WO2022179917A1

WO2022179917A1 - Method for regulating a refrigerant circuit

Info

Publication number: WO2022179917A1
Application number: PCT/EP2022/053858
Authority: WO
Inventors: Bertrand Nicolas; Mohamed Yahia
Original assignee: Valeo Systemes Thermiques
Priority date: 2021-02-23
Filing date: 2022-02-16
Publication date: 2022-09-01
Also published as: FR3120118A1

Abstract

The present invention relates to a method for regulating a refrigerant circuit (2) comprising a main branch (6), a first branch (7) and a second branch (8), the main branch (6) comprising at least one compression device (27) that is able to be driven in rotation, the first branch (7) comprising a first heat exchanger (11) and a first expansion member (13), the second branch (8) comprising a second heat exchanger (12) and a second expansion member (14), characterized in that: - in a first step, the first expansion member (13) is opened and the speed of rotation of the compression device (27) is increased, and - in a second step, the second expansion member (14) is opened and the speed of rotation of the compression device (27) is increased.

Description

METHOD FOR REGULATING A REFRIGERANT CIRCUIT

The present invention relates to the field of heat treatment systems, and more particularly relates to a method for regulating a refrigerant circuit integrated within such heat treatment systems.

Motor vehicles are commonly equipped with a heat treatment system comprising at least one refrigerant circuit and at least one heat transfer fluid circuit, both used to participate in a heat treatment of different areas or different components of the vehicle. It is in particular known to use the refrigerant circuit and/or the heat transfer fluid circuit to heat treat a flow of air sent into a passenger compartment of the vehicle equipped with such a circuit.

In another application of this circuit, it is known to use the heat transfer fluid circuit to cool electrical or electronic components of the vehicle's traction chain, such as for example an electrical storage device, the latter being used to supply energy to an electric motor capable of setting the vehicle in motion. The heat treatment system thus supplies the energy capable of cooling the electrical storage device during its use in driving phases. Within the heat treatment system, the heat transfer fluid is heat treated by the refrigerant fluid via heat exchange. The heat transfer fluid is then used to cool the electrical or electronic components. An objective of improving such a heat treatment system is to maximize the cooling efficiency of the electrical storage element while promoting overheating of the refrigerant fluid and minimizing the pressure drop. Another objective of improvement is to cool the electrical or electronic storage element as much as possible without harming the comfort of the passenger compartment of the vehicle when the heat treatment of the flow of air sent into the passenger compartment of the vehicle is active. The present invention makes it possible to meet these objectives by proposing a method for regulating a refrigerant circuit, through which a refrigerant fluid passes, for a vehicle comprising a main branch, a first branch and a second branch both in series with the main branch, the main branch comprising at least one refrigerant fluid compression device and a first heat exchanger configured to effect a heat exchange between the refrigerant fluid and a first fluid, the compression device being capable of being driven in rotation up to a maximum rotation threshold speed, the first branch comprising at least a first heat exchanger configured to effect a heat exchange between the refrigerant fluid and a heat transfer fluid flowing through a circuit of heat transfer fluid, the second branch comprising at least a second heat exchanger configured to effect a heat exchange between the coolant fluid and the heat transfer fluid of the heat transfer fluid circuit, the second branch further comprising a coolant accumulation device, the first branch and the second branch being in parallel and s e joining at a first point of convergence arranged downstream of the accumulation device and upstream of the compression device, the first branch and the second branch respectively comprising a first expansion member and a second expansion member respectively arranged upstream of the first heat exchanger and upstream of the second heat exchanger, the refrigerant circuit being configured to lower the temperature of the heat transfer fluid in order to meet a need for cooling an electrical or electronic element heat-treated by the heat transfer fluid circuit, the circuit refrigerant fluid being configured to allow overheating of the refrigerant fluid greater than a minimum overheating threshold, characterized in that during said regulation method:

- in a first step, the first expansion device is opened, advantageously gradually, and the speed of rotation of the compression device is increased as long as the overheating of the refrigerant fluid is greater than the minimum overheating threshold and/or the need for cooling of the electrical or electronic element is not reached,

- in a second step, if the overheating of the refrigerant fluid is less than or equal to the minimum overheating threshold, it opens, advantageously gradually, the second expansion member and the speed of rotation of the compression device is increased as long as the need for cooling of the electrical or electronic element is not reached and the compression device has not reached the speed maximum rotation threshold.

Thanks to such a process, the electrical or electronic element is heat-treated by the heat transfer fluid which itself is cooled by the refrigerant fluid which passes through the first heat exchanger during the first stage, or the first heat exchanger and the second heat exchanger heat in the second step. Such cooling is carried out by minimizing the pressure drop of the refrigerant circuit and without harming the operation of the compression device. The terms "first stage" and "second stage" are only intended to differentiate between the two stages of the regulation process and are not intended to establish a chronological order between the first stage and the second stage, the regulation process can directly launch the second stage without having implemented the first stage before.

Within the refrigerant fluid circuit, the refrigerant fluid is circulated by the compression device. The latter compresses the refrigerant in the vapor state and brings it to high pressure and high temperature. During operation of the compression device, the latter rotates in order to compress the refrigerant fluid. The compression device is capable of increasing the flow rate of refrigerant fluid by increasing its speed of rotation. The compression device has a maximum speed of rotation which may differ depending on the characteristics of said compression device. Once the maximum speed of rotation has been reached, it is no longer possible to increase the flow rate of compressed refrigerant fluid. By maximum threshold speed of rotation, it should be understood that the speed of rotation of the compression device can be capped at a speed lower than the maximum speed of rotation, and this in order to prevent the compression device from rotating at too high a speed. which may, for example, cause noise pollution or vibrations within the vehicle. The first heat exchanger is installed downstream of the compression device and allows at least partial condensation of the refrigerant fluid thanks to the heat exchange performed between the refrigerant fluid and the first fluid. By way of example, the first fluid can be a flow of air outside the vehicle, but it can also be a heat transfer liquid. In order to be able to be arranged across a path of the flow of outside air, the first heat exchanger can for example be installed within a grille located on the front face of the vehicle, where the flow of outside air can s engulf.

Downstream of the first heat exchanger, the first branch and the second branch are both installed in series with the main branch. Depending on the step of the process, the refrigerant fluid can circulate from the main branch to the first branch, or be divided into two fractions, a first fraction of refrigerant fluid circulating in the first branch and a second fraction circulating in the second branch , the first branch and the second branch being in parallel with respect to each other. The first branch and the second branch each comprise, in an order corresponding to the direction of circulation of the refrigerant fluid, an expansion member and a heat exchanger. The first expansion member and the second expansion member make it possible to expand the refrigerant fluid in order to lower its temperature before it passes through the first heat exchanger and the second heat exchanger respectively. Each of the expansion devices can completely close in order to prevent the circulation of the refrigerant fluid in the first branch and in the second branch.

