Heat management system for a vehicle

Abstract

The invention relates to a heat management system (1) for a vehicle, comprising a refrigerant circuit (2) and a heat-transfer fluid circuit (3), the refrigerant circuit (2) comprising a first heat exchanger (5) and a second heat exchanger (7), the heat-transfer fluid circuit (3) comprising a loop (10) and a third heat exchanger (12), characterized in that the heat-transfer fluid circuit (3) comprises a first branch (14) comprising the second heat exchanger (7) and extending between a point of divergence (15), which is arranged on the loop (10) between an outlet (17) of the first heat exchanger (5) and the third heat exchanger (12), and a point of convergence (16), which is arranged on the loop (10) between an inlet (20) of the first heat exchanger (5) and the third heat exchanger (12).

Description

[0001] DESCRIPTION

[0002] Title of the invention: Thermal management system for a vehicle. The present invention relates to the field of motor vehicles, and more particularly concerns a thermal management system integrated within said motor vehicles.

[0003] Motor vehicles are commonly equipped with a refrigerant circuit and at least one heat transfer fluid circuit, both used to manage the temperature of different areas or components within the vehicle. It is particularly well known that the refrigerant and / or heat transfer fluid circuits are used to control the temperature of the airflow delivered to the passenger compartment of vehicles equipped with such a system. This temperature management is achieved primarily through the circulation of the refrigerant within a ventilation, heating, and / or air conditioning system installed in the vehicle.

[0004] The thermal management system typically includes a refrigerant circuit, a primary heat transfer fluid circuit, and a secondary heat transfer fluid circuit. These two heat transfer fluid circuits exchange heat with the refrigerant circuit via, respectively, a primary and a secondary heat exchanger. Typically, the refrigerant circuit also includes an expansion device, which expands the refrigerant, and a compression device, which compresses it.

[0005] More specifically, the refrigerant follows a thermodynamic cycle: it is first compressed by the compressor, which increases its pressure and temperature. Next, it is condensed in the first heat exchanger, where the heat exchange lowers its temperature while simultaneously raising the temperature of the heat transfer fluid in the first heat transfer fluid circuit. This heat is then transferred to the airflow intended to heat the vehicle's passenger compartment.

[0006] The refrigerant is then expanded by the expansion valve, which lowers its pressure and temperature, before passing into the second heat exchanger, where it absorbs heat and evaporates. It then returns to the compression unit for another thermodynamic cycle. Compression by the compression unit requires a certain amount of energy, which depends in particular on the pressure and temperature of the refrigerant upstream and downstream of the compression unit, as well as the mass flow rate of the refrigerant.

[0007] In the prior art, the second heat transfer fluid circuit typically recovers heat from a heat source to facilitate the evaporation of the refrigerant in the second heat exchanger. However, in some cases, these heat sources may not be available, or they may have a very low thermal potential, which significantly reduces the heating energy and the system's efficiency. A solution in the prior art proposes recovering heat from a hot liquid resulting from the condensation of the thermodynamic cycle. This liquid, after being used to heat the passenger compartment, is then sent to the second heat exchanger arranged in the refrigerant circuit to serve as a heat source.

[0008] The drawback of this solution is that, after heating the passenger compartment, the hot liquid contains little or no heat. Consequently, its impact on the second heat exchanger is limited, making it ineffective as a heat source.

[0009] The invention fits within this context by presenting a solution that exploits the calories from the thermodynamic cycle more efficiently, thus improving the performance of the thermal management system.

[0010] The present document proposes a thermal management system for vehicles comprising a refrigerant circuit intended to be traversed by a refrigerant and a heat transfer fluid circuit intended to be traversed by a heat transfer fluid, the refrigerant circuit comprising a compression device, an expansion device, a first heat exchanger and a second heat exchanger, the first heat exchanger and the second heat exchanger being configured to perform heat exchange between the refrigerant and the heat transfer fluid, the heat transfer fluid circuit comprising a loop including the first heat exchanger, a pumping device and a third heat exchanger configured to perform heat exchange between the heat transfer fluid and an interior airflow intended to be sent into a vehicle passenger compartment,characterized in that the heat transfer fluid circuit comprises a first branch carrying the second heat exchanger and extending between a divergence point and a convergence point, the divergence point being located on the loop between an outlet of the first heat exchanger and the third heat exchanger, the convergence point being located on the loop between an inlet of the first heat exchanger and the third heat exchanger.

[0011] The invention therefore includes a branch diverting part of the heat transfer fluid from the second heat transfer fluid circuit, such a branch being connected to the first heat transfer fluid circuit so as to use the heat transfer fluid as a heat source for the second heat exchanger.

[0012] Such a thermal management system can therefore be used to heat a vehicle's passenger compartment. By heating the second heat exchanger with the heat transfer fluid circulating in the first branch, the pressure of the refrigerant within this second heat exchanger increases, which also allows for an increase in the rotational speed of the compressor. The thermodynamic cycle can then take place and provide heat through the change of state of the refrigerant.

[0013] The refrigerant can, for example, be a refrigerant with the acronym R290, which is propane. This is a two-phase refrigerant that is compressed and circulated in vapor form by the compression device. The refrigerant then passes through the first heat exchanger, the expansion chamber, and the second heat exchanger in that order, to complete the thermodynamic cycle.

