Control method for maximizing thermal power

Abstract

The invention relates to a method (2) for controlling a refrigerant circuit (1), comprising at least one compression device (3), a first heat exchanger (4), a second heat exchanger (5), an expansion device (6), and an accumulation device (7). The method (2) comprises a step (E1) for determining a value of a quantity representative of a high pressure (HP), and a step (E2) for comparing said value with a maximum threshold value (HPmax). The method (2) comprises a mode for maximizing thermal power. The transition to said mode comprises a step (E12) for increasing the degree of opening (DO) of the expansion device (6) and a step (E13) for increasing the velocity (Ncpr) of the compression device (3). This transition is carried out under at least one condition including exceeding or reaching the maximum threshold value (HPmax). Abstract Figure: Figure 2

Description

Title of the invention: Control method for maximizing thermal power. Technical field

[0001] The field of the present invention is that of refrigerant circuits and heat treatment systems including such refrigerant circuits, particularly for motor vehicles. Motor vehicles are commonly equipped with refrigerant circuits used to heat or cool different areas or components of the vehicle. It is known, in particular, to use a refrigerant circuit to heat an interior airflow sent into the vehicle's passenger compartment and / or a heat transfer fluid flow sent to the battery. Prior art

[0002] A refrigerant circuit is known to include a pair of heat exchangers designed to perform a thermodynamic cycle in order to provide energy capable of cooling the vehicle passenger compartment and / or the battery in the case of an electric vehicle, whether during vehicle operation while driving or when the vehicle is stationary. This pair of heat exchangers thus comprises one heat exchanger capable of functioning as an evaporator and another heat exchanger capable of functioning as a condenser. The heat exchanger capable of functioning as an evaporator may be an exchanger that allows heat exchange between refrigerant and air, and allows the passenger compartment to be cooled by means of a cooled interior airflow, this heat exchanger being traversed by this interior airflow which it thermally processes.The heat exchanger capable of functioning as an evaporator can also be a heat exchanger that allows heat exchange between a refrigerant and a heat transfer fluid, and allows, for example, the cooling of a battery using a flow of cooled heat transfer fluid. This heat exchanger is traversed by this flow of heat transfer fluid, which it thermally processes. As is known, this evaporator is part of a ventilation, heating, and / or air conditioning system installed in a vehicle.

[0003] Document FR3081086B1 presents an invention relating to a method for controlling such a type of automotive refrigerant circuit, enabling adequate cooling of the airflow while limiting the energy consumption associated with the operation of said circuit. Said refrigerant circuit comprises at least one refrigerant compression device, a first heat exchanger arranged to be traversed by an airflow from outside the vehicle's passenger compartment, and a second heat exchanger arranged to be traversed by a flow of interior air sent into the passenger compartment of the vehicle, a variable area expansion device disposed between the first heat exchanger and the second heat exchanger, an accumulation device disposed between the second heat exchanger and the compression device, the control method comprising at least one step of controlling the degree of opening of the expansion device, characterized in that the degree of opening controls an optimal subcooling setpoint "Tsbc" of the refrigerant at the outlet of the first heat exchanger, the subcooling setpoint "Tsbc" being calculated using at least one condensation temperature "Te" of the refrigerant at the outlet of the first heat exchanger, a temperature "Te" of the outside airflow and a coefficient "A", according to a formula defined such as [Tsbc = A x (Te - Te)], where the coefficient "A" is a function of a factor a between 0.68 and 1.