Thus, during the first stage, the first expansion member is progressively opened in order to increase the flow rate of refrigerant fluid circulating in the first branch and therefore in the first heat exchanger. The cooling of the electrical or electronic element is then improved. This opening of the first expansion device is accompanied by the increase in the speed of the compression device within its maximum rotation threshold speed limit so that the compression device can compress all of the refrigerant following the increase in the flow rate of refrigerant fluid circulating in the first branch.

Once expanded, the refrigerant passes through the first heat exchanger, and possibly the second heat exchange if the second step of the process is in progress. The first heat exchanger makes it possible to operate a heat exchange between the low-temperature refrigerant fluid and the heat transfer fluid circulating in the heat transfer fluid circuit. The heat transfer fluid circuit corresponds to a closed loop where the heat transfer fluid is continuously cooled by the refrigerant fluid via the heat exchangers, then cooled the electrical or electronic element requiring heat treatment. The refrigerant fluid, passing through the heat exchangers, therefore participates in the heat treatment of the electrical or electronic element, the latter being likely to release heat during its operation and thus risking rising to a temperature such that its operation may be s find it degraded. The electrical or electronic element therefore acquires a need for cooling which the heat transfer fluid, and therefore indirectly the refrigerant fluid, must meet.

At the outlet respectively from the first heat exchanger and from the second heat exchanger, the first branch and the second branch join together at the first point of convergence, so as to be both connected to the main branch, upstream of the compression device. The second branch has the particularity of comprising the accumulation device, arranged between the second heat exchanger and the convergence point. Any fluid circulating in the second branch therefore passes through the accumulation device.

During the circulation of the refrigerant fluid, the latter is in the vapor state during its compression by the compression device, passes at least partially in liquid form by crossing the first heat exchanger, then passes completely in liquid form during its relaxation by the organs of relaxation. The refrigerant is then evaporated by the heat transfer fluid during the heat exchange occurring within the exchangers thermals. However, it may happen that the refrigerant does not evaporate completely. The accumulation device therefore has the function of retaining a potential fraction of refrigerant fluid maintained in the liquid state before said liquid fraction circulates to the compression device, the latter being able to be damaged in the event of circulation of refrigerant fluid. in liquid form.

The accumulation device is arranged on the second branch. In other words, any fluid passing through the first branch bypasses the accumulation device and flows directly to the compression device. Bypassing the accumulation device is advantageous in that such bypassing makes it possible to reduce the pressure drop of the refrigerant fluid. On the other hand, if a liquid phase bypasses the accumulation device, it circulates through the compression device and risks damaging it.

The regulation method according to the invention is in particular configured so that such a situation does not occur and that the operation of the compression device remains optimal. Thus, superheating of the refrigerant fluid is monitored in order to ensure that the refrigerant fluid is entirely in the vapor state at the outlet of the first heat exchanger.

The minimum overheating threshold corresponds to a minimum temperature limit of the refrigerant fluid where it risks not being completely evaporated. In other words, the minimum overheating threshold is relative to a saturation temperature of the refrigerant fluid, said saturation temperature being specific to the type of refrigerant fluid used. Such a risk of partial evaporation can occur, for example, when the heat transfer fluid has already sufficiently cooled the electrical or electronic element so that the rise in temperature of the heat transfer fluid by cooling the electrical or electronic element weakens. The heat transfer fluid thus evaporates the refrigerant fluid less efficiently within the first heat exchanger.

The risk of partial evaporation at the outlet of the first heat exchanger can therefore occur when the overheating of the refrigerant fluid becomes lower than the minimum overheating threshold. It is from such a situation that the regulation method initiates the second step consisting in progressively opening the second expansion member in order to distribute the refrigerant fluid between the first branch and the second branch. The refrigerant fluid can therefore pass through the accumulation device, which ensures the retention of the liquid phase of the refrigerant fluid. The operation of the compression device is then preserved.

Whether during the first stage or during the second stage, the regulation process is stopped when the compression device reaches its maximum rotation threshold speed or when the need for cooling of the electrical or electronic element is reached.

According to a characteristic of the method, during the first step, the speed of rotation of the compression device as well as a degree of opening of the first expansion member are fixed when the need for cooling is reached. When the need for cooling is reached during the first stage of the regulation process, this means that the electrical or electronic element is sufficiently cooled to operate correctly and that the refrigerant fluid circulating in the first branch is sufficient to thermally regulate the temperature of the electrical or electronic element. In this situation, it is no longer necessary to modify the degree of opening of the first expansion device, nor the speed of rotation of the compression device. These parameters are therefore fixed to prevent a further rise in the temperature of the electrical or electronic element.

According to a characteristic of the method, during the second step, the speed of rotation of the compression device as well as a degree of opening of the first expansion member and of the second expansion member are fixed when the need for cooling is reached. The principle is the same as when the need for cooling is reached during the first stage, except that the degree of opening of the second expansion device is also fixed when the need for cooling is reached during the second stage, being given that the refrigerant circulates in the first branch and in the second branch during the second stage. According to one characteristic of the method, the minimum overheating threshold corresponds to a temperature 5° C. higher than a saturation temperature of the refrigerant fluid. A minimum overheating threshold of 5°C therefore allows the regulation process to move on to the second stage when the overheating of the refrigerant fluid is less than or equal to the minimum overheating threshold without risking partial evaporation at the outlet of the first heat exchanger causing the passage refrigerant fluid in liquid form through the compression device.

According to a characteristic of the method, during the first step, a degree of opening of the first expansion device is fixed when the compression device reaches the maximum rotation threshold speed. The fact that the compression device reaches the maximum rotation threshold speed means that the flow rate of refrigerant fluid circulating in the first branch cannot be increased, the compression device not being able to increase its rotation speed to compress the refrigerant fluid in greater quantity. The degree of opening of the first expansion device is therefore fixed, and the compression device maintains its speed of rotation at the maximum threshold speed.

According to a characteristic of the method, during the second step, a degree of opening of the first expansion member and of the second expansion member is fixed when the compression device reaches the maximum rotation threshold speed. The principle is the same as when the compression device reaches the maximum rotation threshold speed during the first stage, except that the degree of opening of the second expansion device is also fixed when the compression device reaches the threshold speed maximum rotation during the second stage, since the refrigerant circulates in the first branch and in the second branch during the second stage.