[0014] Thus, the high-pressure, high-temperature refrigerant condenses as it passes through the first heat exchanger, transferring heat to the heat transfer fluid also circulating within it. The refrigerant is then expanded by the expansion valve and is at a low pressure. Finally, the refrigerant evaporates as it circulates through the second heat exchanger, and this change of state cools the heat transfer fluid also circulating within the second heat exchanger. The evaporated refrigerant can then be compressed again by the compressor to begin a new thermodynamic cycle and participate in the functions of the thermal management system. The heat transfer fluid circulating in the heat transfer fluid circuit can be a liquid, such as glycol water, circulated in the loop by the first pumping device.This heat transfer fluid recovers the heat resulting from the change of state of the refrigerant within the first heat exchanger. It should be noted that this first heat exchanger can be a dual-fluid exchanger, acting as a condenser for the refrigerant circuit.

[0015] Upon exiting the first heat exchanger, the heat transfer fluid is divided into two fractions: one that continues circulating in the loop and a second that flows into the first branch from the point of divergence. This second fraction then passes through the second heat exchanger, where it heats the low-pressure, low-temperature refrigerant from the expansion valve before rejoining the first fraction at the point of convergence. The second heat exchanger can therefore be a low-pressure, two-fluid exchanger, acting as an evaporator.

[0016] The first portion of the heat transfer fluid circulates to the third heat exchanger, which is integrated into a ventilation, heating, and / or air conditioning system, thus contributing to heating the vehicle's passenger compartment. The interior airflow passes through this exchanger and absorbs heat from the heat transfer fluid, then is sent into the passenger compartment to heat it. Therefore, the third heat exchanger acts as a radiator to heat the vehicle's passenger compartment. In other words, the point of divergence, located between the outlet of the first heat exchanger and the third heat exchanger, allows the heat transfer fluid to separate into these two previously mentioned portions, after it has absorbed heat from the refrigerant in the first heat exchanger.The first fraction heats the indoor airflow via the third heat exchanger, while the second fraction heats the refrigerant via the second heat exchanger.

[0017] It should be noted that, since the first point of divergence is positioned between the first heat exchanger and the third heat exchanger, this allows the heat transfer fluid circulating in this first branch to contain a maximum of calories, in order to optimize the heating of the refrigerant fluid in the second heat exchanger.

[0018] This increase in the refrigerant's temperature raises its pressure in the second heat exchanger, and consequently, its pressure at the inlet of the compressor. As a result, the compressor can deliver a higher flow rate of refrigerant at a constant velocity, allowing the passenger compartment to heat up more quickly.

[0019] The convergence point, located between the third heat exchanger and the inlet of the first heat exchanger, allows the two fractions to mix after releasing heat through exchanges with the internal airflow and the refrigerant. The recombined heat transfer fluid is then returned to the first heat exchanger to recover heat again through exchange with the refrigerant.

[0020] In summary, the first branch diverts a portion of the heated heat transfer fluid from the first heat exchanger, circulating it through the second heat exchanger. This allows the fluid to be used as a heat source for the refrigerant. Thanks to this configuration, the heated heat transfer fluid evaporates the refrigerant, thus increasing the pressure. This, in turn, increases the density of the refrigerant entering the compression unit, resulting in a higher flow rate at a given operating speed. Consequently, at the same speed, the passenger compartment is heated more effectively, making the thermal management system more efficient.According to an optional feature of the invention, the heat transfer fluid circuit includes a second branch carrying a fourth heat exchanger configured to operate a heat exchange between the heat transfer fluid and a fluid, the second branch extending between a separation point and a junction point disposed on the first branch.

[0021] The separation point is a point allowing the separation of the heat transfer fluid circulating upstream of this point, and the junction point is a point allowing the reunification of the heat transfer fluid circulating upstream of this point. Regarding their arrangement, being located on the first branch, it should be understood that it is the heat transfer fluid circulating in the first branch that is separated.

[0022] The fourth heat exchanger is designed to perform heat exchange between the heat transfer fluid circulating in the second branch and an external flow. This flow could be, for example, an outside airflow from an external environment or a fluid from the vehicle's powertrain, such as glycol water. It is therefore understood that the fourth heat exchanger acts, for example, as an external radiator for the thermal management system, that is, a radiator that exchanges heat with an external airflow outside the passenger compartment.

[0023] It should be noted that to facilitate the circulation of the heat transfer fluid within the second branch and the first branch, the thermal management system includes a second pumping device, located for example in the second branch.

[0024] Therefore, it is important to understand that the fourth heat exchanger heats the heat transfer fluid circulating in the second branch, which in turn heats the refrigerant circulating in the second heat exchanger. Consequently, the fourth heat exchanger acts as a heat source.

[0025] We can therefore identify two potential heat sources: on the one hand, the heat transfer fluid in the third heat exchanger heated by the refrigerant in the first heat exchanger, and on the other hand, the heat transfer fluid heated by the outside air or the fluid from the vehicle's powertrain via the fourth heat exchanger.

[0026] Under certain conditions, the fourth heat exchanger may be unavailable, for example, when dealing with an outdoor radiator that can freeze. This can occur, in particular, when the outside environment is so cold that frost forms, preventing air from passing through the fourth heat exchanger and thus blocking heat transfer.

[0027] As a first effect, the thermal management system always maintains a heat source: the heat transfer fluid circulating in the first branch, which is heated by the refrigerant in the third heat exchanger. This allows it to continue operating even when the fourth heat exchanger is inoperative.

[0028] According to a second effect, the calories from the heat transfer fluid circulating in the first branch, which passes through the second heat exchanger, are used to heat, at least partially, the fourth heat exchanger in order to allow defrosting of the fourth heat exchanger.

[0029] According to an optional feature of the invention, the separation point is disposed between the convergence point and the second heat exchanger, the junction point being disposed on the first branch between the second heat exchanger and the divergence point.

[0030] It is thus understood that the second fraction is separated at the outlet of the second heat exchanger, after exchanging its heat with the refrigerant at the separation point, into a first and a second flow. The second flow is then sent to the fourth heat exchanger, for example, to recover heat from the outside air stream.

