Method for controlling a refrigerant fluid circuit for temperature control of a passenger compartment, in particular of a motor vehicle

Abstract

The present invention relates to a method for controlling the temperature of a passenger compartment using a temperature control system, particularly a passenger compartment of a motor vehicle, the system comprising a refrigerant fluid circuit configured to perform a thermodynamic cycle, the circuit including a first branch and a second branch extending in parallel, the first branch for exchanging heat with a first heat transfer fluid and the second branch for exchanging heat with a second heat transfer fluid, the circuit being configured to alternately supply only the first branch according to a first operating mode called a simple dehumidification operating mode (100) such that the passenger compartment can be dehumidified via the first heat transfer fluid, and to simultaneously supply the first branch and the second branch according to a second operating mode called a parallel dehumidification operating mode (102) such that the passenger compartment can be dehumidified via the first heat transfer fluid and heat energy extracted from the second heat transfer fluid, the system being configured to supply a temperature control fluid to the passenger compartment using a mixture of external airflow and airflow from the passenger compartment according to a supply mode called a recirculation supply mode, the method comprising the step of determining an operating mode from the simple dehumidification mode (100) and the parallel dehumidification mode (102) such that the determined operating mode occurs at least under the recirculation supply mode according to conditions.

Description

Technical Field

[0001] The present invention relates to a method for controlling a refrigerant fluid circuit for temperature control of a passenger compartment, particularly a passenger compartment of a motor vehicle. Background Technology

[0002] In this field, a known approach is to control the temperature of the passenger compartment using a refrigerant fluid loop that operates in a thermal cycle in heat pump or air conditioning mode. The refrigerant exchanges heat with an airflow intended to enter the passenger compartment. By heating or cooling the airflow with the refrigerant, the passenger compartment can thus be heated or cooled.

[0003] Furthermore, in the event of fogging and / or frost on passenger cabin windows (particularly windshields), heat exchange provides dry air and, if necessary, provides hot air to be exhausted onto the windows for defogging and / or de-icing. Similarly, if the air used to generate the airflow contains excessive moisture, heat exchange allows it to be dried before being delivered into the passenger cabin. Therefore, it is known to control the refrigerant fluid circuit to dehumidify the airflow, with the refrigerant designed to exchange heat with the airflow.

[0004] To this end, a refrigerant fluid loop has been proposed, comprising a first branch and a second branch extending in parallel. The first branch is used for heat exchange with an airflow flowing towards the passenger compartment, and the second branch is used for heat exchange with an external airflow. The loop is configured to alternately supply only the first branch according to a first operating mode, called a single dehumidification mode, thereby allowing dehumidification of the passenger compartment, and to simultaneously supply the first and second branches according to a second operating mode, called a parallel dehumidification mode, thereby allowing dehumidification of the passenger compartment and heat extraction from the external airflow. The heat extracted from the external airflow allows the airflow flowing towards the passenger compartment to be heated more after drying than in the single dehumidification mode.

[0005] Another known practice is to generate airflow to the passenger compartment using only external airflow or a mixture of said external airflow and airflow from the passenger compartment, according to a supply mode known as a recirculation supply mode.

[0006] Using recirculation mode for supply has the advantage of improving energy performance. However, it is considered risky if the purpose is defogging and / or de-icing. Summary of the Invention

[0007] The object of the present invention is to at least partially overcome the aforementioned disadvantages, and to this end, the present invention proposes a method for controlling the temperature of a passenger compartment, particularly a passenger compartment of a motor vehicle, by means of a temperature control system. The system includes a refrigerant fluid circuit configured to perform a thermodynamic cycle. The circuit includes a first branch and a second branch extending in parallel. The first branch is used for heat exchange with a first heat transfer fluid, and the second branch is used for heat exchange with a second heat transfer fluid. The circuit is configured to alternately supply only the first branch according to a first operating mode, called a single dehumidification mode, thereby allowing dehumidification of the passenger compartment by means of the first heat transfer fluid, and simultaneously supply the first and second branches according to a second operating mode, called a parallel dehumidification mode, thereby allowing dehumidification of the passenger compartment by means of the first heat transfer fluid and heat energy extraction from the second heat transfer fluid. The system is configured to supply a temperature control fluid to the passenger compartment by means of a mixture of external airflow and airflow from the passenger compartment according to a supply mode, called a recirculation supply mode. The method includes the step of determining an operating mode from the single dehumidification and parallel dehumidification modes, such that the determined operating mode conditionally occurs at least in the recirculation supply mode.