[0004] One drawback of this process is that it favors optimizing consumption at the expense of other potential optimization criteria. Summary

[0005] One aspect of the invention relates to a method for controlling a refrigerant circuit for a vehicle, said refrigerant circuit comprising at least one refrigerant compression device, a first heat exchanger arranged to be traversed by a flow of a first heat transfer fluid and intended to condense the refrigerant, a second heat exchanger arranged to be traversed by a flow of a second heat transfer fluid and intended to evaporate the refrigerant, a variable-section expansion member disposed between the first heat exchanger and the second heat exchanger, a refrigerant accumulation device disposed between the first heat exchanger and the compression device, the method comprising a step of determining a value of a quantity representative of a high pressure of the refrigerant between the outlet of the compression device and the inlet of the expansion member,the process also comprising a step of comparing the value of said representative high-pressure quantity with a maximum pressure threshold value, wherein the process comprises a mode for maximizing thermal power, the transition to said mode for maximizing thermal power comprising a step of increasing the degree of opening of the expansion member and a step of increasing the speed of the compression device, the transition to said mode being carried out under at least one transition condition, said at least one transition condition including exceeding or reaching the maximum pressure threshold value by said representative high-pressure quantity, said maximization of thermal power being, in a heat transfer fluid cooling mode, a maximization of the cooling power of the second heat transfer fluid in , the second heat exchanger, said process comprising preliminary steps to the transition to the cooling power maximization mode, said preliminary steps comprising a step of determining a second condensation temperature Te in the first heat exchanger, a step of determining a third temperature Te of the first heat transfer fluid upstream of the first heat exchanger, a step of calculating a minimum threshold subcooling Tsb_min from the value of the second condensation temperature of the refrigerant, from the value of the third temperature of the first heat transfer fluid upstream of the first heat exchanger, and from a first coefficient A such that [Tsb_min = A x (Tc-Te)], the first coefficient A having a value between 0.3 and 0.5 and preferably a value equal to 0.4,a step of determining the value of a fourth temperature Tscd of the refrigerant between the outlet of the first heat exchanger and the inlet of the expansion device, a step of calculating a subcooling Tsb such that said subcooling is equal to the difference between the second condensation temperature and the fourth temperature of the refrigerant at the outlet of the first heat exchanger, i.e. [Tsb=(Tc-Tscd)], and a step of comparing the value of the subcooling with the minimum subcooling threshold value, said at least one passing condition including said step of comparing the value of the subcooling, said at least one passing condition including the condition that a result of the step of comparing the value of the subcooling with the minimum subcooling threshold value is that the value of the subcooling is greater than the minimum subcooling threshold value.

[0006] This aspect of the invention aims to maximize the thermal cooling power of the second heat transfer fluid or the heating power of the first heat transfer fluid while respecting the system limitations such as the maximum pressure allowed at the outlet of the compression device.

[0007] The process 2 is applicable within a heat transfer fluid cooling mode and / or within a heat transfer fluid heating mode according to the mode being executed by the program configured to implement said process, with steps of said process 2 adapted to said mode.

