultaneously condensing the refrigerant. The main channel 4 extends between a convergence zone 7 and a divergence zone 8.

[0043] The refrigerant fluid circuit 3 also includes a first path 9 and a second path 10 extending between the divergence zone 8 and the convergence zone 7 and arranged in parallel with each other.

[0044] The first channel 9 includes a first expansion device 11 and a second heat exchanger 12. The second heat exchanger 12 is configured to perform a heat exchange between the heat transfer fluid circulating in the heat transfer fluid circuit 2 and the refrigerant circulating in the refrigerant fluid circuit 3. The second heat exchanger 12 allows the heat transfer fluid to be cooled and the refrigerant to be evaporated.

[0045] The second path 10 includes a second expansion member 13 and a third heat exchanger 14. Just like the second heat exchanger 12, the third heat exchanger 14 is configured to perform a heat exchange between the heat transfer fluid circulating in the heat transfer fluid circuit 2 and the refrigerant circulating in the refrigerant fluid circuit 3. The third heat exchanger 14 allows the heat transfer fluid to be cooled and the refrigerant to be evaporated.

[0046] Each of the expansion valves 11, 13 ensures the expansion of the refrigerant, which then decreases in pressure and temperature. Subsequently, the refrigerant can pass through the second heat exchanger 12 or the third heat exchanger 14, depending on the flow path. This choice of path is obviously dependent on the objectives that the heat treatment system 1 must fulfill.

[0047] Subsequently, the first channel 9 and the second channel 10 rejoin to reform the main channel 4. Since the compression device 5 is only capable of compressing refrigerant in a gaseous state, the refrigerant circuit 3 may advantageously include an accumulation device 15 located on the main channel 4 upstream of the compression device 5. This device retains a liquid fraction of the refrigerant before it passes through the compression device 5 and damages it. The refrigerant circuit 3 may also include an internal heat exchanger, not shown in the figures, for regulating the thermodynamic equilibrium of the refrigerant.

[0048] The heat transfer fluid circuit 2 includes in particular a first sub-circuit 16 and a second sub-circuit 17, each of the sub-circuits 16, 17 interacting with at least one of the three heat exchangers described previously.

[0049] The first sub-circuit 16 includes a first pumping device 18 suitable for circulating the heat transfer fluid, and as previously described, the heat transfer fluid absorbs heat from the refrigerant and is thus heated by circulating within the first heat exchanger 6. The heat transfer fluid circulating in the first sub-circuit 16 can also interact with the second heat exchanger 12 in order to be cooled by the refrigerant, which has been previously expanded by the first expansion device 11. The first sub-circuit 16 may optionally include an additional pumping device 19 in order to form two heat transfer fluid loops within the first sub-circuit 16, each being dedicated to a different thermal function and including its own pumping device for circulating the heat transfer fluid.

[0050] The second sub-circuit 17 includes a second pumping device 20 capable of circulating the heat transfer fluid within the second sub-circuit 17 and allows the circulation of the heat transfer fluid within the third heat exchanger 14.

[0051] The first sub-circuit 16 further includes a heating branch 21 equipped with a fourth heat exchanger 22. The heating branch 21 starts at a divergence point 23 located on the first sub-circuit 16 between the first heat exchanger 6 and the second heat exchanger 12.

[0052] The heating branch 21 allows the circulation of at least part of the heat transfer fluid previously heated within the first heat exchanger 6 to the fourth heat exchanger 22.

[0053] The fourth heat exchanger 22 is configured to perform heat exchange between the heat transfer fluid and an interior airflow 24 intended to be sent to the vehicle's passenger compartment for thermal treatment. The fourth heat exchanger 22 is therefore advantageously located within a ventilation, heating, and / or air conditioning system 25. The fourth heat exchanger 22 contributes to heating the vehicle's passenger compartment by absorbing heat from the refrigerant in the first heat exchanger 6 and then transferring it to the interior airflow 24 as it circulates within the fourth heat exchanger 22.

[0054] The first sub-circuit 16 also includes a fifth heat exchanger 26 configured to perform heat exchange between the heat transfer fluid and an outside airflow 27. Outside airflow is defined as airflow not intended to be directed into the vehicle's passenger compartment. To be positioned along the path of the outside airflow 27, the fifth heat exchanger 26 can, for example, be located on the front of the vehicle. The fifth heat exchanger 26 is situated on the first sub-circuit 16 between the divergence point 23 and the second heat exchanger 12.

[0055] The fifth heat exchanger 26 ensures heat dissipation from the heat transfer fluid using the outside airflow 27. Furthermore, the heat treatment system 1 includes a shutter device 28 interposed across the outside airflow 27, upstream of the fifth heat exchanger 26 with respect to the direction of circulation of the outside airflow 27. The shutter device 28 is configured to switch at least between an open position and a closed position to respectively allow or prevent the passage of the outside airflow 27 through the fifth heat exchanger 26.