[0031] The second stream is then mixed with the second fraction at the junction point before passing back into the second heat exchanger to heat the refrigerant.

[0032] The first flow circulates in the first branch, from the point of separation to the point of convergence, and is mixed with the first fraction before being heated by the refrigerant at the first heat exchanger.

[0033] It is understood here that the second flow is used to recover heat from the external environment. The second fraction, heated by its interaction with the refrigerant in the first heat exchanger, mixes with the second flow. This mixture is then used to heat the refrigerant. As mentioned previously, this promotes a pressure increase in the refrigerant, on the low-pressure side of the thermodynamic cycle.

[0034] It is worth noting that even if the fourth heat exchanger is frozen, the second heat exchanger can still function thanks to the presence of the second fraction, which continues to circulate and provide heat. Furthermore, at the outlet of the second heat exchanger, the mixture of the second flow and the second fraction may still contain heat, particularly due to residual heat from the second fraction. This heat can then be used to thaw the fourth heat exchanger.

[0035] According to an optional feature of the invention, the fluid with which the heat transfer fluid exchanges within the fourth heat exchanger is an airflow from outside the vehicle's passenger compartment or a fluid from a drivetrain of said vehicle.

[0036] Indeed, the fourth heat exchanger can be used in applications other than heat recovery from an outside airflow. It can, for example, be used to recover heat generated by the vehicle's engine. It should be noted that the invention remains advantageous even in this application, since the first branch of the invention leads to an increase in the refrigerant pressure, which improves the efficiency of the thermal management system.

[0037] According to an optional feature of the invention, the second branch includes a one-way valve or check valve, configured to allow circulation of the heat transfer fluid from the point of separation to the point of junction, and to prevent circulation of the heat transfer fluid from the point of junction to the point of separation.

[0038] The one-way valve or non-return valve is located between an outlet of the fourth heat exchanger and the junction point or between the separation point and an inlet of the fourth heat exchanger.

[0039] The one-way valve or non-return valve thus prevents unwanted circulation of the heat transfer fluid in the second branch when the second pumping device of the second branch is stopped.

[0040] According to an optional feature of the invention, the first branch includes at least one valve. The valve is used to control the flow of the heat transfer fluid in the first branch. This valve allows the flow of the heat transfer fluid in this first branch to be blocked or, conversely, to be allowed to pass. It should be noted that when the heat transfer fluid is blocked in the first branch, it does not separate at the point of divergence. Consequently, all of the heat transfer fluid passing through the first heat exchanger circulates in the loop and passes into the third heat exchanger.

[0041] According to an optional feature of the invention, the valve is disposed between the divergence point and an inlet of the second heat exchanger or between the convergence point and an outlet of the second heat exchanger.

[0042] The heat transfer fluid circulating in the second branch, from the second heat exchanger to the fourth heat exchanger, cannot mix with the fluid circulating in the loop because the valve is closed. This heat transfer fluid circulating in the second branch forms a kind of second loop, independent of the previously described loop, circulating from the separation point to the fourth heat exchanger, then from the fourth heat exchanger to the junction point, before returning to the second heat exchanger and then reaching the separation point and restarting the cycle in the same way.

[0043] According to an optional feature of the invention, the valve is a proportional valve.

[0044] The use of a proportional valve allows control of the amount of heat transfer fluid in the second portion sent to the second heat exchanger. The valve thus controls the flow rate of the heat transfer fluid in intermediate positions between fully open and fully closed.

[0045] According to an optional feature of the invention, the valve is an on / off valve. This allows for simple control of the thermal management system.

[0046] According to an optional feature of the invention, an additional pumping device replaces the valve.

[0047] According to an optional feature of the invention, the first heat exchanger operates as a condenser, the second heat exchanger operates as an evaporator, and the third heat exchanger is a radiator for heating the vehicle's passenger compartment. The invention therefore also covers a method for managing the thermal performance of a vehicle, implemented by a thermal management system as described above, in which:

[0048] The refrigerant is circulated in the refrigerant circuit, the refrigerant circulating in a loop successively through the compression device, the first heat exchanger, the expansion device, and the second heat exchanger.

[0049] The heat transfer fluid is circulated within the loop of the heat transfer fluid circuit.

[0050] The heat transfer fluid circulating in the loop is separated into two fractions of heat transfer fluid at the point of divergence, a first fraction of heat transfer fluid circulating in the loop and passing through the third heat exchanger, a second fraction of heat transfer fluid circulating in the first branch and passing through the second heat exchanger, the first fraction and the second fraction of heat transfer fluid are mixed at the point of convergence.

[0051] Such a thermal management process ensures more efficient temperature control of the passenger compartment than prior art systems, by allowing the compression device to operate at a higher pressure level on the low-pressure side of the thermodynamic cycle.

[0052] According to an optional feature of the invention, during the implementation of the thermal management process as described above:

[0053] The second fraction is separated into two heat transfer fluid streams at the separation point: a first stream of heat transfer fluid circulates in the first branch, and a second stream circulates in the second branch and passes through the fourth heat exchanger. The second stream and the second fraction of heat transfer fluid are mixed at the junction point. According to an optional feature of the invention, the thermal management method as described above is implemented when the fourth heat exchanger is inoperative, particularly due to clogging caused by freezing. 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 accompanying schematic drawings, on the other hand, in which:

[0054] [fig 1] is a schematic representation of a first embodiment of a thermal management system according to the invention,

[0055] [Fig. 2] is a schematic representation of a first operating mode of a second embodiment of the thermal management system,

[0056] [fig 3] is a schematic representation of a second operating mode of the second embodiment of the thermal management system.

