Method for controlling a refrigerant fluid circuit

Abstract

The invention relates to a method for controlling a refrigerant fluid circuit (1), comprising a first branch (4) provided with a first compression device (9) and a second branch (5) provided with a second compression device (13), the compression devices (9, 13) being able to rotate at variable speeds to comply with a cooling target, characterized in that during the method the rotational speed of the compression devices (9, 13) is increased to a rotational speed corresponding to a determined acoustic threshold as long as the cooling target has not yet been achieved, and, if the cooling target has not yet been achieved, the rotational speeds of the compression devices (9, 13) are converged so that these speeds are identical within + / -10%.

Description

Technical Field

[0001] The field of the invention is that of refrigerant circuits for vehicles, in particular for motor vehicles. The invention more particularly relates to a method for regulating such a refrigerant circuit. Background Art

[0002] Motor vehicles are currently equipped with a refrigerant circuit for heating or cooling different areas or different components of the vehicle. It is particularly known that such a refrigerant circuit is used for thermal treatment of an air flow fed into the interior of a vehicle in which such a circuit is installed.

[0003] Another known application of this circuit is its use in cooling a vehicle's electrical storage device, which is used to power the vehicle's electric motor. Thus, when the electrical storage device is in use during the driving phase, the refrigerant circuit provides the energy needed to cool it. Consequently, the refrigerant circuit is specifically designed to cool the electrical storage device while maintaining a moderate temperature.

[0004] It is also known to charge the vehicle's electrical storage device by connecting it to the household electrical grid for a few hours. This long-term charging technique allows the temperature of the electrical storage device to remain below a certain threshold, which avoids having to use any system to cool the electrical storage device.

[0005] A new charging technology has recently been developed. It involves charging an electrical storage device at high voltage and current, allowing it to be fully charged in a matter of tens of minutes at most. This rapid charging results in heating of the electrical storage device, which must be managed. Furthermore, the possibility that vehicle occupants may remain inside during all or part of this charging time must be considered. During this rapid charging process, the vehicle interior also needs to be thermally managed to maintain acceptable comfort conditions for the passengers, particularly when the vehicle's exterior temperature exceeds 30°C. These two cooling requirements mean that the system must be sized in a way that is difficult to accommodate within the constraints of current motor vehicles, particularly those powered by electric motors.

[0006] The technical problem is therefore to dissipate the thermal energy generated by the electrical storage device, on the one hand, and to cool the vehicle interior, on the other, while limiting the consumption and / or volume and / or noise pollution capacity of a system capable of performing both functions simultaneously. In this context, a known practice is to use a refrigerant circuit for cooling the electrical storage device and the vehicle interior, in particular using two compression devices acting on the refrigerant, the circulation of the refrigerant being distributed between said compression devices so that they do not generate noise pollution due to high levels of activity. However, it is appropriate to ensure that the noise level of one compression device is equal to that of the other. Summary of the Invention

[0007] The present invention solves these various limitations by proposing a method for regulating a refrigerant circuit of a motor vehicle comprising at least a first branch provided with a first heat exchanger configured to thermally treat an electrical storage device of the vehicle and a first compression device associated with the first branch, and a second branch provided with a second heat exchanger configured to thermally treat the interior of the vehicle and a second compression device associated with the second branch, said compression devices being capable of rotating at a variable speed in order to meet a variable objective of cooling the branches, characterized in that during the method:

[0008] - in a step, increasing the rotational speed of at least one compression device to a rotational speed corresponding to a determined acoustic threshold value, as long as the cooling target for the branch to which the compression device is associated has not yet been reached,

[0009] - In a further step, if the cooling target for the branch to which the compression device is associated is not achieved when the rotational speed of the compression device reaches a rotational speed corresponding to a determined acoustic threshold, the rotational speeds of the compression devices are converged until these speeds are identical within + / - 10%.

[0010] The first and second branches of the refrigerant circuit are configured to manage the temperature of the electrical storage device and the temperature of the vehicle interior, respectively. Therefore, the desired temperature of the electrical storage device and / or the vehicle interior depends on the cooling target of the first and / or second branches of the refrigerant circuit, respectively. The cooling target of one or the other branch means that the electrical storage device in the case of the first branch and / or the vehicle interior in the case of the second branch should reach a desired temperature within a given time interval. In this regard, the refrigerant circuit can act on the first and / or second branches to cool the electrical storage device and / or the vehicle interior.

[0011] The cooling of the first branch and / or the second branch is at least partially dependent on the rotational speed of the first compression device and the second compression device, respectively. Thus, to meet a cooling target for each of these compression devices associated with the branch, these devices rotate at a given rotational speed. As long as the cooling target is not met, the compression devices rotate at increasing rotational speeds in order to compress a greater amount of refrigerant in the branch associated with the rotating compression device.

[0012] The compression device can rotate up to a rotational speed corresponding to a determined acoustic threshold. The acoustic threshold has been determined as the noise limit of the compression device before the compression device generates noise pollution inside or around the vehicle. In other words, although the compression device can rotate at a higher rotational speed than the rotational speed corresponding to the determined acoustic threshold, the refrigerant circuit control method intentionally limits the rotational speed of the compression device so that the compression device does not cause noise pollution.