[0008] According to particular embodiments, the process may comprise one or more of the following characteristics, taken individually or in all technically possible combinations: • the increase in the degree of opening of the expansion valve within the step of increasing the degree of opening of the expansion valve is controlled so that the value of the quantity representing the high pressure is equal to a pressure setpoint value when the value the representative value of the high pressure is greater than said pressure setpoint value; the pressure setpoint value is equal to the maximum pressure threshold value; said circuit includes a pressure sensor for measuring the pressure of the refrigerant fluid between the outlet of the compression device and the inlet of the expansion device, an output signal from said sensor being said value of a quantity representative of the high pressure; the process includes a step of determining a value of a first temperature of the second heat transfer fluid downstream of the second heat exchanger; the process includes a step of comparing the value of the first temperature with a cooling setpoint temperature value, said at least one passing condition including said step of comparing the value of the first temperature; said at least one passing condition includes the condition that a result of said step of comparing the value of the first temperature is that the value of the first temperature of the second heat transfer fluid downstream of the second heat exchanger is greater than the cooling setpoint temperature value + a, with a being a constant having as its preferred value a value between 0.2°C and 1°C; the speed of the compression device in the speed increase step of the compression device in the cooling power maximization mode is controlled so that the value of the first temperature of the second heat transfer fluid is between the cooling setpoint temperature value - a and the cooling setpoint temperature value + a, with a being a constant having as a preferred value a value between 0.2°C and 1°C, the method controlling the increase of the speed of the compression device when the value of the first temperature of the second heat transfer fluid is greater than the cooling setpoint temperature value + a, the method controlling the decrease of the speed of the compression device when the value of the first temperature of the second heat transfer fluid is less than the cooling setpoint temperature value Tsfc2c - a; The circuit includes a temperature sensor to measure the initial temperature of the second heat transfer fluid downstream of the second heat exchanger. of heat, an output signal from said temperature sensor being said first temperature value; the determination of the second condensation temperature in the step of determining the second condensation temperature in the first heat exchanger is carried out from the value of said quantity representing the pressure or another quantity representing the pressure of the refrigerant fluid in the first heat exchanger; the circuit includes a temperature sensor for measuring the temperature of the refrigerant fluid in the first heat exchanger, an output signal from said temperature sensor being said value of the second condensation temperature; the circuit includes a temperature sensor for measuring the third temperature of the first heat transfer fluid upstream of the first heat exchanger, an output signal from said temperature sensor being said third temperature value; the circuit includes a temperature sensor for measuring the fourth temperature of the refrigerant fluid between the outlet of the first heat exchanger and the inlet of the expansion device, an output signal from said temperature sensor being said value of the fourth temperature; the process includes a step of comparing the speed of the compression device with a maximum threshold speed value, said at least one passing condition including said step of comparing the speed of the compression device; said at least one passing condition includes the condition that a result of the step comparing the speed of the compression device with the maximum speed threshold value is that said speed of the compression device is less than the maximum speed threshold value; the process includes a holding step maintaining the speed of the compression device and the degree of opening of the expansion member; the process applies the holding step when at least one of the said at least one condition for switching to the thermal power maximization mode, other than the condition of exceeding or reaching the maximum threshold value by said quantity representing the high pressure, is not obtained; The process includes a mode for optimizing the consumption of the compression device, the transition to said mode comprising a step for controlling the degree of opening of the expansion member and a step for controlling the speed of the compression device, the transition to said consumption optimization method being carried out under at least one first condition of passage in said consumption optimization method, said at least one first condition of passage in said optimization method including that the value of the quantity representing the high pressure is less than the maximum threshold pressure value; the process includes a step of calculating a setpoint subcooling from the value of the second temperature Te of condensation of the refrigerant, from the value of the third temperature Te of the first heat transfer fluid upstream of the first heat exchanger, and from a second coefficient B such that [Tsbc = B x (Tc-Te)], the second coefficient B preferably having a value between 0.68 and 1; the process includes a step of controlling the degree of opening of the expansion device allowing regulation of the subcooling at the outlet of the first heat