[0057] The list of these embodiments is not exhaustive, and a number of other, unillustrated embodiments may be implemented within the thermal management system 1. In each figure, solid lines indicate the circulation of a heat transfer fluid, while dashed lines represent the circulation of a refrigerant. The direction of heat transfer fluid flow is further indicated by arrows.

[0058] Figure 1 shows a first embodiment of a thermal management system 1 according to the invention, which can be integrated into a motor vehicle. This thermal management system 1 is particularly suitable for providing thermal management of the vehicle's passenger compartment, i.e., heating or cooling of the passenger compartment.

[0059] To do this, the thermal management system 1 includes a refrigerant circuit 2 in which a refrigerant circulates and a heat transfer fluid circuit 3 in which a heat transfer fluid circulates.

[0060] The thermal management system 1 is configured to operate various interactions between the heat transfer fluid and the refrigerant in order to optimally manage the vehicle's interior temperature. The heat transfer fluid can, for example, be glycol water, while the refrigerant can be, for example, an R290 type refrigerant, i.e., propane, which meets European environmental standards.

[0061] The refrigerant circuit 2 consists of a single closed channel, equipped with a compression device 4 that circulates the refrigerant in the refrigerant circuit 2, a first heat exchanger 5, an expansion device 6 and a second heat exchanger 7. The first heat exchanger 5 and the second heat exchanger 7 are configured to perform a heat exchange between the refrigerant circulating in the refrigerant circuit 2 and the heat transfer fluid circulating in the heat transfer fluid circuit 3. The expansion device 6 ensures a reduction in the pressure of the refrigerant which then generates an expansion of it.

[0062] The circulation of the refrigerant and heat transfer fluid in the second heat exchanger 7 is co-current. Alternatively, the circulation of the refrigerant and heat transfer fluid in the second heat exchanger 7 is counter-current.

[0063] The refrigerant operates according to a thermodynamic cycle, first being compressed by the compression device 4, which increases its pressure and temperature. The refrigerant is then condensed within the first heat exchanger 5. The heat exchange occurring within the first heat exchanger 5 causes a decrease in the temperature of the refrigerant, which is then condensed, while simultaneously causing a rise in the temperature of the heat transfer fluid also circulating within the first heat exchanger 5.

[0064] It should therefore be noted that the first heat exchanger 5 is, in this embodiment, a high-pressure two-fluid heat exchanger used as a condenser.

[0065] Upon exiting the first heat exchanger 5, the refrigerant is then expanded by the expansion valve 6, resulting in a drop in refrigerant pressure. It then passes through the second heat exchanger 7. The refrigerant is evaporated within this second heat exchanger 7.

[0066] The heat exchange occurring within the second heat exchanger 7 results in a supply of heat to the refrigerant fluid which is then evaporated, while also causing a decrease in the temperature of the heat transfer fluid circulating simultaneously within the second heat exchanger 7. The second heat exchanger 7 is therefore here a low pressure two-fluid heat exchanger used as an evaporator.

[0067] The heat transfer fluid circuit 3 comprises a loop 10 equipped with a first pumping device 11, a first heat exchanger 5, and a third heat exchanger 12. The first pumping device 11 circulates the heat transfer fluid within the loop 10. As previously described, the first heat exchanger 5 increases the temperature of the heat transfer fluid through heat exchange with the refrigerant. The third heat exchanger 12 is configured to perform heat exchange between the heat transfer fluid and an interior airflow 13 passing through said third heat exchanger 12. The interior airflow 13 is then intended to circulate to the vehicle's passenger compartment.It is thus understood that the heat transfer fluid heats the interior airflow 13 passing through the third heat exchanger 12, and the heated interior airflow 13 subsequently heats the vehicle's passenger compartment. Therefore, the third heat exchanger 12 is, for example, located within a ventilation, heating, and / or air conditioning system not shown in the figures.

[0068] The heat transfer fluid circuit 3 also includes a first branch 14. The first branch 14 extends between a divergence point 15 and a convergence point 16.

[0069] In this embodiment, the divergence point 15 is located on the loop 10 between an outlet 17 of the first heat exchanger 5 and an inlet 18 of the third heat exchanger 12. More particularly, the divergence point 15 is arranged between the first pumping device 11 and the inlet 18 of the third heat exchanger 12.

[0070] The convergence point 16 is located on the loop 10, between an outlet 19 of the third heat exchanger 12 and an inlet 20 of the first heat exchanger 5. It is therefore understood that within the loop 10, the heat transfer fluid is put into circulation by the first pumping device 11 and circulates from the outlet 17 of the first heat exchanger 5 to the inlet 18 of the third heat exchanger 12, then from the outlet 19 of the third heat exchanger 12 to the inlet 20 of the first heat exchanger 5.

[0071] The first branch 14 is equipped with the second heat exchanger 7. This second heat exchanger 7 is positioned in the first branch 14 between the divergence point 15 and the convergence point 16, so that the heat transfer fluid circulating in the first branch 14 passes through the second heat exchanger 7.

[0072] As mentioned previously, this second heat exchanger 7 is configured to allow heat exchange between the heat transfer fluid and the refrigerant. It is therefore understood that the heat transfer fluid circulating in the first branch 14 heats the refrigerant within the second heat exchanger 7.

[0073] The first branch 14 is also equipped with at least one valve 21. This valve 21 allows control of the heat transfer fluid circulating in the first branch 14. It is understood that thanks to this valve 21, it is possible to choose whether or not to supply the first branch 14 with heat transfer fluid, and therefore to supply or not the second heat exchanger 7.

[0074] As an example, this valve 21 can be an on / off valve, that is to say a valve which can be either in the open position, thus allowing the circulation of the heat transfer fluid in the first branch 14, or in the closed position, thus preventing the circulation of the heat transfer fluid in the first branch 14, without being able to take an intermediate position between this open position and this closed position.