[0013] However, despite the fact that the rotational speed of the compression device corresponds to a determined acoustic threshold, the branch to which the compression device is associated may not achieve its cooling target. To achieve this goal, and in the case that the rotational speed of the compression device does not exceed the rotational speed corresponding to the determined acoustic threshold, the regulation method will cause the rotational speeds of the compression devices to converge with each other so that they become identical or substantially identical to each other within plus or minus 10%. In other words, the rotational speeds of the compression devices that have hitherto been unaffected by the implementation of this method will be increased to allow a greater amount of refrigerant to be compressed. The additional contribution of the compression device in terms of refrigerant compression allows the associated branch to achieve its cooling target. The fact that the compression devices rotate at the same rotational speed means that the amount of noise from one compression device can be balanced with the amount of noise from another compression device without exceeding the acoustic threshold, while providing the required cooling of the electrical storage device and / or the vehicle interior.

[0014] This approach therefore makes it possible to reduce noise pollution by operating both compression devices at speeds below an acceptable acoustic threshold, whereas a single compression device would not do so, which would impose a very high rotational speed and thus be noisy for the passengers remaining in the vehicle.

[0015] The refrigerant circuit is a closed circuit. The refrigerant circuit may, for example, comprise a main branch of the circuit, which extends to a bifurcation point where the circuit splits into two parts, forming a first branch and a second branch arranged parallel to each other. The first branch and the second branch extend to a convergence point connecting these branches so as to reform the main branch. The main branch comprises a main heat exchanger which can be mounted at the front of the vehicle. Thus, the main heat exchanger can be used as a condenser or an evaporator. The refrigerant is, for example, a subcritical fluid, such as those known by the references R134A or 1234YF. Alternatively, the fluid may be a natural fluid, such as carbon dioxide, which has the reference R744.

[0016] The first branch, more specifically the first heat exchanger, is configured to thermally manage the vehicle's electrical storage device. It is therefore dedicated exclusively to this electrical storage device and, in a particular embodiment, does not have the function of cooling any other components. The first heat exchanger exchanges thermal energy directly between the refrigerant and the vehicle's electrical storage device, i.e. by convection or conduction between the first heat exchanger and the electrical storage device, or indirectly by a heat transfer fluid circuit, which is used to transfer thermal energy from the electrical storage device to the first heat exchanger. It will therefore be understood that the cooling of the electrical storage device may be indirect. Alternatively, the first heat exchanger may be in contact with the electrical storage device. In this case, the cooling of the electrical storage device is direct.

[0017] The second branch, more particularly the second heat exchanger, is designed to pass the interior air flow sent into the interior of the motor vehicle through it. In this case, the second heat exchanger can be incorporated into an external system, such as a heating, ventilation and / or air conditioning system.

[0018] Compression devices are located on the first and second branches, one for each branch. Each compression device is located downstream of the heat exchanger relative to the refrigerant flow direction in the associated branch. The compression devices are, for example, electric compressors, such as variable-speed, fixed-displacement compressors. This allows for control of the thermal output of the refrigerant circuit. Each compression device is independent of the others, meaning one can be active while the other is inactive, or they can operate simultaneously at different speeds.

[0019] According to one feature of the method, during the method, whether the cooling target of the branch associated with the compression device has been achieved is determined by comparing the cooling capacity of the branch with the cooling target of the branch associated with the compression device. When the first and / or second compression device rotates at a given rotational speed, this results in a cooling capacity that is significantly higher than the amount of refrigerant compressed by the compression device. Therefore, the cooling capacity of the branch depends at least in part, and particularly substantially, on the rotational speed of the compression device associated with the branch. In other words, the cooling capacity of the branch and the rotational speed of the compression device associated with the branch are proportional to each other. Therefore, the higher the rotational speed of the compression device, the higher the cooling capacity of the branch including the compression device. During the method, the cooling capacity of the branch is compared with the cooling target of the same branch associated with the compression device. When the cooling capacity is greater than or equal to the cooling target, the method stops, indicating that the cooling target has been achieved. As long as the cooling capacity is below the cooling target, the cooling target is not achieved. Therefore, as the method continues, the rotational speed of the compression device increases. If the cooling capacity is still below the cooling target when the compression device associated with the branch reaches a rotational speed corresponding to a predetermined acoustic threshold, the rotational speeds of the compression devices converge.

[0020] According to another feature of the method, the rotational speed corresponding to the determined acoustic threshold for one of the compression devices is lower than the maximum rotational speed of one or both compression devices. The maximum rotational speed of a compression device allows the generation of refrigeration capacity in the branch comprising said compression device, but the amount of noise generated is considered unacceptable. Therefore, during the method according to the invention, the compression device does not reach this maximum rotational speed, said compression device being limited to a rotational speed corresponding to the determined acoustic threshold. By way of example, the maximum rotational speed may be 9,000 revolutions per minute, while the rotational speed corresponding to the determined acoustic threshold may be 5,000 revolutions per minute. It must be noted that each compression device has its own maximum rotational speed and its own rotational speed corresponding to the determined acoustic threshold. Such speed may depend, for example, on the model of compression device used. Assuming that the compression devices of the refrigerant circuit are identical, the maximum rotational speed and the rotational speed corresponding to the determined acoustic threshold are identical or substantially identical to one another.

[0021] According to one feature of the method, a refrigerant circuit is capable of allowing refrigerant to flow from a first branch to a second branch, the refrigerant circuit comprising a pipe providing a connection between the first branch and the second branch, the pipe being provided with a control device capable of regulating the passage of refrigerant from one branch to the other. Advantageously, at least one pipe connects a portion of the first branch located between the first heat exchanger and the first compression device to a portion of the second branch located between the second heat exchanger and the second compression device. Such a pipe allows refrigerant to flow from one branch to the other. The pipe comprises at least one device for controlling the flow of refrigerant within the pipe, so as to allow the flow rate of the refrigerant circulating within the pipe to be regulated. Thus, the pipe and the control device are capable of distributing the refrigerant between each branch according to the rotational speed of the compression device.