According to one characteristic of the method, the refrigerant fluid circulates within a third branch in series with the main branch and in parallel with the first branch and the second branch, the third branch comprising at least one second heat exchanger configured to effecting a heat exchange with an interior air flow sent into a passenger compartment of the vehicle, the third branch further comprising a temperature sensor configured to measure a temperature of the interior air flow at the outlet of the second heat exchanger.

The third branch cools the vehicle interior via the second heat exchanger. The second heat exchanger is disposed at a path of the indoor air flow. The second heat exchanger is configured so that the coolant circulates there at low temperature in order to cool the interior air flow which is subsequently sent to the passenger compartment of the vehicle. As a result, the third branch comprises a third expansion member making it possible to expand the refrigerant fluid, and possibly to regulate the flow rate of the latter. The second heat exchanger can be installed within a ventilation, heating and/or air conditioning installation, which circulates the interior air flow in a cyclic manner in order to cool or heat the passenger compartment according to a mode operation of the heat treatment system.

When the heat treatment system operates according to an operating mode which must ensure the cooling of the passenger compartment of the vehicle, the coolant must then both circulate in the first branch and possibly the second branch in order to cool the electrical or electronic element to heat treated, but also in the third branch to ensure the comfort of the vehicle cabin. The circulation of the refrigerant fluid in the third branch therefore influences the speed of rotation of the compression device and takes priority over the cooling of the electrical or electronic element. The regulation method can therefore be influenced in the event of failure of the refrigerant circuit to cool the passenger compartment of the vehicle to the required temperature, said temperature corresponding to the temperature of the interior air flow at the outlet of the second heat exchanger. The temperature sensor thus makes it possible to control the temperature of the interior air flow and to check whether the latter complies with a temperature requested by a user of the vehicle having activated the air conditioning option for the passenger compartment of the vehicle. According to a characteristic of the method, during the first step, the first expansion device is closed, advantageously gradually, as long as the temperature of the interior air flow measured by the temperature sensor is greater than a comfort threshold temperature. The latter corresponds to the temperature requested for cooling the passenger compartment of the vehicle.

When the temperature of the indoor airflow leaving the second heat exchanger becomes higher than the comfort threshold temperature, it means that the indoor airflow is not cooled enough to meet the comfort demand of the cockpit. The flow rate of refrigerant fluid circulating in the third branch must therefore increase at the expense of the flow rate circulating in the first branch. Gradually closing the first expansion member thus makes it possible to modify the distribution of refrigerant fluid circulating between the first branch and the third branch. The latter is therefore traversed by a greater quantity of refrigerant, and this in order to lower the temperature of the internal air flow at the outlet of the second heat exchanger so that the latter becomes again below the comfort threshold temperature and thus responds correctly to the cooling demand of the passenger compartment of the vehicle.

According to a characteristic of the method, during the second step, the second expansion device is closed, advantageously gradually, as long as the temperature of the interior air flow measured by the temperature sensor is greater than a comfort threshold temperature. The principle is the same as when the temperature of the interior air flow at the outlet of the second heat exchanger becomes higher than the comfort threshold temperature during the first stage. When during the second stage, the refrigerant fluid circulates both within the first branch, the second branch and the third branch and the latter does not allow enough refrigerant fluid to circulate for the flow interior air is sufficiently cooled, it is the second expansion device which is gradually closed in order to increase the flow rate of refrigerant fluid within the third branch and thus improve the cooling of the interior air flow so that its temperature conforms to the comfort threshold temperature. The invention also covers a refrigerant circuit comprising a main branch provided with a compression device and a first heat exchanger, a first branch comprising a first expansion member and a first heat exchanger, a second branch comprising a second expansion member, a second heat exchanger and an accumulation device, said refrigerant circuit implementing a regulation method as described above.

According to one characteristic of the invention, the refrigerant circuit comprises a third branch in series with the main branch and in parallel with the first branch and the second branch, the third branch comprising at least one second heat exchanger configured to operate a heat exchange with an interior air flow sent into the passenger compartment of the vehicle, the second branch and the third branch joining at a second convergence point arranged on the second branch, between the second heat exchanger and the device for accumulation. In other words, the refrigerant circulating in the third branch passes through the accumulation device. Since the internal air flow may not be at a sufficiently high temperature to completely evaporate the refrigerant fluid, the third branch is connected to the second branch so that the liquid fraction of refrigerant fluid coming from the third branch is stopped by the device for accumulation.

According to one characteristic of the invention, the main branch comprises a third heat exchanger arranged between the compression device and the first heat exchanger, the third heat exchanger being configured to perform a heat exchange with a second fluid which may be the interior air flow or a heat transfer liquid. The third heat exchanger makes it possible to ensure the comfort of the passenger compartment of the vehicle in the event of low ambient temperature. The heat exchange is arranged downstream of the compression device and is therefore traversed by the high-temperature refrigerant fluid. The latter is therefore capable of heating the second fluid, for example the flow of interior air which is subsequently sent within the passenger compartment of the vehicle. According to one characteristic of the invention, the main branch comprises an expansion device arranged upstream of the first heat exchanger. The expansion device makes it possible to expand the refrigerant fluid before it passes through the first heat exchanger. Depending on the mode of operation of the refrigerant fluid, the expansion device can expand the refrigerant fluid or allow its passage without expanding it.

Other characteristics and advantages of the invention will become apparent through the description which follows on the one hand, and several embodiments given by way of indication and not limiting with reference to the appended diagrammatic drawings on the other hand, on which :

FIG. 1 represents a heat treatment system provided with a refrigerant circuit capable of implementing a regulation method according to the invention,

Figure 2 is a flowchart for breaking down the different steps of the regulation process,

FIG. 3 represents the circulation of a coolant in the coolant circuit operating according to a cooling mode of a passenger compartment of a vehicle, and during a first step of the regulation method,

FIG. 4 represents the circulation of the coolant in the coolant circuit operating according to the cooling mode of the passenger compartment of the vehicle, and during a second step of the regulation method,

FIG. 5 represents the circulation of the coolant in the coolant circuit operating according to a heating mode of the passenger compartment of the vehicle, and during the first step of the regulation method,

FIG. 6 represents the circulation of the coolant in the coolant circuit operating according to the heating mode of the passenger compartment of the vehicle, and during the second stage of the regulation method.

In Figure 1, a refrigerant circuit is shown in solid lines. In Figures 3 to 6, the portions traversed by the refrigerant are in lines full and the portions without circulation of coolant fluid are in dotted lines. Furthermore, the circulation of the refrigerant fluid is illustrated by indicating its direction of circulation by arrows. The solid lines indicating the circulation of fluid are also of different thickness concerning the refrigerant circuit. More precisely, the thickest solid lines correspond to portions where the refrigerant fluid circulates at high pressure and the thinnest solid lines correspond to portions where the refrigerant fluid circulates at low pressure.