[0008] Based on the applicant's observations, the present invention can dehumidify the air even during recirculation. Furthermore, according to the method of the present invention, by utilizing various dehumidification strategies and determining the strategy to be used in consideration of usage conditions (particularly the passenger compartment heating setpoint), air recirculation can be achieved simultaneously with dehumidification in a wide range of situations. Therefore, the present invention allows for a significant improvement in energy efficiency through the wider use of air recirculation.

[0009] According to various additional features of the invention, which may be used together or individually and form many embodiments of the invention: - If the temperature of the mixture of external airflow and airflow from the passenger cabin, referred to as the upstream temperature, is higher than the limit temperature, then the step of determining the operating mode provides a transition from a parallel dehumidification mode to a single dehumidification mode. - If the upstream temperature is lower than the limit temperature minus the switching variable, the step of determining the operating mode provides a transition from a single dehumidification mode to a parallel dehumidification mode. - The switching variable depends on the flow rate of the fluid used for temperature control of the passenger compartment and / or depends on the external temperature. - The step of determining the operating mode provides one or more of the following additional parameters to be considered: o The temperature difference between the external airflow and the airflow from the passenger compartment. o The temperature of the external airflow, o The flow rate of the fluid used for temperature control in the passenger compartment o The flow rate of the refrigerant, o The opening rate of the refrigerant expansion valve in the second branch, - When the temperature-controlled fluid is supplied at a low flow rate for recirculation, the step of determining the operating mode tends to select a single dehumidification mode. The method includes the step of determining a supply mode that allows setting a maximum amount of airflow from the passenger compartment. - The step of determining the supply mode takes into account the flow rate of the fluid used for temperature control in the passenger cabin. - The step of determining the supply mode uses a data file, which includes the maximum value of the flow rate of the airflow from the passenger compartment for the fluid used for temperature control of the passenger compartment, optionally expressed as a ratio to the sum of the flow rates of the external airflow and the airflow from the passenger compartment. The system allows for the alternating supply of fluid for passenger cabin temperature control using only external airflow, under one supply mode called a no-reflow supply mode, and another supply mode based on reflow. - The step of determining the supply mode also allows for selection between a recirculation supply mode and a non-recirculation supply mode. The method includes the step of controlling the expansion valve of the second branch in the parallel dehumidification mode. - The control steps enable the refrigerant flow rate to be varied within a range from zero to a maximum value. - The first branch includes a first heat exchanger for heat exchange between the refrigerant and the first heat transfer fluid. - The second branch includes a second heat exchanger for heat exchange between the refrigerant and the second heat transfer fluid. The circuit includes a first two-fluid exchanger supplying the first branch and the second branch, the first two-fluid exchanger being used for heat exchange between the refrigerant and another heat transfer fluid. - The other fluid is used for temperature control in the passenger cabin. - The other heat transfer fluid is the first heat transfer liquid. The system includes a radiator for heat exchange between a first heat transfer fluid and a fluid for temperature control of the passenger compartment. The system includes a first loop for a first heat transfer liquid, the first loop including the first two-fluid exchanger and the heating radiator. - The first fluid is used for temperature control in the passenger compartment. - The first fluid is the second heat transfer liquid. - The first heat exchanger forms a second two-fluid exchanger for heat exchange between the refrigerant and the second heat transfer liquid. The system includes a cooling radiator, through which the second heat transfer fluid and the fluid used for temperature control of the passenger compartment pass. The system includes a second loop for a second heat transfer liquid, the second loop including the second dual-fluid exchanger and the cooling radiator. Attached Figure Description

[0010] The invention will be better understood in the following detailed explanatory description of at least one embodiment provided by way of purely illustrative and non-limiting example, with reference to the accompanying schematic diagrams, and further objects, details, features, and advantages of the invention will become clearer, wherein: Figure 1 An example of a refrigerant fluid circuit used in the method according to the invention in a single dehumidification mode is schematically depicted [Note: it will be adjusted with the last figure]; Figure 2 An example of a refrigerant fluid circuit used in the method according to the invention in parallel dehumidification mode is schematically depicted [Note: it will be adjusted with the last figure]; Figure 3 A first embodiment of the method according to the present invention is illustrated schematically. Detailed Implementation

[0011] First, it should be noted that the terms "upstream" and "downstream" used in the following description refer to the direction of flow of the fluid in question. Furthermore, the terms "first," "second," "third," etc., are used only to distinguish the components in question and do not indicate any order or possible importance of the components.