[0022] According to one feature of this method, when the first compression device reaches a rotational speed corresponding to a predetermined acoustic threshold, the control device allows refrigerant to flow through the pipe without necessarily meeting the first cooling target of the first branch, and the second compression device is either inoperative or rotates at a speed below the rotational speed corresponding to the predetermined acoustic threshold. If the cooling capacity generated by the first branch still falls short of the first branch's cooling target when the first compression device reaches the rotational speed corresponding to the predetermined acoustic threshold, the second compression device will also rotate to compress some refrigerant. To meet this requirement, the second branch, including the second compression device, needs to receive refrigerant. This is achieved by a pipe connecting the two branches and a control device that can be opened to allow refrigerant exiting the first heat exchanger to flow from the first branch to the second branch. Thus, both compression devices are supplied with refrigerant, increasing the amount of compressed refrigerant compared to a case where only one compression device is operating. This situation is also effective when the second compression device reaches a rotational speed corresponding to the predetermined acoustic threshold but fails to meet the second branch's cooling target, such as during accelerated cooling of the vehicle interior after severe warm-up conditions. Therefore, the first compression device assists the second compression device, and the first branch can receive an inflow of refrigerant, for example, via the pipe.

[0023] According to a feature of the method, the first compression device and the second compression device converge to a rotational speed lower than the rotational speed corresponding to the determined acoustic threshold, a first rotational speed of the first compression device being reduced and a second rotational speed of the second compression device being increased.

[0024] According to a feature of the method, after the rotational speeds have converged, the sum of the rotational speeds of each compression device is greater than the rotational speed corresponding to the determined acoustic threshold. When the first or second compression device reaches its rotational speed corresponding to the determined acoustic threshold without reaching the cooling target of its particular branch, this means that the rotational speed of the compression device is insufficient to produce a refrigeration capacity that can meet the cooling target. Therefore, when the rotational speeds of the two compression devices converge with each other, the refrigeration capacity of the associated branch is the result of the two compression devices. Since a single compression device associated with the branch and rotating at a rotational speed corresponding to the determined acoustic threshold cannot reach the cooling target of the branch, the present invention allows the sum of the two rotational speeds of the two compression devices to be greater than the rotational speed corresponding to the determined acoustic threshold, so that the cooling target can be reached as long as each speed of the compression device is below the determined acoustic threshold.

[0025] According to one feature of the method, as long as the first cooling target for the first branch has not been achieved, after the speeds have converged, the respective speeds of each compression device are increased in coordination with one another until a speed corresponding to a determined acoustic threshold. It is possible that, despite both compression devices contributing, the first cooling target may still not be achieved, even if the sum of the speeds of the compression devices is greater than the speed corresponding to the determined acoustic threshold. In this case, the speeds of the compression devices are increased equally and simultaneously to enable the first cooling target to be met while maintaining the speeds equal or substantially equal. This increase in speed may continue until both compression devices reach a speed corresponding to the determined acoustic threshold.

[0026] According to another feature of the method, the control device regulates the flow of refrigerant through the pipe based on a variable opening cross section. In other words, the control device is capable of controlling the refrigerant flow rate through the pipe connecting the first branch and the second branch. Thus, the volume of refrigerant flowing from one branch to the other can be adjusted, and this regulation can be performed based on the rotational speed of the compression device. The opening cross section of the control device allows a predetermined flow rate of refrigerant flowing through the pipe to be defined.

[0027] According to one feature of the method, when the first compression device reaches a rotational speed corresponding to a determined acoustic threshold without achieving a first cooling target for the first branch, and as long as the second compression device rotates at a speed below the rotational speed corresponding to the determined acoustic threshold, the control device increases the opening cross section. In this case, the second compression device assists the first compression device in order to achieve the first cooling target. In this case, the control device increases its opening cross section to supply a larger amount of refrigerant to the second compression device.

[0028] According to one feature of the method, the refrigerant flow in the first branch is regulated by a first expansion member located upstream of the first heat exchanger. The first expansion member may be an electrically controlled expansion member. Thus, the first expansion member is electrically or electronically operated. The first expansion member allows for regulation of the refrigerant flow in the first branch. Like the control device, the first expansion member has a variable opening, thereby enabling regulation of the refrigerant flow in the first branch and, consequently, of the refrigerant flow through the first heat exchanger, the function of which is to cool the electrical storage device.

[0029] According to one feature of the method, the refrigerant flow rate in the second branch is regulated by a second expansion member of the second heat exchanger. Like the first expansion member, the second expansion member can be an electrically controlled expansion member, thus being electrically or electronically operated. The second expansion member allows for regulation of the refrigerant flow rate in the second branch. The second expansion member also has a variable opening, thereby regulating the refrigerant flow rate in the second branch and, consequently, the refrigerant flow rate through the second heat exchanger, whose function is to cool the vehicle interior.

[0030] The invention also covers a thermal management system comprising a refrigerant circuit implementing the regulation method described above.