[0075] Valve 21 can also be a proportional valve. In this case, valve 21 includes not only an open position and a closed position, but also a multitude of intermediate positions, which then allows the circulation of the heat transfer fluid within the first branch 14 to be modulated.

[0076] The valve 21 can be positioned at different locations in the first branch 14. In this embodiment, the valve 21 is arranged in a first part 22 of the first branch 14. This first part 22 corresponds to the section of the first branch 14 that extends between the divergence point 15 and an inlet 23 of the second heat exchanger 7. It should be noted that the first branch 14 also includes a second part 24, which extends between an outlet 25 of the second heat exchanger 7 and the convergence point 16.

[0077] Alternatively, the valve 21 could be positioned on the second part 24 of the first branch 14, or the thermal management system 1 could include a second valve, in addition to the valve 21, arranged in this second part 24 of the first branch 14.

[0078] In this embodiment, the valve 21 is shown open, or in a position allowing the heat transfer fluid to circulate in the first branch; the heat transfer fluid is then split at the point of divergence 15. More precisely, the heat transfer fluid is divided into a first fraction and a second fraction at this point of divergence 15.

[0079] It should be noted that the valve 21 can however take a closed position in which the circulation of the heat transfer fluid is blocked in the first branch 14, since the valve 21 is positioned within the first branch 14. It is then understood that, when the valve 21 is closed, the heat transfer fluid simply circulates within the loop 10 without being divided at the point of divergence 15.

[0080] The first fraction continues its circulation in loop 10 in the same way that the heat transfer fluid would if valve 21 were closed. It is therefore understood that the first fraction circulates from outlet 17 of the first heat exchanger 5 to inlet 18 of the third heat exchanger 12, then from outlet 19 of the third heat exchanger 12 to inlet 20 of the first heat exchanger 5.

[0081] The second fraction corresponds to the heat transfer fluid circulating in the first branch 14. Thus, the second fraction circulates in the first part 22 of the first branch 14, from the divergence point 15 to the inlet 23 of the second heat exchanger 7, then in the second part 24 of the first branch 14, from the outlet 25 of the second heat exchanger 7 to the convergence point H. It should be noted that the flow rates of the first and second fractions depend on the position of the valve 21 when it is a proportional valve. Indeed, the more heat transfer fluid the valve 21 allows to pass, the greater the flow rate of the second fraction will be, and the lower that of the first fraction will be. Conversely, the less heat transfer fluid the valve 21 allows to pass, the greater the flow rate of the first fraction will be and the lower that of the second fraction.

[0082] The convergence point 16 allows the second fraction of the heat transfer fluid to be recirculated within the loop 10. It is therefore understood that at the convergence point 16, the second fraction is mixed with the first fraction circulating in the loop 10.

[0083] In this context, the mixture of the first and second fractions then passes from the convergence point 16 to the inlet 20 of the first heat exchanger 5. It is this mixture, composed of the first and second fractions, that exchanges heat with the high-pressure, high-temperature refrigerant within the first heat exchanger 5, and is thus heated. At the outlet of the first heat exchanger 5, a mixture of the first and second fractions is obtained, having absorbed heat from the refrigerant. This mixture flows from the outlet 17 of the first heat exchanger 5 to the divergence point 15, before being separated once again into the first and second fractions at the divergence point 15, while the refrigerant remains at high pressure and low temperature.

[0084] It is therefore understood that at the entrance of the third heat exchanger 12, the first fraction contains calories, then discharges them into the internal airflow 13. The first fraction of the heat transfer fluid is then cooled when it exits the third heat exchanger 12.

[0085] Simultaneously, at the inlet of the second heat exchanger 7, the second fraction includes calories, then exchanges them with the low-pressure, low-temperature refrigerant fluid within the second heat exchanger 7.

[0086] At the convergence point 16, the first and second fractions are therefore mostly devoid of calories at this point, before being mixed and enriched with calories within the first heat exchanger 5. In other words, from the outlet 17 of the first heat exchanger 5 to the divergence point 15, the mixture of the first and second fractions contains calories. From the divergence point 15 to the inlet 23 of the second heat exchanger 7, the second fraction contains calories, and from the divergence point 15 to the inlet 18 of the third heat exchanger 12, the first fraction also contains calories. From the outlet 25 of the second heat exchanger 7 to the convergence point 16, the second fraction is mostly devoid of calories, and from the outlet 19 of the third heat exchanger 12, the first fraction is mostly devoid of calories.From the convergence point 16 to the inlet 20 of the first heat exchanger 5, the mixture of the first and second fractions is also devoid of heat. Regarding the refrigerant, between the compression device 4 and the first heat exchanger 5, it is at high temperature and high pressure. Between the first heat exchanger 5 and the expansion valve 6, it is at low temperature and high pressure. Between the expansion valve 6 and the second heat exchanger 7, it is at low temperature and low pressure. Finally, between the second heat exchanger 7 and the compression device 4, it is at high temperature and low pressure.

[0087] Thus, in this embodiment of the thermal management system 1, it is understood that the refrigerant heats the heat transfer fluid through the first heat exchanger 5, and that the second fraction of this heat transfer fluid containing calories then heats the refrigerant within the second heat exchanger 7, while the first fraction of this heat transfer fluid containing calories also heats the indoor airflow 13 within the third heat exchanger 12. These two fractions are therefore then mixed, then heated by the first heat exchanger 5.

[0088] This cycle therefore operates independently of any external heat source to the thermal management system 1, by providing heating of the refrigerant using the calories present in the heat transfer fluid heated by said refrigerant.