exchanger by controlling the degree of opening of the expansion device so that the subcooling value is between the setpoint subcooling value - [3 and the setpoint subcooling value + [3, with [3 being a constant whose value is preferably between 0.2°C and 1°C, the degree of opening of the expansion device increasing when the subcooling value is greater than the setpoint subcooling value + [3, and decreasing when the subcooling value is less than the setpoint subcooling value - [3; in a heating mode, maximizing thermal power is maximizing the heating power of the first heat transfer fluid in the first heat exchanger; the process includes a step of determining the eighth temperature value of the first heat transfer fluid downstream of the first heat exchanger; the circuit includes a temperature sensor for measuring the eighth temperature of the first heat transfer fluid downstream of the first heat exchanger, an output signal from said temperature sensor being said eighth temperature value; the process includes a step of comparing the value of the eighth air temperature downstream of the first heat exchanger and a heating setpoint temperature value, said at least one condition of switching to the heating power maximization mode including said temperature value comparison step; said at least one condition for switching to the heating power maximization mode includes the condition that a result of the step comparing the value of the eighth temperature with the heating setpoint temperature value is that the value of the eighth temperature of the first heat transfer fluid at the outlet of the first heat exchanger is less than the heating setpoint temperature value - a, with a being a constant having as its preferred value a value between 0.2°C and 1°C; the process includes an alternative step of increasing the speed of the compression device in the mode of maximizing heating power; the increase in the speed of the compression device in the alternative step of increasing the speed of the compression device in the heating power maximization mode is controlled such that the value of the eighth temperature of the first heat transfer fluid at the outlet of the first heat exchanger is between the value of the heating setpoint temperature - a and the value of the heating setpoint temperature + a, with a being a constant having as its preferred value a value between 0.2°C and 1°C, the process controlling the increase in the speed of the compression device when the value of the eighth temperature of the first heat transfer fluid is less than the value of the heating setpoint temperature - a,the process controlling the reduction of the speed of the compression device when the value of the eighth temperature of the first heat transfer fluid is greater than the heating setpoint temperature value + a; , the circuit includes an additional electric heating device heating the second heat transfer fluid upstream of the second heat exchanger; the process comprising, in the mode of maximizing heating power, a step of increasing the power of the additional electric heating device; The increase in power of the auxiliary electric heating device in the power increase stage of the auxiliary electric heating device is controlled such that the value of the eighth temperature of the first heat transfer fluid at the outlet of the first heat exchanger is between the heating setpoint temperature value - a and the heating setpoint temperature value + a, where a is a constant whose preferred value is a value between 0.2°C and 1°C, the process controlling the increase in power of the additional electric heating device when the value of the eighth temperature of the first heat transfer fluid is less than the value of the heating setpoint temperature - a, the process controlling the decrease in power (Pwr) of the additional electric heating device when the value of the eighth temperature of the first heat transfer fluid is greater than the value of the heating setpoint temperature + a; • the process includes an alternative mode for optimizing the consumption of the compression device, the transition to said alternative mode for optimizing consumption includes an alternative step for controlling the degree of opening of the expansion member and an alternative step for controlling the speed of the compression device, the transition to said alternative mode for optimizing consumption being carried out under at least a first condition for transitioning to said alternative mode for optimizing consumption, said at least a first condition for transitioning to said optimization mode including that the value of the quantity representing the high pressure is less than the maximum threshold pressure value; • the process includes a step of calculating a second setpoint subcooling from the value of the second temperature Te of condensation of the refrigerant, from the value of the third temperature Te of the first heat transfer fluid upstream of the first heat exchanger, and from a third coefficient C such that [Tsbc2 = C x (Tc-Te)], the third coefficient C having a value between 0.3 and 0.5, and preferably a value equal to 0.35; • The alternative step of controlling the degree of opening of the expansion device allows for the regulation of subcooling at the outlet of the first heat exchanger by controlling the degree of opening of the expansion device so that the subcooling value is between the second subcooling setpoint value - [3 and the second subcooling setpoint value + [3, with [3 being a constant whose value is preferably between 0.2°C and 1°C, the degree of opening of the expansion device increasing when the subcooling value is greater than the second subcooling setpoint value + [3, and decreasing when the subcooling value is less than the second subcooling setpoint value - [3. Brief description of the drawings