[0031] According to a feature of the invention, the thermal management system includes a control module configured to manage the implementation of a regulation method. The method for regulating the refrigerant circuit can be controlled by a control module forming part of the thermal management system. The control module can, for example, receive a signal indicating that an electrical storage device of the vehicle is at an excessively high temperature and / or a signal indicating that the vehicle interior requires cooling in response to a command given by a vehicle occupant. In response to the commands contained in these signals, the control module controls elements of the refrigerant circuit to allow cooling of the electrical storage device and / or the vehicle interior. In this way, the control module can control the rotational speed of the compression device and the opening of the expansion member of the duct control device and the branch. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Other features and advantages of the invention will become more apparent from the following description and also from a number of exemplary embodiments given in a non-limiting manner with reference to the accompanying schematic drawings, in which:

[0033] Figure 1 is a schematic diagram of a refrigerant circuit using the regulation method according to the present invention,

[0034] Figure 2 is a schematic diagram of the circulation of a refrigerant in a circuit according to a first example, in which only the electrical storage device needs to be cooled,

[0035] Figure 3 is a curve of the variation of the rotation speed of the compression device over time, and a curve of the evolution of the refrigeration capacity in one branch of the refrigerant circuit relative to the cooling target, said curves representing the first example explained above,

[0036] Figure 4 is a schematic diagram of refrigerant circulating in a circuit according to a second example, in which the electric storage device and the interior of the vehicle need to be cooled, with priority given to cooling the electric storage device.

[0037] Figure 5 are curves showing the variation of the rotation speed of the compression device over time, as well as the variation of the refrigeration capacity of the first branch of the refrigerant circuit relative to its cooling target, and the variation of the opening cross sections of the two expansion components and the control device of the refrigerant circuit, said curves representing the second example described above,

[0038] Figure 6 is a schematic diagram of the refrigerant circulating in a circuit according to a third example, in which the electric storage device and the interior of the vehicle require cooling without particular priority,

[0039] Figure 7 are time-varying curves of the rotation speed of the compression device, the refrigeration capacities of the two branches of the refrigerant circuit relative to their cooling targets, and the opening cross section of the control device of the refrigerant circuit, which curves represent the third example described above. DETAILED DESCRIPTION

[0040] With respect to the figures depicting refrigerant circuits, the terms upstream and downstream used in the following description refer to the direction of flow of the relevant fluid, namely, the refrigerant. The refrigerant is represented by arrows, which indicate the direction of flow of the refrigerant through the pipes. Solid lines indicate portions of the circuit through which the refrigerant flows. Short dashed lines indicate no refrigerant flow, while long dashed lines indicate that refrigerant flow is possible under certain conditions, which will be explained later in the description.

[0041] therefore, Figure 1 A thermal management system 100 is shown comprising a circuit 1 in which a refrigerant circulates. The circuit 1 comprises a main branch 2, a first branch 4 and a second branch 5 connected in series with the main branch 2 so as to form a closed circuit in which a thermodynamic cycle takes place.

[0042] The first branch 4 and the second branch 5 separate at a diverging point 6 and come back together again at a converging point 7. Between these two points, the first branch 4 and the second branch 5 are arranged parallel with respect to each other.

[0043] The main branch 2 extends from a convergence point 7 to a divergence point 6 and includes a main heat exchanger 3. This latter is intended to allow the passage of refrigerant and external air. This main heat exchanger 3 is the site of the exchange of thermal energy between the refrigerant and the external air. This main heat exchanger 3 can be installed at the front of a vehicle equipped with the circuit 1 according to the present invention, in which case the air flows from the vehicle interior to the exterior through it.

[0044] The first branch 4 starts at a diverging point 6 and ends at a converging point 7, and includes, in order along the flow direction of the refrigerant in the first branch 4, a first expansion member 8, a first heat exchanger 10, and a first compression device 9 for compressing the refrigerant. Therefore, the first heat exchanger 10 is interposed between the outlet 29 of the first expansion member 8 and the inlet 30 of the first compression device 9.

[0045] This first heat exchanger 10 is specifically dedicated to the thermal management of an electrical storage device 11, the function of which is to supply electrical energy to one or more electric motors used to propel the vehicle. This electrical storage device accumulates or releases this electrical energy in order to propel the motor vehicle via the dedicated electric motors. For example, it can be a battery pack consisting of a plurality of cells that store electrical current.

[0046] The first heat exchanger 10 exchanges heat energy directly with the electrical storage device 11 by convection or conduction. This is referred to as direct thermal management of the electrical storage device 11.

[0047] In another alternative, the first heat exchanger 10 is thermally associated with the electrical storage device 11 via a heat transfer fluid circuit. This is known as indirect thermal management of the electrical storage device 11. The heat transfer fluid collects thermal energy from the electrical storage device 11 and transports it to the first heat exchanger 10.

[0048] The first expansion member 8 influences the thermal power used by the first heat exchanger 10 by being able to change the thermal power from the maximum power of the first heat exchanger 10 to any thermal power below the maximum power, in particular by reducing the passage cross section of the refrigerant in the first expansion member 8. The first expansion member 8 is a thermal expansion valve, an electronic expansion valve, a throttle tube, etc.

[0049] The inlet 30 of the first compression device 9 is connected to the outlet 32 ​​of the first heat exchanger 10 , and the outlet 31 is connected to the convergence point 7 .

[0050] The first branch 4 of the circuit 1 also comprises a portion 33 extending between the first heat exchanger 10 (more specifically its outlet 32 ​​) and the first compression device 9 (especially its inlet 30 ).

[0051] The second branch 5 begins at a diverging point 6 and ends at a converging point 7. It includes, in order, a second expansion member 12, a second heat exchanger 14, a refrigerant accumulation device 36, and a second compression device 13 for compressing the refrigerant, in the direction of refrigerant flow in the second branch 5. Therefore, the second heat exchanger 14 and the accumulation device 36 are interposed between the outlet 34 of the second expansion member 12 and the inlet 35 of the second compression device 13. From the perspective of the refrigerant, the second heat exchanger 14 is located upstream of the accumulation device 36. The accumulation device 36 can take the form of an accumulator in which the liquid phase contained in the refrigerant accumulates, and the gaseous phase of the same refrigerant is extracted by the second compression device 13. Alternatively, the accumulation device 36 can be a drying tank, which can be advantageously incorporated into the main heat exchanger 3.