The terms "first", "first", "second", etc. used in the description are not intended to indicate a level of hierarchy or order the elements they accompany. These terms make it possible to distinguish the elements that they accompany and can be interchanged without reducing the scope of the invention.

FIG. 1 represents a refrigerant circuit 2 without indication of fluid circulation. The refrigerant circuit 2 is configured to be part of a heat treatment system î, for example within a vehicle. The refrigerant can for example be a fluid of the Ri34a or Ri234yf type.

The refrigerant circuit 2 comprises in particular a main branch 6 provided with a compression device 27. The compression device 27 makes it possible to circulate the refrigerant fluid and to compress it at very high pressure. Thanks to the compression device 27, the refrigerant fluid can thus circulate in the main branch 6. In order to compress the refrigerant fluid, the compression device 27 is capable of entering into rotation. The higher the speed of rotation of the compression device 27, the greater the flow rate of compressed refrigerant fluid. The compression device 27 can be driven in rotation up to a maximum threshold speed of rotation, which can correspond to the maximum speed of rotation of the compression device 27, or else to a capped rotation speed, lower than the maximum speed of rotation, which constitutes a limit speed before the compression device 27 causes for example noise pollution or vibrations within the vehicle. The main branch 6 comprises a first heat exchanger 21 configured to effect a heat exchange between the refrigerant fluid and a first fluid. As illustrated in Figure 1 and in the following figures, the first fluid is by way of example to a flow of air 4 outside a passenger compartment of the vehicle. The main branch 6 also comprises an expansion device 16 configured to expand the refrigerant fluid before the latter passes through the first heat exchanger 21. The first heat exchanger 21 is arranged downstream of the compression device 27, and the expansion device 16 is arranged upstream of the first heat exchanger 21 and downstream of the compression device 27. The expansion device 16 allows the expansion of the refrigerant fluid after the latter has been placed under high pressure by the compression device 27. The expansion device expansion device 16 nevertheless has the ability to let the coolant pass without expanding it. Thus, the refrigerant fluid can pass through the first heat exchanger 21 at high pressure or at low pressure, the pressure of the refrigerant fluid depending on an operating mode of the refrigerant circuit 2.

Downstream of the first heat exchanger 21, the main branch 6 is divided into a first branch 7, a second branch 8 and a third branch 9, all arranged in series with the main branch 6. The first branch 7, the second branch 8 and the third branch 9 are therefore arranged in parallel with respect to each other. The first branch 7 and the third branch 9 both begin at a first point of divergence 31 where the main branch 6 ends. The second branch 8 begins for its part at a second point of divergence 32 located on the main branch 6, upstream of the first point of divergence 31.

The first branch 7 comprises a first heat exchanger 11 as well as a first expansion member 13 arranged between the first point of divergence 31 and the first heat exchanger 11. The first heat exchanger 11 is configured to effect a heat exchange between the fluid refrigerant circulating in the first branch 7 and a heat transfer fluid circulating within a heat transfer fluid circuit 3. The first expansion member 13 is arranged on the first branch 7, between the first point of divergence 31 and the first heat exchanger 11. The first expansion device 13 makes it possible to expand the refrigerant fluid before the latter passes through the first heat exchanger 11.

The heat transfer fluid circuit 3 is part of the heat treatment system 1, and is intended to heat treat at least one electric or electronic element 25 necessary for the proper operation of the motor vehicle, for example an electric motor or an electric storage element. Such an electric or electronic element 25 is likely to release heat during its operation. The heat transfer fluid therefore has the particular function of cooling the electrical or electronic element 25 in order to preserve the optimal functioning of the latter. The electrical or electronic element 25 therefore has a need for cooling which must be met by the heat transfer fluid, and therefore by analogy the refrigerant fluid. The heat transfer fluid circuit 3 comprises a pump 26 capable of circulating the heat transfer fluid so that the latter passes through the first heat exchanger 11. The low-temperature refrigerant fluid therefore makes it possible to cool the heat transfer fluid during the heat exchange taking place in the first heat exchanger 11. The cooled heat transfer fluid can subsequently cool the electrical or electronic element 25.

Once the heat transfer fluid has captured the calories generated by the electrical or electronic element 25, the heat transfer fluid can again be cooled by the refrigerant fluid by crossing the first heat exchanger 11. The second branch 8 comprises a second heat exchanger 12 and a second expansion device 14 installed between the second point of divergence 32 and the second heat exchanger 12. When the refrigerant fluid is allowed to circulate in the second branch 8, it is expanded by the second expansion device 14, then passes through the second heat exchanger 12. The heat transfer fluid circulating in the heat transfer fluid circuit 3 can therefore be cooled simultaneously thanks to the first heat exchanger 11 and the second heat exchanger 12, thus improving the cooling efficiency of the heat transfer fluid on the electrical or electronic element 25.

The first branch 7 and the second branch 8 join the main branch 6 at a first point of convergence 41, arranged upstream of the compression device 27, within which the refrigerant fluid can again be compressed there. The compression device 27 is only capable of compressing the refrigerant in the vapor state. Thus, it is essential to prevent any non-evaporated refrigerant fluid, that is to say in the liquid state, from passing through the compression device 27 in order to avoid damaging the latter.

To do this, the second branch 8 comprises an accumulation device 17. The latter corresponds to a container making it possible to retain any liquid fraction of the refrigerant fluid so that it does not circulate as far as the compression device 27. The device accumulation 17 is arranged between the second heat exchanger 12 and the first convergence point 41. In other words, the refrigerant fluid circulating in the first branch 7 bypasses the accumulation device 17 while the refrigerant fluid circulating in the second branch 8 passes by the accumulation device

17

Bypassing the accumulation device 17 makes it possible to avoid the loss of charge of the refrigerant fluid. The circulation of the refrigerant fluid via the first branch 7 is therefore favored over the second branch 8. On the other hand, it is essential to ensure that all of the refrigerant fluid passing through the first branch 7, and therefore bypassing the device accumulation 17, is completely evaporated at the outlet of the first heat exchanger 11. To do this, a temperature sensor 18 is arranged at the level of the first heat exchanger 11, and measures the temperature of the refrigerant fluid at the outlet of the first heat exchanger 11, in order to check the condition of said refrigerant. From the reading of the temperature of the refrigerant at the outlet of the first heat exchanger 11, it is possible to deduce therefrom the superheat of the refrigerant. Thus, the temperature sensor 18 is only a non-exhaustive example to determine the superheat of the refrigerant. Depending on the temperature measured by the temperature sensor 18, the circulation of the refrigerant fluid can be modified so that no liquid fraction of refrigerant fluid reaches the compression device 27.