[0056] The first sub-circuit 16 also includes an air conditioning branch 29 provided with a sixth heat exchanger 30. The air conditioning branch 29 is connected to the rest of the first sub-circuit 16, at least on both sides of the additional pumping device 19 and the second heat exchanger 12 in order to form a heat transfer fluid loop between the second heat exchanger 12 and the sixth heat exchanger 30.

[0057] Just like the fourth heat exchanger 22, the sixth heat exchanger 30 is configured to perform a heat exchange between the heat transfer fluid and the interior airflow 24. The sixth heat exchanger 30 is therefore also advantageously located within the ventilation, heating and / or air conditioning system 25. The sixth heat exchanger 30 thus contributes to the air conditioning of the vehicle's passenger compartment when necessary.

[0058] The second sub-circuit 17 includes a seventh heat exchanger 31 which provides thermal treatment to the vehicle's electrical storage device using the heat transfer fluid. As it circulates through the seventh heat exchanger 31, the heat transfer fluid is able to heat or cool the electrical storage device according to their respective temperatures. The electrical storage device may require thermal treatment, for example, cooling after rapid vehicle charging or heating when the vehicle starts. To provide such thermal treatment, the seventh heat exchanger 31 is advantageously located downstream of the third heat exchanger 14 within the second sub-circuit 17.

[0059] The second sub-circuit 17 also includes an electric heating element 32 arranged upstream of the third heat exchanger 14. The electric heating element 32 can, for example, be used to heat the electrical storage device via the seventh heat exchanger 31 or to participate in the thermodynamic cycle of the refrigerant by heating the heat transfer fluid in order to subsequently facilitate the evaporation of the refrigerant when the heated heat transfer fluid circulates within the third heat exchanger 14.

[0060] The second sub-circuit 17 also includes a bypass branch 33 arranged in parallel with the seventh heat exchanger 31 and allowing it to be bypassed in the event of a configuration using the second sub-circuit 17 but without thermally treating the electrical storage device.

[0061] In addition to the first sub-circuit 16 and the second sub-circuit 17, the heat transfer fluid circuit 2 includes a cooling branch 34 equipped with a fourth pumping device 35 and an eighth heat exchanger 36 configured to thermally treat an electric motor of the vehicle.

[0062] The cooling branch 34 is connected to the first sub-circuit 16 in order to fluidly link the eighth heat exchanger 36 to the fifth heat exchanger 26 and thus perform a passive thermal treatment of the electric motor through the dissipation of heat carried out by the outside airflow 27.

[0063] Furthermore, the heat transfer fluid circuit 2 includes a first connecting branch 37 and a second connecting branch 38 connecting the cooling branch 34 to the second sub-circuit 17. The connecting branches 37, 38 allow the eighth heat exchanger 36 to be fluidly linked to the third heat exchanger 14 in order to operate active cooling of the electric motor, or the eighth heat exchanger 36 to be fluidly linked to the seventh heat exchanger 31 in order to operate heating of the electrical storage device thanks to the heat emitted by the electric motor.

[0064] A plurality of points in the heat transfer fluid circuit 2 can be equipped with a bypass device 39 allowing the heat transfer fluid to be directed to a sub-circuit or branch according to the desired configuration for the heat treatment system 1.

[0065] Figure 2 illustrates a circulation method implementing a heat treatment process according to the invention. It should be noted that the heat treatment system 1 is nevertheless capable of implementing a plurality of other circulation methods providing heating or air conditioning for the vehicle's passenger compartment, as well as heat treatment for the electric motor and / or the electrical storage device.

[0066] More specifically, the circulation method illustrated in Figure 2 is mainly implemented for the purpose of cooling the electrical storage device.

[0067] At the level of the refrigerant circuit 3, when cooling of the electrical storage device is required, the refrigerant circulates in particular within the second line 10. In a configuration where the refrigerant only circulates in the second line 10, it may happen that due to a pressure differential, at least part of the refrigerant circulates in the first line 9 once it has reached the convergence zone 7, instead of continuing its circulation within the main line 4.

[0068] The heat treatment process according to the invention, applied to the heat treatment system 1, prevents such a situation while avoiding the need to put in place a fluidic control device, such as a valve or a check valve, between the second heat exchanger 12 and the convergence zone 7.

[0069] A key step in this heat treatment process according to the invention is to increase the pressure of the second heat exchanger 12 while the first expansion valve 11 is closed. This eliminates the pressure differential between the first port 9 and the second port 10, preventing the refrigerant from flowing back into the first port 9 without requiring the installation of the fluid control device there.