[0052] The second heat exchanger 10 is configured to heat-treat the flow of interior air being fed into the vehicle interior. The second heat exchanger 14 can be installed in a heating, ventilation and / or air-conditioning device cooperating with the circuit 1 to form a thermal regulation system for a motor vehicle. This second heat exchanger 14 can thus act as an evaporator to cool the flow of interior air being fed into the vehicle interior.

[0053] The second expansion member 12 acts on the thermal power used by the second heat exchanger 14, which can vary this thermal power in order to achieve more or less cooling of the interior air flow fed into the vehicle interior. The second expansion member 12 is a thermostatic expansion valve, an electronic expansion valve, a throttle tube or the like.

[0054] The inlet 35 of the second compression device 13 is connected to the outlet 37 of the accumulation device 36 , the outlet 38 of which is connected to the convergence point 7 .

[0055] The second branch 5 of the circuit 1 also comprises a portion 39 extending between the second heat exchanger 14 (more specifically its outlet 40) and the second compression device 13 (especially its inlet 35). The accumulation device 36 may be located in this portion 39 of the second branch 5.

[0056] According to one aspect of the invention, circuit 1 comprises at least one duct 15 fluidically connecting portion 33 of first branch 4 to portion 39 of second branch 5. Such duct 15 allows first branch 4 and second branch 5 to communicate, thus offering the possibility of sharing both compression devices 9, 13.

[0057] The duct 15 is thus connected to a first point 41 situated in the portion 33 of the first branch 4 and to a second point 42 situated in the portion 39 of the second branch 5 .

[0058] The circulation of the refrigerant in the pipe 15 can be controlled. Therefore, the pipe 15 can include a control device 16 for controlling the circulation of the refrigerant in the pipe 15. The control device 16 can include or consist of an expansion device 17, the function of which is to close the pipe 15 or at least partially open the pipe 15, or to achieve a pressure drop to cause the refrigerant to expand.

[0059] In summary, the control means 16 for controlling the circulation of the refrigerant FR in the pipe 15 may comprise a first non-return valve 18. The latter thus allows the refrigerant to circulate from the portion 33 of the first branch 4 to the portion 39 of the second branch 5 and prevents this reverse circulation, i.e. from the portion 39 of the second branch 5 to the portion 33 of the first branch 4.

[0060] From the refrigerant point of view, the circuit 1 according to the invention may also comprise a first conduit 19 extending parallel to the conduit 15. Thus, the first conduit 19 extends from the portion 39 of the second branch 5 to the portion 33 of the first branch 4. The first conduit 19 extends between a third point 43 situated in the portion 39 of the second branch 5 and the first point 41.

[0061] The first conduit 19 may include a second non-return valve 20. The latter thus allows the refrigerant to circulate from the portion 39 of the second branch 5 to the portion 33 of the first branch 4 and prevents the reverse circulation, ie from the portion 33 of the first branch 4 to the portion 39 of the second branch 5.

[0062] Thermal management system 100 further comprises a control module 50 configured to act on circuit 1, more specifically, on compression devices 9 and 13, expansion members 8 and 12, and control device 16. Control module 50 is thus able to modify the rotational speed of compression devices 9 and 13. Control module 50 can also act on expansion members 8 and 12, more specifically on the degree of their opening, which serves to control the flow rate of the refrigerant circulating in first branch 4 and second branch 5, respectively. Finally, control module 50 can influence the amount of refrigerant circulating in pipe 15 by adjusting the degree of opening of control device 16.

[0063] The control module 50 is an electronic unit that may form part of a thermal management system 100 comprising the circuit 1 forming the subject of the present invention. Certain steps of the method may be implemented by the control module 50.

[0064] The actions of control module 50 can, for example, depend on a signal received by it. This signal can be used, for example, to indicate to control module 50 that electrical storage device 11 is at an excessively high temperature, such as after being recharged in rapid charging mode. The signal can also indicate that the vehicle interior requires cooling, as requested by one of the vehicle's occupants. Based on the received signal, control module 50 acts on or off one or more components, including compression devices 9, 13, expansion members 8, 12, and / or control device 16, particularly expansion device 17. The signal also indicates a state of electrical storage device 11 and / or the vehicle interior, which control module 50 analyzes to determine cooling targets for first branch 4 and / or second branch 5, respectively. Various examples are described below.

[0065] Figure 2 FIG. 1 shows a circuit 1 and the circulation of the refrigerant FR in the circuit according to a first example. Figure 2 In this first example, only the electrical storage device 11 requires cooling. Therefore, refrigerant FR circulates through the main branch 2 and the first branch 4. Because the vehicle interior does not require cooling, the flow of refrigerant FR through the second branch 5, more specifically between the second expansion member 12 and the first point 41, and between the second expansion member 12 and the second point 42, is interrupted. In particular, the second expansion member 12 is closed. According to this first example, the control device 16 is fully opened. Therefore, refrigerant FR can flow between the first branch 4 and the second branch 5, more specifically, between the portion 33 of the first branch 4 and the portion 39 of the second branch 5.

[0066] So far, only the electrical storage device 11 needs to be cooled, the first compression device 9 being active or predominantly active compared to the second compression device 13. Details regarding the rotational speed of each compression device will be explained later.