In order to maintain complete evaporation of the refrigerant fluid with certainty when the latter passes through the first heat exchanger 11, the overheating of the refrigerant fluid must remain above a minimum overheating threshold. The minimum overheating threshold therefore corresponds to a temperature or other datum relating to a saturation temperature of the refrigerant fluid.

The third branch 9 begins for its part at the level of the first point of divergence 31, and ends at the level of a second point of convergence 42 arranged on the second branch 8 between the second heat exchanger 12 and the accumulation device 17. The refrigerant fluid circulating in the third branch 9 therefore passes through the storage device 17.

The third branch 9 comprises a third expansion member 15 and a second heat exchanger 22 configured to effect a heat exchange between the refrigerant fluid and an interior air flow 5 intended to be sent to the passenger compartment of the vehicle in order to cool this one. Thus the second heat exchanger 22 is configured to be traversed by the low-temperature refrigerant fluid in order to cool the interior air flow 5. As such, the second heat exchanger 22 can be arranged within a ventilation, heating and/or air conditioning installation, configured to cause the interior air flow 5 to circulate in a closed circuit in order to constantly respond to the cooling of the passenger compartment of the vehicle. The third expansion device 15 makes it possible to expand the refrigerant fluid in order to lower its temperature before passing through the second heat exchanger 22.

The refrigerant fluid circulates in the third branch 9 when the passenger compartment of the vehicle needs to be cooled, for example following a manual command from a user of the vehicle. When the interior cooling function is active, it takes precedence over element cooling. electrical or electronic 25. However, the distribution of refrigerant fluid between the first branch 7, the second branch 8 and the third branch 9 can potentially create a lack of refrigerant fluid circulating in the second heat exchanger 22, leading to insufficient cooling of the indoor airflow 5 versus cooling demand. In order to avoid such a situation, the refrigerant circuit 2 comprises a temperature sensor 19 arranged on the second heat exchanger 22 and making it possible to measure the temperature of the internal air flow 5 at the outlet of the second heat exchanger 22, and this in order to ensure whether the temperature of the interior air flow 5 complies with a comfort threshold temperature determined following the request for cooling of the passenger compartment of the vehicle.

The refrigerant circuit 2 also comprises a third heat exchanger 23, arranged on the main branch 6 downstream of the compression device 27. The third heat exchanger 23 is therefore traversed by the refrigerant at high pressure and at high temperature. , and is configured to effect a heat exchange between the refrigerant fluid and a second fluid. In FIG. 1, as well as in the following figures, the second fluid corresponds to the interior air flow 5. The heat exchange taking place within the third heat exchanger 23 is therefore carried out between the high-temperature refrigerant fluid and the interior air flow 5 in order to heat the latter, which is then sent to the passenger compartment of the vehicle in order to heat the latter. Therefore, the third heat exchanger 23, like the second heat exchanger 22, can be installed within the ventilation, heating and/or air conditioning installation. Depending on the mode of operation of the refrigerant circuit 2, the ventilation, heating and/or air conditioning system may include flaps that can guide the internal air flow 5 so that the latter crosses the relative heat exchanger to the requested mode of operation.

The refrigerant circuit 2 can also comprise a fourth heat exchanger 24 configured to effect a heat exchange between the refrigerant fluid and the outside air flow 4. The fourth heat exchanger 24 is installed on the main branch 6, between the first interchange heat exchanger 21 and the second point of divergence 32. The fourth heat exchanger 24 is therefore installed in series with the first heat exchanger 21, and upstream of the latter with respect to a direction of circulation of the flow of outside air 4 The fourth heat exchanger 24 can thus act as a sub-cooler in order to condense the refrigerant fluid. Sub-cooling the refrigerant fluid allows more effective expansion thereof by the expansion devices 13, 14, 15.

The main branch 6 comprises a third point of divergence 33 between the first heat exchanger 21 and the fourth heat exchanger 24. The refrigerant circuit 2 comprises a fourth branch 51 starting at this third point of divergence 33 and ending at the second point of convergence 42. The fourth branch 51 allows the refrigerant fluid to bypass the heat exchangers 11,12 as well as the second heat exchanger 22, and directly join the accumulation device 17. The fourth branch 51 thus allows a function of heat pump of the refrigerant circuit 2. The fourth branch 51 comprises a first valve 61 authorizing or not the circulation of the refrigerant fluid in the fourth branch 51.

The refrigerant circuit finally comprises a fifth branch 52 starting at a fourth point of divergence 34 located between the third heat exchanger 23 and the expansion device 16, and ending at a third point of convergence 43 located on the main branch 6 between the fourth heat exchanger 24 and the second point of divergence 32. The fifth branch 52 allows the refrigerant fluid to bypass the first heat exchanger 21 and the fourth heat exchanger 24 in order to directly reach the first branch 7 and/or the second branch 8 and/or the third branch 9. The fifth branch 52 comprises a second valve 62 authorizing or not the circulation of the refrigerant fluid in the fifth branch 52. So that the refrigerant fluid circulating in the fifth branch 52 does not circulate towards the fourth heat exchanger 24 once at the third point of convergence 43, the main branch 6 comprises a non-return valve 63 arranged cé downstream of the fourth heat exchanger 24. FIG. 2 is a flowchart diagramming a regulation method 10 implemented within the refrigerant circuit described above. The regulation method 10 makes it possible to respond in an optimal manner to a need for cooling BR of the electrical or electronic element referenced 25 in FIG. 1, while avoiding disturbing certain operations linked to the operation of the refrigerant fluid circuit. During the regulation process 10, a plurality of parameters will therefore be checked regularly, in particular a comparison of a superheat Tl of the refrigerant fluid with respect to the minimum superheat threshold Tsh, the superheat Tl of the refrigerant fluid being relative to the temperature of the fluid refrigerant at the outlet of the first heat exchanger measured by the temperature probe referenced 18 in FIG. of compression reaches the maximum threshold speed of rotation Nmax. Finally, it is checked whether a conditioned air temperature T2 is greater than the comfort threshold temperature Tconf determined by the user of the vehicle. The conditioned air temperature T2 corresponds to the temperature of the interior air flow at the outlet of the second heat exchanger measured by the temperature sensor referenced 19 in FIG. 1. This last check is shown in dotted lines in FIG. 2 because it is only carried out if the refrigerant circuit responds to the mode of cooling of the passenger compartment of the vehicle.

Such verification is therefore optional.

The regulation method 10 therefore begins with an initialization phase 100.

The initialization phase 100 can be automated, for example following detection of too high a temperature of the electrical or electronic element.