[0012] This invention relates to a method for controlling the temperature of a passenger compartment, particularly a passenger compartment of a motor vehicle. The vehicle includes an electric motor that provides motor torque to the vehicle's drive wheels; the vehicle is particularly an electric or hybrid motor vehicle. The electric motor is supplied with current at least by a battery (referred to as a traction battery).

[0013] like Figure 1 and Figure 2 As shown, the passenger compartment temperature control operates using a temperature control system. This system is configured to heat-treat a fluid I, referred to as a temperature control fluid, which forms an airflow intended to be delivered into the passenger compartment. For this purpose, the system includes a heating, ventilation, and / or air conditioning housing 2 configured to allow the temperature control fluid to pass through it. In the case of a passenger compartment in a motor vehicle, the housing 2 is intended to be located, for example, below the vehicle's dashboard.

[0014] The system includes a refrigerant fluid circuit 10. The refrigerant is, for example, a hydrofluorocarbon, such as R-134a, or a fluid referred to as R1234yf. Alternatively, it is carbon dioxide, also known as R744.

[0015] The loop 10 is configured to perform a thermodynamic cycle that successively includes a compression phase, a first heat exchange phase with decreasing enthalpy, an expansion phase, and a second heat exchange phase with increasing enthalpy.

[0016] The loop 10 includes a first branch 12 and a second branch 14, which extend in parallel between a first bypass point 16 and a second junction point 18. The first branch 12 is used for heat exchange with a first heat transfer fluid. The second branch 14 is used for heat exchange with a second heat transfer fluid.

[0017] As will be explained below, the circuit 10 is configured to alternately supply only the first branch 12 according to a first operating mode, called a single dehumidification mode, thereby allowing dehumidification of the passenger compartment by means of a first heat transfer fluid, and to simultaneously supply the first branch 12 and the second branch 14 according to a second operating mode, called a parallel dehumidification mode, thereby allowing dehumidification of the passenger compartment by means of the first heat transfer fluid as in the first case. This second operating mode also allows heat energy to be extracted from the second heat transfer fluid.

[0018] The first branch 12 includes a first heat exchanger 30 for heat exchange between the refrigerant and the first heat transfer fluid.

[0019] In this configuration, the refrigerant fluid circuit includes a first dual-fluid exchanger 20 that supplies refrigerant to the first branch 12 and the second branch 14. It is connected downstream, directly or indirectly, to the first bypass point 16. The first dual-fluid exchanger 20 is used for heat exchange between the refrigerant and another heat transfer fluid.

[0020] In the illustrated embodiment, the first heat transfer fluid that exchanges heat with the refrigerant in the first heat exchanger 30 is a temperature-controlled airflow I. In other words, the first heat exchanger 30 is located within the housing 2. It is formed, for example, by an evaporator or a gas heater.

[0021] The other heat transfer fluid that exchanges heat with the refrigerant in the first two-fluid exchanger 20 is the first heat transfer liquid. This is, for example, water with added antifreeze, such as ethylene glycol.

[0022] According to this variant, the system includes a heating radiator 21 for heat exchange between a first heat transfer liquid and a fluid I for temperature control of the passenger compartment. For this purpose, the system advantageously includes a first loop (not shown) for the first heat transfer liquid. The first loop includes the first two-fluid exchanger 20 and the heating radiator 21. The first two-fluid exchanger is formed, for example, by a condenser or gas cooler referred to as a water condenser or gas cooler.

[0023] According to another variant (not shown), the other fluid that exchanges heat with the refrigerant in the dual-fluid exchanger 20 is directly fluid I used for temperature control of the passenger compartment. According to this variant, the first dual-fluid exchanger 20 is located within the housing 2. This is, for example, a condenser or gas cooler referred to as an internal condenser or gas cooler.

[0024] According to an alternative embodiment (not shown), the first fluid that exchanges heat with the refrigerant in the first heat exchanger 30 is a second heat transfer liquid, which may have the same properties as the first heat transfer fluid described above.