[0009] Other features, details and advantages of the invention will become clearer upon reading the following description, which is given by way of illustration only, in conjunction with drawings in which:

[0010] [Fig. 1] is a schematic view of a first refrigerant fluid circuit to which a process according to the invention is applied,

[0011] [Fig.2] is a flowchart describing an implementation of the process according to a first aspect of the invention,

[0012] [Fig.3] is a flowchart describing an implementation of the process according to a second aspect of the invention,

[0013] [Fig.4] is a schematic view of a second refrigerant circuit to which the process according to the invention is applied,

[0014] [Fig. 5] is a schematic view of a third refrigerant circuit to which the process according to the invention is applied,

[0015] [Fig.6] is a flowchart describing an implementation of the process according to a third aspect of the invention,

[0016] [Fig.7] is a flowchart describing an implementation of the process according to a fourth aspect of the invention,

[0017] [Fig.8] is a schematic view of a fourth refrigerant circuit to which the process according to the invention is applied,

[0018] [Fig.9] is a schematic view of a fifth refrigerant fluid circuit to which the process according to the invention is applied. Description of the implementation methods

[0019] In Figures 1, 4, 5, 8, and 9, solid lines represent the conduits connecting one element of the refrigeration circuit to another. Arrows represent the heat transfer fluid flows through the heat exchangers. A chevron on the refrigeration circuit indicates the direction of refrigerant flow. Dashed lines represent communication between sensors in said circuit and a central control unit containing a program for implementing the method of the invention, as well as communication between controllable elements of the circuit and said central control unit.

[0020] In Figures 2, 3, 6, and 7, a rectangle represents a step in the process that is an action other than a comparison of values. A rhombus represents a process step that is a comparison of values, the result of which determines the choice of the next step. Each rectangle or rhombus shows the step number, as well as the quantities involved in that step. Solid arrows indicate the sequence of steps according to the process.

[0021] It should first be noted that the figures set out the invention in detail for its implementation, said figures being of course able to serve to better define the invention, if necessary.

[0022] The terms upstream and downstream used in the following description refer to the direction of flow of the fluid considered.

[0023] The terms inlet and outlet used in the following description refer to the direction of flow of the fluid considered.

[0024] To differentiate the components, the terms “first”, “second”, etc., are used. These terms are not intended to establish a hierarchy or order among the components. They are used for distinction purposes and may be interchanged without affecting the implementation of the invention. For example, the designation “second” does not necessarily imply the presence of two elements.

[0025] A branch is a portion of a circuit connecting one point of the circuit to another point of the circuit.

[0026] When it is specified that a branch includes a given element, this does not exclude the presence of other elements in that branch.

[0027] A conduit is a portion of a circuit connecting one point of the circuit to another point of the circuit, without elements between these two points.

[0028] The SCT thermal conditioning system comprises a refrigerant circuit 1 and a central control unit UC comprising at least one computer, a memory, and a computer program stored in the memory and configured to implement a process 2. The refrigerant circuit 1 forms a closed circuit in which a refrigerant FR can circulate. The refrigerant circuit 1 is leak-proof when it is in a nominal operating state, i.e., without faults or leaks.

[0029] The SCT thermal conditioning system comprises a flow of a first heat transfer fluid FC1 passing through a first heat exchanger of the refrigerant circuit 1 FR, and a second flow of heat transfer fluid FC2 passing through a second heat exchanger of said circuit. These heat transfer fluids can be, for example, air or a heat transfer liquid.

[0030] Fig. 1 illustrates by way of example a first refrigerant circuit 1 suitable for operating, for example, in a mode for air conditioning a vehicle passenger compartment or for cooling a battery.

[0031] The refrigerant circuit 1 to which the process 2 according to the invention is applied is a closed circuit forming a loop in which the components of the refrigerant circuit 1 are traversed in series by the refrigerant FR.

[0032] The refrigerant circuit 1 comprises a refrigerant compression device 3, a first heat exchanger 4 arranged to be traversed by a flow of first heat transfer fluid FC1 and intended to condense the refrigerant FR, a second heat exchanger 5 arranged to be traversed by a flow of second heat transfer fluid FC2 and intended to evaporate the refrigerant FR, an expansion element 6 with variable section disposed between the first heat exchanger 4 and the second heat exchanger 5, an accumulation device 7 of the refrigerant FR disposed between the first heat exchanger 4 and the compression device 3.

[0033] The compression device 3 takes, for example, the form of an electric compressor, that is, a compressor comprising a compression mechanism, an electric motor, and an electrical control and conversion unit. The compression mechanism of the compression device 3 is rotated by the electric motor, the latter being housed within a compressor casing common to the compression mechanism. In a particular example, the compression device 3 for the refrigerant FR has an inlet 8 and an outlet 9.