The regulation method 10, once the initialization phase has been carried out, first checks whether the overheating T1 of the refrigerant fluid is greater than, less than or equal to the minimum overheating threshold Tsh. If the superheat T1 of the refrigerant fluid is greater than the minimum superheat threshold Tsh, the regulation method 10 continues with a first step 110. If the superheat T1 of the refrigerant fluid is less than or equal to the minimum overheating threshold Tsh, the regulation method 10 continues with a second step 120.

The first step 110 includes in particular a first operation 101 of progressive opening of the first expansion device and of increasing the speed of rotation N of the compression device. When the first expansion device is open, the refrigerant fluid therefore circulates in the first branch and passes through the first heat exchanger in order to cool the heat transfer fluid and therefore meet the need for cooling of the electrical or electronic element. The opening of the first expansion member is accompanied by the increase in the speed of rotation N of the compression device in order to respond to the increase in the flow rate of refrigerant fluid circulating in the refrigerant circuit following the opening of the first organ of relaxation.

Once this first operation 101 has been carried out, the first step 110 continues with a series of checks ensuring that the first operation 101 has not led to any collateral malfunctions within the refrigerant fluid circuit.

Firstly, it is important to ensure that the superheat Tl of the refrigerant fluid is always greater than the minimum superheat threshold Tsh. This verification makes it possible to ensure whether the refrigerant fluid passing through the first heat exchanger is completely evaporated, the first branch bypassing the accumulation device and therefore not tolerating partial evaporation of the refrigerant fluid. The minimum overheating threshold Tsh can for example correspond to a temperature 5°C higher than the saturation temperature of the refrigerant fluid, in order to be certain that evaporation is total.

If the overheating T1 of the refrigerant fluid is less than or equal to the minimum overheating threshold Tsh, then the regulation method 10 continues with the second step 120 which will be described later. If the overheating Tl of the refrigerant fluid is strictly greater than the minimum overheating threshold Tsh, then the first step 110 can continue with the verification of whether or not the cooling requirement BR of the electrical or electronic element has been met.

If the need for cooling BR is reached, then the regulation process 10 is stopped via an end phase 103. Each time the regulation process 10 reaches the end phase 103, the parameters of the refrigerant circuit are then frozen . If the cooling requirement BR is not reached, then the first step continues with the verification of the rotational speed N of the compression device.

If the rotational speed N has reached the maximum rotational threshold speed Nmax, this means that the compression device can no longer tolerate an increase in the flow rate of the refrigerant fluid within the refrigerant circuit. The regulation process 10 therefore transits towards the end phase 103 despite the fact that the need for cooling has not been reached.

If the speed of rotation N is still lower than the maximum threshold speed of rotation Nmax, the regulation method 10 can continue since the speed of rotation N of the compression device can still be increased. At this stage, two alternatives are possible depending on the activity of the vehicle passenger compartment cooling mode.

If the vehicle interior cooling mode is inactive, then the checks are completed, and the first step 110 can continue with a new first operation 101 of progressive opening of the first expansion device and increase in speed. of rotation N of the compression device, then again the application of the aforementioned checks.

If the mode of cooling the passenger compartment of the vehicle is active, then it is also necessary to check whether the opening of the first expansion member has not disturbed the comfort of the passenger compartment of the vehicle. Thus, the conditioned air temperature T2 is compared with the comfort threshold temperature Tconf. If the air conditioning temperature T2 is less than or equal to the comfort threshold temperature, then the demand for comfort in the passenger compartment of the vehicle is satisfied. The checks are therefore complete, and the first step 110 can continue with a new first operation 101 of progressive opening of the first expansion device and increase of the speed of rotation N of the compression device, then again the application of the aforementioned verifications.

If the air conditioning temperature T2 is higher than the comfort threshold temperature Tconf, this means that the comfort request in the passenger compartment of the vehicle is not satisfied. The first step then continues with a first closing phase 104, which consists of a progressive closing of the first expansion device in order to reduce the flow rate of refrigerant fluid circulating in the first branch and therefore to increase the flow rate of refrigerant fluid circulating in the third branch to reduce the temperature of the interior air flow. Once this first closing phase 104 has been carried out, the comparison between the conditioned air temperature T2 and the comfort threshold temperature Tconf is checked again. The first step 110 connects the first closing phases 104 as long as the air conditioning temperature T2 is higher than the comfort threshold temperature Tconf. Once the conditioned air temperature T2 is less than or equal to the comfort threshold temperature Tconf, the first step 110 can continue with a new first operation 101 of progressive opening of the first expansion device and increase of the speed of rotation N of the compression device.

When during the first step 110, the overheating Tl of the refrigerant fluid is less than or equal to the minimum overheating threshold Tsh, this means that there is a risk of partial evaporation within the first branch. In order to avoid this, the regulation method 10 switches to the second step 120 and performs a second operation 102 of progressive opening of the second expansion device and of increasing the speed of rotation N of the compression device. The refrigerant fluid then circulates within the second branch in order to prevent the evaporation of the refrigerant fluid from being incomplete at the level of the first branch.

The second operation 102 is identical to the first operation 101, except that it is the second trigger member which is opened instead of the first trigger member. Thus, the refrigerant passes through the second heat exchanger, which allows the heat transfer fluid to be cooled simultaneously by the first heat exchanger and by the second heat exchanger.

Once the second operation 102 has been performed, the succession of verifications of the second step 120 is substantially similar to the verifications carried out during the first step 110. However, it is not necessary to control the temperature of the refrigerant fluid at the outlet of the second heat exchanger given that the refrigerant fluid circulating in the second branch passes through the accumulation device.

On the other hand, it is always checked if the need for cooling is reached and if the maximum threshold speed of rotation of the compression device is reached. If the need for cooling is reached or if the maximum threshold speed of rotation of the compression device is reached, then the regulation method 10 passes to the end phase 103. If the need for cooling is not reached, if the speed maximum rotation threshold of the compression device is not reached and if the vehicle passenger compartment cooling mode is inactive, then the second operation 102 is repeated.

If the cooling mode is active, then, as for the first step 110, the air conditioning temperature T2 is compared to the comfort threshold temperature Tconf. The difference with the first step 110 lies in the fact that when the conditioned air temperature T2 is higher than the comfort threshold temperature Tconf during the second step 120, then a second closing phase 105 is performed, where it is the second expansion member which is gradually closed and not the first expansion member.

Once this second closing phase 105 has been performed, the comparison between the conditioned air temperature T2 and the comfort threshold temperature Tconf is checked again. The second step 120 connects the second closing phases 105 as long as the conditioned air temperature T2 is higher than the comfort threshold temperature Tconf. Once the conditioned air temperature T2 is less than or equal to the comfort threshold temperature Tconf, the second step 120 can continue with a new second operation 102 of progressive opening of the second expansion member and increase of the speed of rotation N of the compression device.