[0067] Figure 3 1 and 2 are curves showing changes in the rotation speed of the compression device over time, and a curve showing changes in the refrigeration capacity in one branch of the refrigerant circuit relative to the cooling target, which curves represent the first example explained above. Figure 3The top curve shows the variation of the compression device rotational speed over time. The rotational speed of the compression device can be measured, for example, in revolutions per minute. The compression device can rotate at a maximum rotational speed 63, which is the same for both compression devices, for example. The maximum rotational speed 63 may correspond, for example, to 9,000 revolutions per minute. However, during the method according to the present invention, the compression device does not reach the maximum rotational speed 63, as such a speed would generate undesirable noise pollution. Therefore, the compression devices are limited to a rotational speed corresponding to a specific acoustic threshold 60. Each compression device has its own rotational speed corresponding to the specific acoustic threshold 60, which may vary, for example, depending on the type of compression device used. In this case, the rotational speed corresponding to the specific acoustic threshold 60 is the same for both compression devices. It is taken into account that rotational speeds above the rotational speed corresponding to the specific acoustic threshold 60 may generate noise pollution. Therefore, the compression devices are not rotated beyond the rotational speed corresponding to the specific acoustic threshold 60, for example, 5,000 revolutions per minute.

[0068] Figure 3 The bottom curve shows the variation of the first cooling capacity 73 over time, which should achieve the first cooling target 71. The first cooling capacity 73 and the first cooling target 71 are related to the first branch. The first cooling capacity 73 and the first cooling target 71 are expressed in the same units. For example, one can reason based on thermodynamic cooling units, such as Figure 3 As shown, or reasoning is performed based on the temperature in degrees Celsius. A first cooling target 71 is associated with the first branch, which itself is configured to cool the electrical storage device using the first heat exchanger. First cooling target 71 is required to meet the electrical storage device cooling requirement requested by the control module, for example, after an excessively high temperature has been measured. In this case, the goal of the first branch is to generate a first cooling capacity 73 that meets first cooling target 71.

[0069] To meet the first cooling target 71, the method begins by rotating the first compression device at the first rotational speed 61. As a result, the first cooling capacity 73 of the first branch increases and gradually approaches the first cooling target 71 because the first rotational speed 61 of the first compression device gradually increases, and because the first cooling capacity 73 of the first branch depends in part on the first rotational speed 61 of the first compression device.

[0070] Meanwhile, assuming that the vehicle interior does not need to be cooled, the second rotating device does not operate, and therefore its rotation speed corresponds to the second rotation speed 62 of zero.

[0071] The first rotational speed 61 increases over time until a first time t91. At the first time t91, the first compression device reaches the first rotational speed 61, which is equal to the rotational speed corresponding to the determined acoustic threshold 60 and, according to the method, is therefore unable to rotate at a higher rotational speed. It will be noted that at the first time t91, the first cooling capacity 73 has not yet reached the first cooling target 71.

[0072] To ensure that first cooling capacity 73 reaches cooling target 71 without exceeding first rotational speed 61 at the determined acoustic threshold 60, the method requires the previously inactive second compression device to contribute. Consequently, the rotational speeds of the compression devices converge. Therefore, after the second compression device begins operating, first rotational speed 61 decreases, while second rotational speed 62 increases. Consequently, the compression devices rotate at the same rotational speed, or substantially the same speed within ±10%, as each other. This rotational speed may be, for example, 3,000 revolutions per minute. While this speed is lower than the speed corresponding to the determined acoustic threshold 60, the sum of the rotational speeds of the compression devices is considered here, resulting in a higher total rotational speed than would be achieved by a single compression device rotating at the speed corresponding to the determined acoustic threshold 60.

[0073] The combination of the two compression devices rotating at substantially the same rotational speeds as each other then allows the first refrigeration capacity 73 to meet the requirements of the first cooling target 71. Since the control device is open, the second compression device receives refrigerant because the refrigerant passes through the pipe connecting the two branches and is therefore able to compress the refrigerant like the first compression device. Figure 3 As shown, the rotational speeds of the compression devices can also be increased in a coordinated manner with one another up to a rotational speed corresponding to a determined acoustic threshold 60 of at least one compression device, thereby ensuring that the first cooling target 71 is met.

[0074] pass Figure 2 and 3 The first example explained corresponds to the case where only the electric storage device needs to be cooled, but such an example is also effective when only the vehicle interior needs to be cooled, and the circuit can circulate the refrigerant through the second branch.

[0075] Figure 4 FIG. 1 shows a circuit 1 and the circulation of the refrigerant FR in the circuit according to a second example. Figure 4In this second example, the electrical storage device 11 and the vehicle interior require cooling, but cooling the electrical storage device 11 takes priority. Therefore, refrigerant FR circulates throughout the main branch 3 and the first branch 4. As long as the electrical storage device 11 is not adequately cooled, the flow of refrigerant FR in the second branch 5, more specifically between the second expansion member 12 and the first point 41 and between the second expansion member 12 and the second point 42, is interrupted. According to this second example, the control device 16 is fully open. Consequently, the refrigerant FR can flow between the first branch 4 and the second branch 5, more specifically between the portion 33 of the first branch 4 and the portion 39 of the second branch 5. Still according to this second example, the first expansion member 8 is opened, allowing the refrigerant FR to flow through the first branch 4, thereby cooling the electrical storage device 11. As long as the electrical storage device 11 is not adequately cooled, the second expansion member 12 is closed. Once this objective is achieved, the second expansion member 12 opens, allowing the refrigerant FR to flow through the second branch 5, thereby cooling the vehicle interior. The compression devices 9 and 13 rotate at a constant rotational speed corresponding to a predetermined acoustic threshold.