[0025] Then, the first heat exchanger located in the first branch 12 forms a second two-fluid exchanger for heat exchange between the refrigerant and the second heat transfer fluid. The system includes a cooling radiator through which the second heat transfer fluid and the fluid used for passenger compartment temperature control pass. The cooling radiator is housed in a casing 2, replacing the aforementioned evaporator or gas heater. For this purpose, the system advantageously includes a second loop for the second heat transfer fluid. The second loop includes the first heat exchanger of the first branch 12 and the cooling radiator.

[0026] Refer again Figure 1 and Figure 2 As can be seen, the second branch 14 includes a second heat exchanger 22 for heat exchange between the refrigerant and the second heat transfer fluid. In this case, the second heat transfer fluid is formed by an airflow referred to as the external airflow E. The second heat exchanger 22 specifically includes a condenser or gas cooler. It is located, for example, on the front surface of the vehicle, behind the grille, or under the hood.

[0027] In this configuration, the refrigerant fluid circuit 10 includes, in the direction of refrigerant flow, a compressor 40, a first dual-fluid exchanger 20, a refrigerant fluid storage device 42, the bifurcation point 16, a first expansion member 44, a first heat exchanger 30, and the first confluence point 18 in the main refrigerant fluid loop.

[0028] The loop 10 may also optionally include a heat exchanger 46, referred to as an internal heat exchanger, thereby allowing heat exchange between the refrigerant and itself at different pressure levels. The internal heat exchanger 46 includes, for example, a first passage 46a and / or a second passage 46b, through which high-pressure refrigerant is intended to pass, and through which low-pressure refrigerant is intended to pass. The first passage 46a is downstream of the storage device 42 and upstream of the bypass point 16 in the main loop. The second passage 46b is downstream of the junction point 18 and upstream of the compressor 40 in the main loop.

[0029] In this case, the first dual-fluid exchanger 20 is directly connected to the compressor 12, meaning there is no other heat exchanger between the compressor 12 and the first dual-fluid exchanger 20.

[0030] The second branch 14 includes, for example, a second expansion member 48 and a second heat exchanger 22 starting from the first bypass point 16, and then returning to the first confluence point 18.

[0031] In this configuration, the refrigerant fluid circuit 10 further includes a third branch 50, which is installed as a bypass connection between the first bypass point 16 and the first junction point 18. The third branch 50 includes, for example, a third expansion member 52 and another dual-fluid exchanger 54.

[0032] The other dual-fluid exchanger 54 is configured to allow heat exchange between a refrigerant and another fluid, such as for directly or indirectly cooling an electrical energy storage device and / or an electric motor in a vehicle. This type of heat exchanger is commonly referred to as a "cooler" by those skilled in the art.

[0033] Expansion members 44, 48, and 52 include, for example, electronic expansion valves.

[0034] The system is configured to supply fluid for passenger cabin temperature control via a mixture of external airflow I1 and airflow I2 from the passenger cabin, according to a supply mode known as a recirculation supply mode. This recirculation mode allows the thermal inertia of the air present in the passenger cabin to be used to limit the energy supplied to the temperature control system. The system is configured such that the external airflow I1 and the passenger cabin airflow I2 are mixed, for example, upstream of the first heat exchanger 12 in the direction of the temperature control airflow I, within the housing 2. The ratio of each of flows I1 and I2 determines the temperature of the air entering the first exchanger 30, or, where appropriate, the cooling exchanger, based on the external temperature and the passenger cabin temperature.

[0035] The system is also configured to alternately supply fluid I for passenger cabin temperature control using only external airflow I1 according to another supply mode called the no-reflow supply mode, and according to the reflow supply mode.

[0036] Figure 1 The operation of the refrigerant fluid loop in a single dehumidification mode is illustrated. In this mode, the refrigerant acquires heat energy from the temperature-controlled airflow I via a first heat exchanger 30 and transfers it to the other heat transfer fluid via the refrigerant fluid loop 10 via a first dual-fluid exchanger 20. Therefore, the temperature-controlled airflow I can be dried by cooling it. Furthermore, if desired, the heat energy supplied to the other heat transfer fluid allows the temperature-controlled airflow I to be reheated via the aforementioned first heat transfer fluid loop after it has been dried.