The regulation process 10 continues in this way until it reaches the end phase 103.

Figures 3 and 4 show the circulation of the refrigerant FR when the refrigerant circuit 2 operates according to the cooling mode of the passenger compartment of the vehicle, respectively during the first step and the second step of the regulation method. In this mode of operation, the events represented in dotted lines on the logic diagram of FIG. 2 are applied. The first valve 61 and the second valve 62 are closed, making the fourth branch 51 and the fifth branch 52 inaccessible.

In FIG. 3, the refrigerant fluid FR is circulated within the main branch 6 and is compressed at high pressure by the compression device 27. The refrigerant fluid FR then passes through the third heat exchanger 23 without influencing the temperature. of the interior air flow 5 thanks to the flaps of the ventilation, heating and/or air conditioning installation mentioned above.

The refrigerant fluid FR then reaches the expansion device 16 which allows the refrigerant fluid FR to pass without expanding the latter. The refrigerant fluid FR continues its circulation in the main branch 6 by crossing the first heat exchanger 21 then the fourth heat exchanger 24 in which the refrigerant fluid FR is cooled and at least partially condensed by the flow of outside air 4.

The refrigerant FR then circulates to the first point of divergence 31 and separates into two fractions. A first fraction circulates within the first branch 7 in order to cool the heat transfer fluid which itself will cool the electrical or electronic element 25, while a second fraction circulates in the third branch 9 in order to cool the interior air flow 5 so that it cools the passenger compartment of the vehicle.

The first fraction of refrigerant FR is therefore expanded by the first expansion member 13 which is at least partially open during the first step of the regulation process, then passes through the first exchanger thermal it. Parallel to this, the pump 26 makes it possible to circulate the heat transfer fluid of the heat transfer fluid circuit 3 so that the heat exchange can be carried out at the level of the first heat exchanger 11. The heat transfer fluid is then cooled, and can then cool the electrical or electronic element 25 before rejoining the pump 26 again. On leaving the first heat exchanger 11, the refrigerant fluid FR then joins the first convergence point 41 bypassing the accumulation device 17 and is again compressed by the compression device 27.

The second fraction of refrigerant fluid FR circulating in the third branch 9 is expanded by the third expansion device 15, then passes through the second heat exchanger 22 in order to cool the interior air flow 5.

At the outlet of the second heat exchanger 22, the refrigerant fluid FR then joins the second branch 8 at the level of the second point of convergence 42, circulates within the accumulation device 17 where a potential liquid fraction of refrigerant fluid FR is retained there, then joins the main branch 6 via the first convergence point 41 before being compressed again by the compression device 27.

In FIG. 4, the circulation of the refrigerant fluid FR is that corresponding to the second step of the regulation process. The circulation of the refrigerant fluid FR is therefore identical except for the fact that the refrigerant fluid FR also circulates in the second branch 8, the second expansion device 14 being open during the second step of the regulation method. Thus, when the refrigerant fluid FR circulates within the main branch 6 as far as the second point of divergence 32, an additional fraction of refrigerant fluid FR circulates in the second branch 8, is expanded by the second expansion device 14 then passes through the second heat exchanger 12 in order to cool the heat transfer fluid within the heat transfer fluid circuit 3, and this in order to improve the cooling of the electrical or electronic element 25.

At the outlet of the second heat exchanger 12, the circulation of the refrigerant fluid FR continues in the second branch 8 as far as the device accumulation 17 where a potential liquid fraction of refrigerant FR is retained there. The refrigerant FR then joins the main branch 6 via the first convergence point 41 before being compressed again by the compression device 27.

FIGS. 5 and 6 represent the circulation of the refrigerant FR when the refrigerant circuit 2 operates according to the heating mode of the passenger compartment of the vehicle, respectively during the first stage and the second stage of the regulation process. In this operating mode, the cooling of the vehicle interior is inactive. The events shown in dotted lines on the flowchart of FIG. 2 are therefore not applied. The first valve 61 and the second valve 62 are open, making the fourth branch 51 and the fifth branch 52 accessible.

In FIG. 5, the refrigerant fluid FR is circulated within the main branch 6 and is compressed at high pressure by the compression device 27. The refrigerant fluid FR then passes through the third heat exchanger 23 at high temperature, allowing thus to heat the interior air flow 5 so that the latter is sent therein into the passenger compartment of the vehicle in order to heat the latter.

The refrigerant fluid FR then reaches the fourth point of divergence 34. The second valve 62 being open, a first fraction of refrigerant fluid FR passes through the fifth branch 52 while a second fraction continues its circulation in the main branch 6.

The first fraction passes through the fifth branch 52 and joins the main branch 6 via the third point of convergence 43 bypassing the first heat exchanger 21 and the fourth heat exchanger 24. The first fraction then circulates to the first point of divergence 31 and circulates exclusively within the first branch 7, access to the third branch 9 being blocked by the third trigger member 15 completely closed.

The first fraction is therefore expanded by the first expansion member 13 which is at least partially open during the first step of the regulation process, then passes through the first heat exchanger 11. Parallel to this, the pump 26 makes it possible to circulate the heat transfer fluid of the heat transfer fluid circuit 3 so that the heat exchange can be operated at the level of the first heat exchanger 11. The heat transfer fluid is then cooled, and can then cool the electrical or electronic element 25 before rejoining the pump 26 again. On leaving the first heat exchanger 11, the refrigerant fluid FR then joins the first convergence point 41 bypassing the accumulation device 17 and is again compressed by the device compression 27.

Concerning the second fraction of refrigerant fluid FR having formed at the level of the fourth point of divergence 34, the latter continues its circulation in the main branch 6, is expanded by the expansion device 16, then passes through the first heat exchanger 21 in which the external air flow 4 is cooled by the expanded refrigerant FR. At the outlet of the first heat exchanger 21, the refrigerant FR reaches the third point of divergence 33. The first valve 61 being open, the refrigerant FR circulates within the fourth branch 51, and directly joins the second point of convergence 42 The refrigerant fluid FR then circulates within the accumulation device 17 where a potential liquid fraction of refrigerant fluid FR is retained there, then joins the main branch 6 via the first convergence point 41 before being compressed again by the compression device 27.

In FIG. 6, the circulation of the refrigerant fluid FR is that corresponding to the second step of the regulation method. The circulation of the refrigerant FR is therefore identical except for the fact that the refrigerant FR also circulates in the second branch 8, the second expansion member 14 being open during the second step of the regulation method. Thus, when the refrigerant fluid FR circulates within the fifth branch 52 then joins the main branch 6 and circulates as far as the second point of divergence 32, an additional fraction of refrigerant fluid FR circulates in the second branch 8, is expanded by the second expansion device 14 then passes through the second heat exchanger 12 in order to cool the heat transfer fluid within the heat transfer fluid circuit 3, and this in order to improve the cooling of the electrical or electronic element 25. At the outlet of the second heat exchanger 12, the circulation of the refrigerant fluid FR continues in the second branch 8 as far as the accumulation device 17 where a potential liquid fraction of refrigerant fluid FR is retained there. The refrigerant FR then joins the main branch 6 via the first convergence point 41 before being compressed again by the compression device 27.