[0070] To increase the pressure within the second heat exchanger 12, several sub-steps are implemented, initiated either simultaneously or sequentially. During one of these sub-steps, the first expansion valve 11 is closed to prevent the circulation of refrigerant within the first channel 9, but the refrigerant circuit remains active. The refrigerant thus circulates within the main channel 4 and the second channel 10.

[0071] More specifically, the refrigerant is circulated using the compression device 5 and then condensed by circulating within the first heat exchanger 6. Upon reaching the divergence zone 8, the refrigerant can only circulate within the second channel 10 because the first expansion valve 11 is closed and prevents any circulation within the first channel 9. The refrigerant is then expanded by the second expansion valve 13 and is evaporated by circulating within the third heat exchanger 14.

[0072] The refrigerant then joins the main path 4 via the convergence zone 7, circulates within the accumulation device 15 which retains a liquid fraction of the refrigerant if the latter has not completely evaporated, and is then compressed again by the compression device 5.

[0073] In parallel with the refrigerant circulation, another sub-step involves circulating heat transfer fluid within the second sub-circuit 17 to cool the electrical storage device. The heat transfer fluid is circulated by the second pumping device 20, passes through the electric heating element 32 (which may or may not be active), and then flows through the third heat exchanger 14 to be cooled by the low-pressure refrigerant. The heat exchange taking place in the third heat exchanger 14 cools the heat transfer fluid while simultaneously evaporating the refrigerant. At the outlet of the third heat exchanger 14, the low-temperature heat transfer fluid then flows through the seventh heat exchanger 31 to absorb the heat emitted by the electrical storage device and thus cool it.

[0074] Finally, simultaneously, in another sub-step, heat transfer fluid circulates within the first sub-circuit 16, passing at least through the first heat exchanger 6 and the second heat exchanger 12. The heat transfer fluid is initially heated by the refrigerant as it circulates through the first heat exchanger 6, thus condensing the refrigerant. The heat transfer fluid then circulates through the second heat exchanger 12 without any heat exchange. The circulation of hot heat transfer fluid within the second heat exchanger 12 then increases its pressure, thus limiting the pressure differential that may exist between the first line 9 and the second line 10 of the refrigerant circuit 3.

[0075] Thus, when, during the heat treatment process, refrigerant circulates within the second channel 10 and participates in heat exchange with the heat transfer fluid also circulating within the second sub-circuit 17 via the third heat exchanger 14, there is no risk that the refrigerant, once it reaches the convergence zone 7 at the outlet of the second channel 10, will flow back into the first channel 9. This process therefore prevents any fluid from flowing back into the first channel 9, without the need for any fluid control device. The main step is preferably carried out over a period of between 30 and 120 seconds.

[0076] As illustrated in Figure 2, the sub-step in which the heat transfer fluid circulates within the first sub-circuit 16 can be implemented so that the heat transfer fluid, upon reaching the divergence point 23, splits into two fractions: a first fraction circulating to the second heat exchanger 12 to increase the pressure within it, as described previously, and a second fraction circulating in the heating branch 21 to circulate within the fourth heat exchanger 22, where it transfers its heat to the interior airflow 24, which is then sent to the vehicle's passenger compartment. This configuration is implemented when it is necessary to carry out the heat treatment process in such a way as to increase the pressure of the second heat exchanger 12 while simultaneously heating the vehicle's passenger compartment.The heat transfer fluid fractions subsequently join upstream of the first heat exchanger 6.

[0077] To circulate from the first heat exchanger 6 to the second heat exchanger 12, the heat transfer fluid must circulate within the fifth heat exchanger 26. However, the fifth heat exchanger 26 is configured to dissipate heat using the outside air flow 27. In order to efficiently increase the pressure of the second heat exchanger 12 while keeping the heat transfer fluid hot, the shutter device 28 is in the closed position to prevent the passage of the outside air flow 27 through the fifth heat exchanger 26 and thus avoid dissipating heat from the hot heat transfer fluid and to efficiently increase the pressure of the second heat exchanger 12.

[0078] Of course, the invention is not limited to the examples just described and many modifications can be made to these examples without departing from the scope of the invention.

[0079] The invention, as described above, achieves its intended purpose and provides a heat treatment method for a heat treatment system that prevents refrigerant return without a fluid control device. Variations not described here could be implemented without departing from the scope of the invention, provided that, in accordance with the invention, they include a heat treatment method consistent with the invention.