[0089] Figure 2 is a schematic representation of a first operating mode of a second embodiment of the thermal management system 1 according to the invention. This thermal management system 1 can also be integrated within a motor vehicle and be capable of providing thermal management for the vehicle's passenger compartment.

[0090] This embodiment shares similarities with the first embodiment. The second embodiment is a thermal management system 1 comprising a refrigerant circuit 2 with the same components as those described previously. It also includes a heat transfer fluid circuit 3, which has a loop 10 and a first branch 14, arranged in the same manner as in the first embodiment and comprising the same components. The difference between this second embodiment and the first embodiment lies in the presence of a second branch 26 within the heat transfer fluid circuit 3.

[0091] The second branch 26 is fluidically connected to the first branch 14. This second branch 26 extends between a separation point 27 and a junction point 28. The separation point 27 and the junction point 28 are arranged on the first branch 14.

[0092] More precisely, the separation point 27 is positioned on the second part 24 of the first branch 14, that is to say between the outlet 25 of the second heat exchanger 7 and the convergence point 16.

[0093] The junction point 28 is, for its part, located on the first part 22 of the first branch 14, that is to say between the divergence point 15 and the inlet 23 of the second heat exchanger 7.

[0094] The second branch 26 includes a fourth heat exchanger 29 in the thermal management system 1. It is therefore understood that when heat transfer fluid circulates in the second branch 26, it then passes through this fourth heat exchanger 29.

[0095] In this embodiment, this fourth heat exchanger 29 is an external radiator designed to exchange heat between the heat transfer fluid circulating in the second branch 26 and an external airflow 30 from an environment outside the vehicle's passenger compartment.

[0096] In other embodiments of the invention, the fourth heat exchanger 29 could be designed to perform heat exchange between the heat transfer fluid and a fluid from the vehicle's powertrain, instead of exchange with the outside airflow 30. It should be noted that, even in these other embodiments, the thermal management system 1 can also operate according to the operating modes that will be described later.

[0097] The second branch 26 comprises two portions. A first portion 31 extends between the separation point 27 and an inlet 32 ​​of the fourth heat exchanger 29. A second portion 33 extends between an outlet 34 of the fourth heat exchanger 29 and the junction point 28.

[0098] The second branch 26 carries a second pumping device 35. This second pumping device 35 is, in this second embodiment, arranged on the first portion 31 of the second branch 26, that is to say between the separation point 27 and the inlet 32 ​​of the fourth heat exchanger 29.

[0099] In this embodiment, the second branch 26 includes a one-way valve or check valve 36, configured to allow circulation of the heat transfer fluid from the separation point 27 to the junction point 28, and to prevent circulation of the heat transfer fluid from the junction point 28 to the separation point 27.

[0100] The one-way valve or non-return valve 36 is arranged between the outlet 34 of the fourth heat exchanger 29 and the junction point 28. Alternatively, the one-way valve or non-return valve 36 is arranged between the separation point 27 and the inlet 32 ​​of the fourth heat exchanger 29.

[0101] The one-way valve or non-return valve 36 thus prevents unwanted circulation of the heat transfer fluid in the second branch 26 when the second pumping device 35 of the second branch 26 is stopped.

[0102] It should be noted that in this embodiment, the thermal management system 1 can operate in different modes, depending on the position of the valve 21 and the availability of the fourth heat exchanger 29.

[0103] In the first operating mode illustrated in this figure 2, the valve 21 is in the open position, or is in any position allowing the circulation of the heat transfer fluid in the first branch 14.H. It should be noted that the first operating mode is activated when the fourth heat exchanger 29 is unavailable, for example due to its icing, and / or when the pressure within the second heat exchanger 7 is too low, which therefore causes the opening of the valve 21 to ensure the circulation of the heat transfer fluid in the first branch 14.

[0104] The heat transfer fluid is then, as in the first embodiment, divided into a first fraction which continues its path in the loop 10 and a second fraction which circulates in the first branch 14.

[0105] The first fraction circulates in the loop 10, exchanges heat with the internal airflow 13, then mixes with the heat transfer fluid from the first branch 14 at the point of convergence 16, before starting a new cycle.

[0106] In this first operating mode, the second fraction circulates in the first part 22 of the first branch 14, from the divergence point 15 to the inlet 23 of the second heat exchanger 7, where it exchanges its heat with the refrigerant. Then, it passes from the outlet 25 of the second heat exchanger 7 to the separation point 27.

[0107] This first operating mode therefore has the advantage of using the heat transfer fluid as a heat source in the thermodynamic cycle thanks to the second fraction of this heat transfer fluid. By heating the refrigerant with this second fraction, which is itself heated by the refrigerant, the pressure of the refrigerant in the second heat exchanger 7 is increased more rapidly. This leads to an increase in the density of the refrigerant at the inlet of the compression device 4, thus allowing the compression device 4 to deliver a higher flow rate at a constant speed, thereby improving the efficiency of the thermal management system 1.

[0108] Thus, whether the first operating mode is activated due to insufficient pressure in the second heat exchanger 7 or due to the fourth heat exchanger 29 being inoperative, this first operating mode increases the pressure within the second heat exchanger 7, thereby contributing to making the thermal management system 1 more efficient. At the separation point 27, i.e., at the outlet of the second heat exchanger 7, the second fraction of heat transfer fluid, which is then mostly devoid of heat after the heat exchange with the refrigerant, divides again. One flow remains in the second part 24 of the first branch 14 and continues its path to the convergence point 16, while a second flow departs in the first portion 31 of the second branch 26, thus circulating from the separation point 27 to the inlet 32 ​​of the fourth heat exchanger 29.When the first operating mode is activated due to insufficient pressure in the second heat exchanger 7, but the fourth heat exchanger 29 is operational, this second flow then exchanges heat with the external environment through heat exchange with the outside air flow 30 within the fourth heat exchanger 29. At the outlet of the fourth heat exchanger 29, the second flow has therefore recovered calories from the outside air 30.