[0037] In this operating mode, starting from compressor 40, the refrigerant passes through the first dual-fluid exchanger 20 following the main circuit. This first dual-fluid exchanger 20 acts as a condenser or gas cooler, exchanging heat with another heat transfer fluid to dissipate the thermal energy from the refrigerant within that other heat transfer fluid. It then passes through the storage device 42 and the high-pressure passage 46a of the internal exchanger 46. At the first bypass point 16, the refrigerant passes only through the first branch 12, and the second expansion member 48 is closed.

[0038] Since the third expansion member 52 is also closed, the refrigerant continues downstream toward the first expansion member 44, which is set to be activated. Therefore, it undergoes expansion and then passes through the first heat exchanger 30, which operates as an evaporator and / or gas heater. As described above, the refrigerant thus dries the temperature control airflow I by cooling it. The refrigerant then returns to the compressor 12 through the first junction 18 and the low-pressure passage 46b of the internal heat exchanger 46.

[0039] Figure 2The operation of the refrigerant fluid loop in parallel dehumidification mode is illustrated. In this case, on the one hand, as in the mode of operation in single dehumidification mode, the refrigerant acquires heat energy from the temperature-controlled airflow I by means of the first heat exchanger 30 and transfers it to the other heat transfer fluid via the refrigerant fluid loop 10 by means of the first dual-fluid exchanger 20. On the other hand, the refrigerant acquires heat energy from the external airflow E so that it can be transferred to the refrigerant by means of the second exchanger 22. Therefore, the temperature-controlled airflow I can be further dried by cooling the temperature-controlled airflow I. In particular, the heat energy supplied by the external fluid E also enables the temperature-controlled airflow I to be further heated by means of the first heat transfer liquid loop after drying.

[0040] In this operating mode, starting from compressor 40, the refrigerant exchanges heat with another heat transfer fluid through a first two-fluid exchanger 20, which acts as a condenser or gas cooler, so as to dissipate the heat energy from the refrigerant in the other heat transfer fluid. It then passes through the storage device 42 and the high-pressure passage 46a of the internal exchanger 46. At the first bypass point 16, the refrigerant is then split into two parts so that it passes through both the first branch 12 and the second branch 14.

[0041] As described above, along the first branch 12, the refrigerant passes through the first expansion member 44, which is configured to be activated. Therefore, it undergoes expansion and then passes through the first heat exchanger 30, which operates as an evaporator and / or gas heater. As described above, the refrigerant thus dries the temperature control airflow I by cooling it. Along the second branch 14, the refrigerant passes through the second expansion member 48, which is configured to be activated, and the second heat exchanger 22, which functions as an evaporator and / or gas heater. As described above, the refrigerant thus captures heat energy from the external airflow E.

[0042] The test results are given in the table below, which indicates whether a given operating mode allows for satisfactory defogging under certain conditions, namely the temperature Tu (upstream temperature) of the temperature control fluid I before it passes through the evaporator 30 and the flow rate Q of the passenger cabin temperature control fluid I. The temperature Tu is expressed in degrees Celsius in the rows. The flow rate Q is expressed in kilograms per hour in the columns.

[0043] The temperature Tu, measured before passing through evaporator 30, corresponds to the air recirculation rate indicated in parentheses next to the value of temperature T. The air recirculation rate is defined as the velocity of the airflow I2 from the passenger compartment divided by the total velocity of the fluid used for passenger compartment temperature control, generated by the airflow I1 from the outside and the airflow I2 from the passenger compartment. In other words, for example, for a 40% ratio (corresponding to a temperature Tu value of 22°C), the airflow for passenger compartment temperature control is generated by a mixture of 40% airflow from the passenger compartment and 60% airflow from the outside. For this test, the outside air temperature is 0°C. The velocity of the outside airflow E and the compression level provided by compressor 40 are constant.

[0044] The "DS" in the cell refers to the single dehumidification mode's ability to achieve good demisting under the conditions of temperature Tu and flow rate Q in the corresponding cell.

[0045] The "DP" in the cell indicates that the parallel dehumidification mode can achieve good demisting under the conditions of temperature Tu and flow rate Q in the corresponding cell.

[0046] The cell marked DS / DP corresponds to the critical situation between single dehumidification mode and parallel dehumidification mode.

[0047] The "X" in the cell indicates that, under the conditions of temperature T and flow rate Q in the corresponding cell, neither the single dehumidification mode nor the parallel dehumidification mode can achieve satisfactory demisting.