[0076] Figure 5 The curves showing the change in the rotation speed of the compression device over time, the change in the refrigeration capacity of the first branch of the refrigerant circuit relative to its cooling target, and the change in the opening cross-section of the two expansion components and the control device of the refrigerant circuit are shown, which represent the second example described above.

[0077] Figure 5 The top curve represents a first rotational speed 61 of the first compression device and a second rotational speed 62 of the second compression device, for example in revolutions per minute.According to a second example, the compression devices rotate constantly over time at a rotational speed corresponding to a determined acoustic threshold 60 of at least one compression device.

[0078] Figure 5 The middle curve in FIG represents the time variation of the first cooling capacity 73. As before, the first cooling capacity 73 needs to meet the first cooling target 71 to solve the cooling demand of the electric storage device.

[0079] Figure 5The curve at the bottom shows the change over time of the opening cross-sections of the two expansion members and the control device, in particular the expansion device. Each opening cross-section can be expressed, for example, as a percentage, with 0% representing a completely closed cross-section and 100% representing a completely open cross-section. According to a second example, the first expansion member has a first opening cross-section 81 that is at least partially open. The first expansion member allows the refrigerant to circulate in the first branch, thereby cooling the electrical storage device. Because the cooling of the electrical storage device is given priority, the second opening cross-section 82 of the second expansion member is initially closed. Therefore, the second branch cannot cool the vehicle interior. Finally, the control device is also partially open to a third opening cross-section 83, which enables each compression device to receive refrigerant and be able to compress the refrigerant.

[0080] In this case of the method, the compression devices initially rotate at the same rotational speed as one another or at a rotational speed substantially equal to one another within + / - 10%, said rotational speed being equal to or substantially equal to the rotational speed corresponding to the determined acoustic threshold 60 of at least one compression device.

[0081] The compression device rotates at this speed so that the first cooling capacity 73 reaches the first cooling target 71 as quickly as possible. As long as the first cooling capacity 73 has not reached the first cooling target 71, the second opening cross section 82 remains closed, so that only the first branch is supplied with refrigerant, giving priority to cooling the electric storage device. The first cooling capacity 73 reaches the first cooling target 71 at a second time t92. From this second time t92 onward, the second opening cross section 82 of the second expansion member at least partially opens, causing refrigerant to circulate in the second branch and thus provide cooling for the vehicle interior using the second heat exchanger. If the first branch is no longer able to adequately cool the electric storage device in this new configuration, the second opening cross section 82 of the second expansion member closes again, causing refrigerant to circulate only in the first branch.

[0082] pass Figure 4 and Figure 5 The second example explained corresponds to a case where the electric storage device and the vehicle interior require cooling, with cooling of the electric storage device requiring priority, although this example can also be transformed to a case where cooling of the vehicle interior requires priority.

[0083] Figure 6Schematic diagram of refrigerant circulation in a circuit according to a third example, in which cooling of the electric storage device and the vehicle interior is required, with no particular preference given to either. In this third example, refrigerant FR circulates between a first branch 4 and a second branch 5, each of which is required to achieve its own specific cooling target. In this regard, first expansion member 8 and second expansion member 12 are at least partially open, allowing refrigerant FR to pass through first heat exchanger 10 for cooling electric storage device 11 and second heat exchanger 14 for cooling the vehicle interior, respectively. According to this third example, the control module acts on the rotational speeds of compression devices 9 and 13, as well as the opening cross-sections of control device 16, first expansion member 8, and second expansion member 12. Modifying the opening cross-section of control device 16 allows refrigerant FR to be distributed between first branch 4 and second branch 5 according to the activity of first compression device 9 and second compression device 13.

[0084] Figure 7 Shown are the time curves of the rotational speed of the compression device, the curves of the refrigeration capacity of the two branches of the refrigerant circuit relative to their cooling targets, and the curves of the opening cross section of the control device of the refrigerant circuit.

[0085] Figure 7 The top curve makes it possible to monitor how the first speed 61 of the first compression means and the second speed 62 of the second compression means vary over time. The middle curve makes it possible to monitor how the first cooling capacity 73 of the first branch develops to meet the first cooling target 71, and how the second cooling capacity 74 of the second branch develops to meet the second cooling target 72, the latter addressing a cooling demand of the vehicle interior, for example following a request from a vehicle occupant. Figure 7 The bottom curve itself shows how the third opening cross section 83 of the control device evolves, in particular how the opening cross section of the expansion device evolves.

[0086] In this method, to meet the cooling requirements of the electrical storage device and the vehicle interior, respectively, the first speed 61 of the first compression device and the second speed 62 of the second compression device are increased. This has the effect of increasing the first cooling capacity 73 of the first branch and the second cooling capacity 74 of the second branch, assuming that the cooling capacity depends in part on the speed of the compression device associated with it. At the same time, the control device assumes an arbitrary third opening cross section 83 and, in this case, is closed, for example.

[0087] At the third time t93, the second cooling capacity 74 reaches the second cooling target 72. This means that the vehicle interior is sufficiently cooled. From the third time t93 onward, the second rotational speed 62 of the second compression device stabilizes. However, at the third time t93, the first cooling capacity 73 has not yet reached the first cooling target 71. Therefore, the first compression device continues to increase its first rotational speed 61.

[0088] This method continues until a fourth moment t94. At this fourth moment t94, the first rotational speed 61 of the first compression device reaches a rotational speed corresponding to the determined acoustic threshold 60 of the at least one compression device. As described above, the first rotational speed 61 cannot be increased at this stage, as this would generate noise pollution. However, it will be noted that at the fourth moment t94, the first cooling capacity 73 still does not reach the first cooling target 71. To remedy this, the second compression device increases its second rotational speed 62 to help increase the first cooling capacity 73 so that the first cooling capacity 73 can reach the first cooling target 71. During the method, this occurs by converging the first rotational speed 61 and the second rotational speed 62 so that both reach the rotational speed corresponding to the determined acoustic threshold 60 of the at least one compression device.