[0109] When the first operating mode is activated due to the unavailability of the fourth heat exchanger 29, the second flow cannot exchange heat with the external environment, for example, due to the icing of this fourth heat exchanger 29. However, the second flow then facilitates the defrosting of the fourth heat exchanger 29. Indeed, even at the outlet of the second heat exchanger 7, the second fraction of the heat transfer fluid can still contain heat, and therefore the second flow can also contain heat. Thus, when this second flow reaches the iced fourth heat exchanger 29, it transfers heat, thereby contributing to its defrosting. This first operating mode therefore not only increases the pressure in the second heat exchanger 7 but also defrosts the fourth heat exchanger 29 when it is inoperative.

[0110] At the outlet of the fourth heat exchanger 29, the second flow then circulates in the second portion 33 of the second branch 26, from the outlet 34 of the fourth heat exchanger 29 to the junction point 28.

[0111] At this junction point 28, the second flow is mixed with the second fraction of heat transfer fluid coming from the divergence point 15, and this mixture then passes through the second heat exchanger 7 in order to transfer its heat to the refrigerant and repeat the cycle described.

[0112] It should be noted that when the fourth heat exchanger 29 is inoperative, the second flow exiting the fourth heat exchanger 29 is free of calories, as these have been used for defrosting the fourth heat exchanger 29. On the other hand, when the first operating mode is activated to increase the pressure of the second heat exchanger 7 and the fourth heat exchanger 29 is operational, the second flow exiting the latter contains calories recovered from the outside air flow.

[0113] Thus, when the fourth heat exchanger 29 is inoperative, the second heat-free stream mixes with the second fraction, which contains heat. The resulting mixture therefore includes heat from the second fraction, which will be exchanged with the refrigerant within the second heat exchanger 7. When the first operating mode is used to increase the pressure of the second heat exchanger 7 and the fourth heat exchanger 29 is available, the second stream contains heat and mixes with the second fraction, which also contains heat. The resulting mixture thus includes heat from both the second stream and the second fraction, which will then be exchanged with the refrigerant within the second heat exchanger 7.

[0114] Regarding the first flow, it circulates from the separation point 27 to the convergence point 16, where it is mixed with the first fraction, before this mixture circulates in the first heat exchanger 5 to recover heat from the refrigerant.

[0115] In other words, the heat transfer fluid is heated by the refrigerant within the first heat exchanger 5. Then, when the valve 21 is open or in any position allowing the heat transfer fluid to pass through the first branch 14, the first fraction and the second fraction separate, then the first fraction of the heat transfer fluid circulates in the loop 10, where it transfers its heat to the indoor airflow 13 via the third heat exchanger 12. The second fraction, meanwhile, circulates in the first branch 14 and transfers its heat to the refrigerant through the second heat exchanger 7, which has the effect of increasing the pressure within the latter.

[0116] After this exchange, the second fraction splits into two flows: the first flow joins loop 10, and the second flow recovers heat from the external environment via the fourth heat exchanger 29 or facilitates its defrosting. This second flow then joins the first branch 14 upstream of the second heat exchanger 7 and mixes with the second fraction at the junction point 28. The heat from this mixture is then transferred to the refrigerant via the second heat exchanger 7.11. It should be noted that the use of valve 21, when it is a proportional valve, allows control of the quantity of the second fraction of heat transfer fluid sent to the second heat exchanger 7, thus providing a means of regulating the pressure increase within the second heat exchanger 7, thereby controlling the efficiency of the thermal management system 1.

[0117] Figure 3 is a schematic representation of a second operating mode of the second embodiment of the thermal management system 1 according to the invention.

[0118] In this second mode of operation, the fourth heat exchanger 29 is operational, but the valve 21 of the first branch 14 is closed, which is represented in Figure 3 by the black color of said valve 21.

[0119] In this case, the heat transfer fluid in loop 10 is not divided at the divergence point 15. More precisely, closing valve 21 prevents the heat transfer fluid from circulating in part of the first branch 14, thus blocking the passage between the divergence point 15 and the junction point 28, which is represented in Figure 3 by dashed lines. This therefore prevents the heat transfer fluid from loop 10 from reaching the second heat exchanger 7 and the fourth heat exchanger 29.

[0120] The heat transfer fluid circulating in the loop 10 can therefore be defined as a first part of the heat transfer fluid, which remains in the loop 10 without being separated at the divergence point 15. This first part circulates exclusively in the loop 10, where it is heated by the refrigerant in the first heat exchanger 5, before circulating from the outlet 17 of the first heat exchanger 5 to the inlet 18 of the third heat exchanger 12, where it transfers heat to the internal airflow 13. Then, it returns from the outlet 19 of the third heat exchanger 12 to the inlet 20 of the first heat exchanger 5 to be heated again, thus completing a circulation cycle.

[0121] Simultaneously, a second part of the heat transfer fluid circulates between the second heat exchanger 7 and the fourth heat exchanger 29, recovering heat from the outside airflow 30 to transfer it to the refrigerant.

[0122] It should be noted that, since valve 21 is closed, the first part of the heat transfer fluid circulating in loop 10 is independent of the second part of the heat transfer fluid which circulates between the second heat exchanger 7 and the fourth heat exchanger 29.