Claims

DEMANDS 1- Heat treatment method for a heat treatment system (i) of a vehicle, the heat treatment system (i) comprising a refrigerant circuit (3) and a heat transfer fluid circuit (2), the refrigerant circuit (3) comprising a main path (4) extending between a convergence zone (7) and a divergence zone (8) and comprising a compression device (5) and a first heat exchanger (6) configured to perform heat exchange between a refrigerant circulating in the refrigerant circuit (3) and a heat transfer fluid circulating in the heat transfer fluid circuit (2), the refrigerant circuit (3) further comprising a first path (9) and a second path (10) both extending between the divergence zone (8) and the convergence zone (7),the first path (9) comprising a first expansion member (11) and a second heat exchanger (12) configured to perform a heat exchange between the refrigerant circulating in the refrigerant circuit (3) and the heat transfer fluid circulating in the heat transfer fluid circuit (2), the second path (10) comprising a second expansion member (13) and a third heat exchanger (14) configured to perform a heat exchange between the refrigerant circulating in the refrigerant circuit (3) and the heat transfer fluid circulating in the heat transfer fluid circuit (2), the heat transfer fluid circuit (2) comprising a first sub-circuit (16) provided with a first pumping device (18), the first heat exchanger (6) and the second heat exchanger (12), and a second sub-circuit (17) comprising a second pumping device (20) and the third heat exchanger (14),characterized in that the heat treatment process comprises a main step in which the pressure is increased within the second heat exchanger (12) while the first expansion device (11) is closed. 2- Heat treatment process according to claim 1, wherein the main step of the process comprises the following substeps: the first expansion device (11) is closed and refrigerant fluid is circulated in the refrigerant fluid circuit (3), Heat transfer fluid is circulated within the second sub-circuit (17), heat transfer fluid is circulated within the first sub-circuit (16), the heat transfer fluid circulating at least within the first heat exchanger (6) and the second heat exchanger (12). 3- Heat treatment process according to claim 1 or 2, wherein the main step is carried out for a period of between 30 and 120 seconds. 4- Heat treatment method according to any one of the preceding claims, implemented by the heat treatment system (1) in which the first sub-circuit (16) comprises a divergence point (23) disposed on the first sub-circuit (16) between the first heat exchanger (6) and the second heat exchanger (12) and a fourth heat exchanger (22) configured to carry out heat exchange between the heat transfer fluid and an interior airflow (24) intended to be sent into the passenger compartment of the vehicle, during which the heat transfer fluid circulates within the first heat exchanger (6) and then divides into a first fraction circulating within the second heat exchanger (12) and a second fraction circulating within the fourth heat exchanger (22), the first fraction and the second fraction dividing at the divergence point (23). 5- Heat treatment method according to the preceding claim, implemented by the heat treatment system (1) in which the first sub-circuit (16) comprises a fifth heat exchanger (26) configured to perform a heat exchange between the heat transfer fluid and an outside airflow (27), the heat treatment system (1) comprising a shutter device (28) configured to switch at least between an open position and a closed position to respectively permit or prohibit the passage of the outside airflow (27) through the fifth heat exchanger (26), the heat treatment method comprising a sub-step in which the shutter device (28) is closed. 6- Heat treatment method according to the preceding claim, implemented by the heat treatment system (i) in which the first sub-circuit (16) comprises an air conditioning branch (29) fluidly connected to the second heat exchanger (12), the air conditioning branch (29) comprising a sixth heat exchanger (30) configured to operate a heat exchange between the heat transfer fluid and the indoor airflow (24). 7- Heat treatment method according to the preceding claim, implemented by the heat treatment system (1) in which the second sub-circuit (17) comprises a seventh heat exchanger (31) configured to thermally treat an electrical storage device of the vehicle. 8- Heat treatment method according to the preceding claim, implemented by the heat treatment system (1) in which the second sub-circuit (17) includes a bypass branch (33) extending in parallel with the seventh heat exchanger (31). 9- Heat treatment method according to claim 7 or 8, implemented by the heat treatment system (1) in which the heat transfer fluid circuit (2) includes a cooling branch (34) provided with an eighth heat exchanger (36) configured to heat treat an electric motor of the vehicle, the cooling branch (34) being fluidly connected to the first sub-circuit (16). 10- Heat treatment method according to the preceding claim, implemented by the heat treatment system (1) in which the heat transfer fluid circuit (2) comprises a first connecting branch (37) and a second connecting branch (38) fluidly linking the cooling branch (34) to the second sub-circuit (17)- 11- Heat treatment method according to any one of the preceding claims, implemented by the heat treatment system (1) in which the second sub-circuit (17) includes an electric heating element (32) for the heat transfer fluid. 12- Heat treatment method according to any one of the preceding claims, implemented by the heat treatment system (i) in which the refrigerant fluid circuit (3) is devoid of a fluid control device on the first path (9) between the second heat exchanger (12) and the convergence zone (7).

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