Of course, the invention is not limited to the examples which have just been described and many adjustments can be made to these examples without departing from the scope of the invention. The invention, as it has just been described, achieves the goal it had set itself, and makes it possible to propose a process for thermal regulation of a refrigerant circuit making it possible to optimize the cooling of an electrical or electronic component without causing collateral malfunctions. Variants not described here could be implemented without departing from the context of the invention, provided that, in accordance with the invention, they comprise a regulation method in accordance with the invention.

Claims

CLAIMS l- A method of regulating (io) a refrigerant circuit (2), traversed by a refrigerant fluid (FR), for a vehicle comprising a main branch (6), a first branch (7) and a second branch ( 8) both in series with the main branch (6), the main branch (6) comprising at least one device (27) for compressing the refrigerant fluid (FR) and a first heat exchanger (21) configured to perform an exchange of heat between the refrigerant fluid (FR) and a first fluid, the compression device (27) being capable of being driven in rotation up to a maximum rotation threshold speed (Nmax), the first branch (7) comprising at least a first heat exchanger (11) configured to perform a heat exchange between the refrigerant fluid (FR) and a heat transfer fluid flowing through a heat transfer fluid circuit (3), the second branch (8) comprising at least a second heat exchanger (12 ) configured to operate an exchange e of heat between the refrigerant fluid (FR) and the heat transfer fluid of the heat transfer fluid circuit (3), the second branch (8) further comprising a device (17) for accumulating the refrigerant fluid (FR), the first branch (7) and the second branch (8) being in parallel and joining at a first point of convergence (41) disposed downstream of the accumulation device (17) and upstream of the compression device (27), the first branch (7) and the second branch (8) respectively comprising a first expansion member (13) and a second expansion member (14) respectively arranged upstream of the first heat exchanger (11) and upstream of the second heat exchanger (12) , the coolant circuit (2) being configured to lower the temperature of the heat transfer fluid in order to meet a cooling requirement (BR) of an electrical or electronic element (25) heat treated by the heat transfer fluid circuit (3) , the refrigerant circuit t (2) being configured to authorize overheating (Tl) of the refrigerant fluid (FR) greater than a minimum overheating threshold (Tsh), characterized in that during said regulation process (10):

- in a first step (110), the first expansion member (13) is opened and the speed of rotation (N) of the compression device (27) is increased that the superheat (Tl) of the refrigerant fluid (FR) is greater than the minimum superheat threshold (Tsh) and/or that the cooling requirement (BR) of the electrical or electronic element (25) is not reached,

- in a second step (120), if the overheating (Tl) of the refrigerant fluid (FR) is less than or equal to the minimum overheating threshold (Tsh), the second expansion device (14) is opened and the speed of rotation (N) of the compression device (27) as long as the cooling requirement (BR) of the electrical or electronic element (25) has not been reached and the compression device (27) has not reached the maximum rotation threshold speed (Nmax).

2- Control method (10) according to claim 1, during which, during the first step (110), the speed of rotation (N) of the compression device (27) as well as a degree of opening of the first expansion device (13) are frozen when the cooling requirement (BR) is reached. 3- Regulation method (10) according to claim 1 or 2, during which, during the second step (120), the speed of rotation (N) of the compression device (27) as well as a degree of opening of the first expansion member (13) and of the second expansion member (14) are frozen when the cooling requirement (BR) is reached. 4- Control method (10) according to any one of the preceding claims, during which the minimum overheating threshold (Tsh) corresponds to a temperature 5°C higher than a saturation temperature of the refrigerant fluid.

5- Control method (10) according to any one of the preceding claims, during which, during the first step (110), a degree of opening of the first expansion member (13) is fixed when the compression device (27) reaches the maximum rotation threshold speed (Nmax).

6- control method (10) according to any one of the preceding claims, during which, during the second step (120), a degree of opening of the first expansion member (13) and of the second expansion member ( 14) is frozen when the compression device (27) reaches the maximum rotation threshold speed (Nmax). 7- Control method (10) according to any one of the preceding claims, during which the refrigerant fluid (FR) circulates within a third branch (9) in series with the main branch (6) and in parallel with the first branch (7) and the second branch (8), the third branch (9) comprising at least one second heat exchanger (22) configured to operate a heat exchange with an interior air flow (5) sent in a passenger compartment of the vehicle, the third branch (9) further comprising a temperature sensor (19) configured to detect a temperature of the interior air flow (5) leaving the second heat exchanger (22). 8 Regulation method (10) according to the preceding claim, during which, during the first step (110), the first expansion member (13) is closed as long as the temperature of the interior air flow (5) measured by the temperature sensor (19) is above a comfort threshold temperature (Tconf). 9- Control method (10) according to claim 7 or 8, during which, during the second step (120), the second expansion member (14) is closed as long as the temperature of the interior air flow (5 ) measured by the temperature sensor (19) is greater than a comfort threshold temperature (Tconf). 10- Refrigerant circuit (2) comprising a main branch (6) provided with a compression device (27) and a first heat exchanger (21), a first branch (7) comprising a first expansion member (13) and a first heat exchanger (11), a second branch (8) comprising a second expansion member (14), a second heat exchanger (12) and an accumulation device (17), said refrigerant circuit (2) implementing a control method (10) according to any one of the preceding claims.

11- refrigerant circuit (2) according to the preceding claim, comprising a third branch (9) in series with the main branch (6) and in parallel with the first branch (7) and the second branch (8), the third branch (9) comprising at least one second heat exchanger (22) configured to perform a heat exchange with an air flow interior (5) sent into the passenger compartment of the vehicle, the second branch (8) and the third branch (9) joining at a second convergence point (42) disposed on the second branch (8), between the second heat exchanger (12) and the accumulation device (17). 12- refrigerant circuit (2) according to the preceding claim, wherein the main branch (6) comprises a third heat exchanger (23) disposed between the compression device (27) and the first heat exchanger (21), the third heat exchanger (23) being configured to perform a heat exchange with a second fluid which may be the interior air flow (5) or a heat transfer liquid.

13- refrigerant circuit (2) according to any one of claims 10 to 12, wherein the main branch (6) comprises an expansion device (16) arranged upstream of the first heat exchanger (21).