[0123] The circulation of the second portion of the heat transfer fluid between the second heat exchanger 7 and the fourth heat exchanger 29 is ensured by the second pumping device 35. Through this device, the second portion of the heat transfer fluid flows from the second pumping device 35 to the inlet 32 ​​of the fourth heat exchanger 29, where it recovers heat from the outside air stream 30. Next, the heat transfer fluid flows from the outlet 34 of the fourth heat exchanger 29 to the junction point 28, and then to the inlet 23 of the second heat exchanger 7. Within this second heat exchanger, the heat transfer fluid releases the recovered heat to the outside air stream 30. After this, it flows from the outlet 25 of the second heat exchanger 7 to the separation point 27, and then from the separation point 27 back to the second pumping device 35 to begin a new cycle.

[0124] A switch from the second operating mode to the first operating mode is made in case of too low pressure in the second heat exchanger 7, or in case of unavailability of the fourth heat exchanger 29.

[0125] The refrigerant circuit 2 includes, for example, a refrigerant pressure sensor, not shown, located between the outlet of the second heat exchanger 7 and the inlet of the compression device 4. When the second operating mode is active, a pressure value measured by the pressure sensor and representative of the pressure in the second heat exchanger 7 falling below a threshold value causes the switch from the second operating mode to the first operating mode.

[0126] When the second operating mode is in use, the pressure in the second heat exchanger 7 can become very low in the event of very low ambient temperatures, and the system's performance is then limited. Activating the first operating mode restores the pressure level in the second heat exchanger 7, resulting in a satisfactory level of performance.

[0127] 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.

[0128] The invention, as described, achieves its objective by providing a thermal management system comprising a refrigerant circuit and a heat transfer fluid circuit, the latter including a loop and a first branch. The loop heats the vehicle's passenger compartment, while the first branch allows the heat transfer fluid to warm the refrigerant. Thus, the invention offers a more efficient thermal management system, capable of operating even in external conditions unfavorable to the use of a refrigerant circuit operating in heat pump mode.

Claims

DEMANDS 1. Thermal management system (1) for a vehicle comprising a refrigerant circuit (2) intended to carry a refrigerant and a heat transfer fluid circuit (3) intended to carry a heat transfer fluid, the refrigerant circuit (2) comprising a compression device (4), an expansion device (6), a first heat exchanger (5) and a second heat exchanger (7), the first heat exchanger (5) and the second heat exchanger (7) being configured to perform heat exchange between the refrigerant and the heat transfer fluid, the heat transfer fluid circuit (3) comprising a loop (10) comprising the first heat exchanger (5), a pumping device (11) and a third heat exchanger (12) configured to perform heat exchange between the heat transfer fluid and an interior airflow (13) intended to be sent into a vehicle passenger compartment,characterized in that the heat transfer fluid circuit (3) comprises a first branch (14) carrying the second heat exchanger (7) and extending between a divergence point (15) and a convergence point (16), the divergence point (15) being located on the loop (10) between an outlet (17) of the first heat exchanger (5) and the third heat exchanger (12), the convergence point (16) being located on the loop (10) between an inlet (20) of the first heat exchanger (5) and the third heat exchanger (12).

2. Thermal management system (1) according to claim 1, in which the heat transfer fluid circuit (3) comprises a second branch (26) carrying a fourth heat exchanger (29) configured to operate a heat exchange between the heat transfer fluid and a fluid, the second branch (26) extending between a separation point (27) and a junction point (28) disposed on the first branch (14).

3. Thermal management system (1) according to claim 2, wherein the separation point (27) is disposed on the first branch (14) between the convergence point (16) and the second heat exchanger (7), the junction point (28) being disposed on the first branch (14) between the second heat exchanger (7) and the divergence point (15).

4. Thermal management system (1) according to any one of claims 2 or 3, wherein the fluid with which the heat transfer fluid exchanges within the fourth heat exchanger (29) is an airflow external to the passenger compartment of the vehicle or a fluid from a drivetrain of said vehicle.

5. Thermal management system (1) according to any one of claims 1 to 4, wherein the first branch (14) comprises at least one valve (21).

6. Thermal management system (1) according to claim 5, wherein the valve (21) is disposed between the divergence point (15) and an inlet (23) of the second heat exchanger (7) or between the convergence point (16) and an outlet (25) of the second heat exchanger (7).

7. Thermal management system (1) according to any one of claims 1 to 6, wherein the first heat exchanger (5) operates as a condenser, the second heat exchanger (7) operates as an evaporator and the third heat exchanger (12) is a radiator for heating the vehicle's passenger compartment.

8. A method for thermal management of a vehicle, implemented by a thermal management system (1) according to any one of claims 1 to 7, wherein: The refrigerant is circulated in the refrigerant circuit (2), the refrigerant circulating in a loop successively through the compression device (4), the first heat exchanger (5), the expansion device (6), and the second heat exchanger (7), The heat transfer fluid is circulated within the loop (10) of the heat transfer fluid circuit (3), The heat transfer fluid circulating in the loop (10) is separated into two fractions of heat transfer fluid at the point of divergence (15), a first fraction of heat transfer fluid circulating in the loop (10) and passing through the third heat exchanger (12), a second fraction of heat transfer fluid circulating in the first branch (14) and passing through the second heat exchanger (7), The first and second fractions of the heat transfer fluid are mixed at the point of convergence (16).

9. A thermal management method according to claim 8, implemented by a thermal management system (1) according to any one of claims 1 to 9 in combination with claim 2, wherein: The second fraction is separated into two heat transfer fluid flows at the separation point (27), a first heat transfer fluid flow circulating in the first branch (14), a second heat transfer fluid flow circulating in the second branch (26) and passing through the fourth heat exchanger (29), the second flow and the second fraction of heat transfer fluid are mixed at the junction point (28).

10. Thermal management method according to claim 9, implemented when the fourth heat exchanger (29) is inoperative.

11. Thermal management method according to claim 8 or 9, implemented when a representative value of the refrigerant pressure in the second heat exchanger 7 is less than a threshold value.

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