[0048]

[0049] This table illustrates that air recirculation is possible in passenger cabin dehumidification mode, and that using different dehumidification modes allows for an expanded operating range associated with this combination. Temperature-controlled total airflow velocity and / or recirculation rate influence the selected operating mode. For a given upstream temperature Tu, a single dehumidification mode can be used as long as the airflow velocity Q remains relatively low, while at velocities above a certain Q, it is necessary to switch to a parallel dehumidification mode. Similarly, for a given velocity Q, a single dehumidification mode can be used as long as the recirculation rate remains relatively low, while at velocities above a certain recirculation rate, it is necessary to switch to a parallel dehumidification mode.

[0050] It can also be seen that for a given flow rate Q, the lower the external temperature and / or the higher the heating setpoint, the more necessary it is to use the parallel dehumidification mode, which will result in a given upstream temperature Tu due to air recirculation.

[0051] Furthermore, above certain values, neither mode is compatible with air recirculation.

[0052] like Figure 3As shown, according to the present invention, the method for temperature control of the passenger cabin temperature control airflow utilizes the above-mentioned observations. Therefore, it includes the step of determining an operating mode from a single dehumidification 100 mode and a parallel dehumidification 102 mode, such that the determined operating mode occurs at least in the recirculation supply mode, taking into account usage conditions.

[0053] Preferably, the method includes the step of determining the upstream temperature Tu from the mixture of external airflow I1 and airflow I2 from the passenger compartment; in other words, here, as described above, the temperature of the temperature control airflow I upstream of the first heat exchanger 30 is determined.

[0054] If the upstream temperature is higher than the limit temperature TI, the step of determining the operating mode provides a transition 104 from parallel dehumidification mode 102 to single dehumidification mode 100.

[0055] Conversely, if the upstream temperature is lower than the limit temperature TI, but this time the switching variable Tb is subtracted, the step of determining the operating mode provides a transition 106 from single dehumidification mode 100 to parallel dehumidification mode 102. For consistency, the switching variable Tb is also temperature.

[0056] In other words, according to the described mode of implementation, if the system was in a single dehumidification mode or a parallel dehumidification mode at a previous moment, the transition from one operating mode to another will not be triggered by the same temperature value. In other words, the transition from one operating mode to another takes into account the system's state at the previous moment. This shift provides optimal energy efficiency in single dehumidification mode over a wider operating range.

[0057] Advantageously, the switching variable depends on the flow rate of fluid I used for temperature control of the passenger compartment and / or on the external temperature. For temperatures Tu and TI expressed in °C, the switching variable Tb is, for example, between 0 and 5 °C.

[0058] Preferably, the step of determining the operating mode further includes considering one or more of the following additional parameters: - The temperature difference between the outside airflow and the airflow from the passenger compartment. - The temperature of the external airflow, - The flow rate of the fluid used for temperature control in the passenger compartment. - The flow rate of the refrigerant, - The opening rate of the refrigerant expansion valve in the second branch.

[0059] Note that the present invention enables control to be implemented using all or some of the information described above, without relying on information about the humidity level in the passenger cabin.

[0060] Preferably, the method further includes a step of determining a supply mode between a recirculation supply mode and a non-recirculation supply mode. This step of determining the supply mode results in the selection of a non-recirculation mode, for example, when neither a single dehumidification mode nor a parallel dehumidification mode can operate with a certain proportion of air from the passenger compartment, and without creating too high a risk of fogging and / or failing to reach the desired temperature setpoint.

[0061] The step of determining the supply mode takes into account the flow rate of fluid I used for temperature control of the passenger compartment. Advantageously, the determination step uses a data file for the value of the flow rate Q of the fluid used for temperature control of the passenger compartment, which includes the maximum value of the flow rate of airflow I2 from the passenger compartment, optionally expressed as a ratio to the sum of the flow rates of external airflow I1 and airflow I2 from the passenger compartment, i.e., the aforementioned recirculation rate.

[0062] The file is, for example, in the form of a data table. An example of such a file is given below:

[0063] In this table, the left-hand column represents the value of the flow rate Q in kilograms per hour, and the right-hand column represents the maximum air reflow ratio corresponding to the flow rate Q. For example, for a flow rate Q of 150 kg / h, the reflow ratio should not exceed 40%.

[0064] Preferably, when the temperature-controlled fluid is supplied at a low flow rate for recirculation, the step of determining the operating mode tends to select a single dehumidification mode. This should be understood to mean, for example, a flow rate of less than 250 kg / h.