[0089] At the same time, the third opening cross section 83 of the control device, in particular the opening cross section of the expansion device, gradually opens further, allowing the refrigerant to flow from the first branch to the second branch in the pipeline, thereby allowing the second compression device to receive sufficient refrigerant and increase its second rotational speed 62, thereby contributing to the cooling of the first branch, allowing the first branch to reach the first cooling target 71. Once the first cooling capacity 73 reaches the first cooling target 71 at the fifth time t95, the third opening cross section 83 of the control device maintains its opening degree constant.

[0090] Of course, the invention is not limited to the examples that have just been described and various modifications may be made to these examples without departing from the scope of the invention.

[0091] As just described, the present invention successfully achieves the objectives it set itself and makes it possible to propose a method for regulating a refrigerant circuit comprising at least two compression devices, making it possible to regulate the temperatures of a plurality of different entities without causing noise pollution from the compression devices and without causing their rotational speeds to converge. Variants not described here may be implemented without departing from the invention, provided that they include the regulation method according to the invention.

Claims

1. A method for regulating a refrigerant (FR) circuit (1) of a motor vehicle, the circuit comprising at least a first branch (4) and a second branch (5), the first branch (4) being provided with a first heat exchanger (10) configured to thermally condition an electrical storage device (11) of the vehicle and a first compression device (9) associated with the first branch (4), the second branch (5) being provided with a second heat exchanger (14) configured to thermally treat the interior of the vehicle and a second compression device (13) associated with the second branch (5), the compression devices (9, 13) being able to rotate at a variable speed in order to meet variable cooling targets (71, 72) of the branches (4, 5), characterized in that During the method: - in a step, the rotational speed (61, 62) of at least one compression device (9, 13) is increased to a rotational speed corresponding to a determined acoustic threshold (60), as long as the cooling target (71, 72) of the branch (4, 5) to which the compression device (9, 13) is associated has not yet been reached, - In a further step, if the cooling target (71, 72) of the branch (4, 5) to which the compression device (9, 13) is associated is not reached when the rotational speed (61, 62) of the compression device (9, 13) reaches a rotational speed corresponding to a determined acoustic threshold (60), the rotational speeds (61, 62) of the compression device (9, 13) are converged until these speeds are identical within + / - 10%.

2. A method for regulating a refrigerant (FR) circuit (1) of a motor vehicle according to claim 1, during which it is determined whether a cooling target (71, 72) for cooling the branch (4, 5) to which the compression device (9, 13) is associated is achieved by comparing the cooling capacity (73, 74) of the branch (4, 5) with said cooling target (71, 72) of the branch (4, 5) to which the compression device (9, 13) is associated.

3. A method for regulating a refrigerant (FR) circuit (1) of a motor vehicle according to any one of the preceding claims, during which the refrigerant (FR) circuit (1) is capable of circulating the refrigerant (FR) from a first branch (4) to a second branch (5), the refrigerant (FR) circuit (1) comprising a pipe (15) providing a connection between the first branch (4) and the second branch (5), said pipe (15) being provided with a control device (16) capable of regulating the passage of the refrigerant (FR) from one branch (4, 5) to the other.

4. A method for regulating a refrigerant (FR) circuit (1) of a motor vehicle as claimed in claim 3, during which the control device (16) allows the refrigerant (FR) to circulate in the pipe (15) when the first compression device (9) reaches a rotational speed corresponding to a determined acoustic threshold (60) without having to meet the first cooling target (71) of the first branch (4), and when the second compression device (13) is not working or rotates at a speed lower than the rotational speed corresponding to the determined acoustic threshold (60).

5. A method for regulating a refrigerant (FR) circuit (1) of a motor vehicle as claimed in claim 4, during which the first compression device (9) and the second compression device (13) converge to a rotational speed (61, 62) below the rotational speed corresponding to a determined acoustic threshold (60), the first rotational speed (61) of the first compression device (9) decreasing and the second rotational speed (62) of the second compression device (13) increasing.

6. A method for regulating a refrigerant (FR) circuit (1) of a motor vehicle as claimed in any one of claims 4 and 5, during which, after the rotational speeds (61, 62) have converged, the respective rotational speeds (61, 62) of each compression device (9, 13) are increased in coordination with one another up to a rotational speed corresponding to a determined acoustic threshold (60), as long as the first cooling target (71) of the first branch (4) is not reached.

7. Method for regulating a refrigerant (FR) circuit (1) of a motor vehicle according to claim 4, during which the control device (16) regulates the circulation of the refrigerant (FR) in the pipe (15) according to the variable opening cross section.

8. Method for regulating a refrigerant (FR) circuit (1) of a motor vehicle according to claim 7, wherein When the first compression device (9) reaches a rotational speed corresponding to a determined acoustic threshold (60) without satisfying the first cooling target (71) of the first branch (4), and as long as the second compression device (13) rotates at a speed lower than the rotational speed corresponding to the determined acoustic threshold (60), the opening cross section of the control device (16) is increased.

9. A thermal management system (100) comprising a refrigerant (FR) circuit (1) implementing the method for regulating a refrigerant (FR) circuit (1) of a motor vehicle as claimed in any one of the preceding claims.

10. Thermal management system (100) according to the preceding claim, comprising a control module (50) configured to manage the implementation of the regulation method.

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