[0065] The method advantageously includes the step of controlling the expansion valve of the second branch 14 at least in the parallel dehumidification mode. This control step allows, for example, the refrigerant flow rate to be varied within a range from zero to a maximum value. Zero flow rate corresponds to a configuration in which no refrigerant circulates in the second branch 14, such as configurations encountered particularly in single dehumidification mode operation. A strictly positive flow rate corresponds to an operation mode with refrigerant expansion up to a specific value, such as configurations encountered particularly in parallel dehumidification mode operation. Maximum flow rate corresponds to another operation mode in which the refrigerant circulates in the second branch 14 without expansion. This could be, for example, a passenger cabin air conditioning mode.

Claims

1. A method for controlling the temperature of a passenger compartment, particularly a passenger compartment of a motor vehicle, by means of a temperature control system, the system comprising a refrigerant fluid circuit (10) configured to perform a thermodynamic cycle, the circuit (10) comprising a first branch (12) and a second branch (14) extending in parallel, the first branch (12) for heat exchange with a first heat transfer fluid, the second branch (14) for heat exchange with a second heat transfer fluid, the circuit being configured to alternately supply only the first branch (12) according to a first operating mode called a single dehumidification mode (100), thereby allowing the temperature of a passenger compartment to be controlled by means of a refrigerant fluid circuit (10). The passenger compartment is dehumidified by a hot fluid, and the first branch (12) and the second branch (14) are simultaneously supplied according to a second operating mode called parallel dehumidification mode (102), thereby allowing the passenger compartment to be dehumidified by means of the first heat transfer fluid and heat energy to be obtained from the second heat transfer fluid. The system is configured to supply a temperature-controlled fluid to the passenger compartment by means of a mixture of external airflow and airflow from the passenger compartment according to a supply mode called recirculation supply mode. The method includes the step of determining an operating mode from a single dehumidification mode and a parallel dehumidification mode, such that the determined operating mode conditionally occurs at least in the recirculation supply mode.

2. The method according to claim 1, wherein, If the temperature (Tu) of the mixture of the external airflow and the airflow from the passenger compartment, referred to as the upstream temperature, is higher than the limit temperature (Tl), then the step of determining the operating mode provides a transition (104) from the parallel dehumidification mode (102) to the single dehumidification mode (100).

3. The method according to any one of the preceding claims, wherein, If the upstream temperature (Tu) is lower than the limit (Tl) minus the switching variable (Tb), the step of determining the operating mode provides a transition (106) from a single dehumidification mode (100) to a parallel dehumidification mode.

4. The method according to the preceding claim, wherein, The switching variable (Ts) depends on the flow rate of the fluid used for temperature control of the passenger compartment and / or depends on the external temperature.

5. The method according to any one of the preceding claims, wherein, The step of determining the operating mode provides one or more of the following additional parameters to be considered: - The temperature difference between the external airflow and the airflow from the passenger compartment. - The temperature of the external airflow, - The flow rate of the fluid used for temperature control of the passenger compartment. - The flow rate of the refrigerant, - The opening rate of the refrigerant expansion valve in the second branch.

6. The method according to any one of the preceding claims, wherein, When the temperature-controlled fluid is supplied at a low flow rate for recirculation, the step of determining the operating mode tends to select a single dehumidification mode (100).

7. The method according to any one of the preceding claims, wherein, The method includes the step of determining a supply mode that enables the setting of a maximum amount of airflow from the passenger compartment.

8. The method according to the preceding claim, wherein, The step of determining the supply mode takes into account the flow rate of the fluid used for temperature control of the passenger cabin.

9. The method according to the preceding claim, wherein, The determining step uses a data file for the flow rate of the fluid used for temperature control of the passenger compartment. The data file includes the maximum value of the flow rate of the airflow from the passenger compartment, optionally expressed as a ratio to the sum of the flow rates of the external airflow and the airflow from the passenger compartment.

10. The method according to any one of claims 7 to 9, wherein the system (10) enables the fluid for temperature control of the passenger compartment to be supplied alternately by means of the external airflow according to another supply mode called a non-reflow supply mode, and to be supplied according to a reflow supply mode, wherein the step of determining the supply mode further enables selection between the reflow supply mode or the non-reflow supply mode.

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