[0034] The refrigerant circuit 1 includes a conduit A which connects the outlet 9 of the compression device 3 to the inlet of the first heat exchanger 4.

[0035] In this example, conduit A includes a pressure sensor HP1. This pressure sensor HP1 is configured to come into contact with the refrigerant FR exiting the compression device 3.

[0036] The first heat exchanger 4 is traversed by a flow of first heat transfer fluid FC1 capturing heat from the refrigerant fluid FR passing through said first heat exchanger 4. The first heat exchanger 4 is for example a condenser placed at the front of the vehicle.

[0037] The SCT thermal conditioning system includes a temperature sensor T1, dedicated to measuring the temperature of said first heat transfer fluid flow FC1 upstream of the first heat exchanger 4 from the point of view of the flow of said first heat transfer fluid. In the case where the first heat exchanger 4 is a condenser located at the front of the vehicle, this first heat transfer fluid flow FC1 is an outside air flow passing through the first heat exchanger 4.

[0038] The refrigerant circuit 1 includes a conduit B which connects the outlet of the first heat exchanger 4 to the inlet of the expansion member 6. The expansion member 6 has a variable cross-section.

[0039] In this example, conduit B includes a temperature sensor T2. This temperature sensor T2 is configured to come into contact with the refrigerant FR exiting the first heat exchanger 4.

[0040] The refrigerant circuit 1 includes a conduit C which connects the outlet of the expansion device 6 to the inlet of the second heat exchanger 5.

[0041] The second heat exchanger 5 is traversed by a flow of a second heat transfer fluid FC2, transferring its heat to the refrigerant FR flowing through said second heat exchanger 5. The second heat exchanger 5 is for example an evaporator located in the casing of an unrepresented ventilation, heating and / or air conditioning (commonly called “HVAC”) system of which it is a part.

[0042] The SCT thermal conditioning system includes a temperature sensor T3, dedicated to measuring the temperature of said second heat transfer fluid FC2 downstream of the second heat exchanger 5 from the perspective of the flow of said second heat transfer fluid FC2. This flow is, for example, an indoor airflow intended to be cooled by passing through the second heat exchanger 5, which is then an evaporator located in the casing of a ventilation, heating and / or air conditioning (“HVAC”) system (not shown) of which it is a part. The indoor airflow is circulated within the casing by means of an indoor airflow excitation device. The indoor airflow excitation device is, for example, a propeller rotated by an electric motor.

[0043] Circuit 1 includes a conduit D which connects the outlet of the second heat exchanger 5 to the inlet of the refrigerant fluid accumulation device 7 FR.

[0044] The circuit 1 includes a conduit E which connects the outlet of the refrigerant fluid accumulation device 7 to the inlet 8 of the refrigerant fluid compression device 3.

[0045] The SCT thermal conditioning system includes electrical cables 10 connecting the central control unit UC, intended to implement the process 2 according to the invention, to various components of said SCT thermal conditioning system. The central control unit UC is thus connected to the pressure sensor HP1 downstream of the compression device 3, to the temperature sensor T1 of the first heat transfer fluid FC1 upstream of the first heat exchanger 4, to the temperature sensor T2 of the refrigerant FR at the outlet of the heat exchanger 4, and to the temperature sensor T3 of the second heat transfer fluid FC2 downstream of the second heat exchanger 5.

[0046] The process 2 is applicable within a heat transfer fluid cooling mode and / or within a heat transfer fluid heating mode according to the mode being executed by the program configured to implement said process, with steps of said process 2 adapted to said mode.

[0047] Method 2 according to one aspect of the invention performs a first comparison between a value of a quantity representative of a high pressure HP of the refrigerant FR at the outlet of the compression device 3 and a maximum threshold pressure value HPmax. Said method 2 performs a second comparison between a value of a first temperature Tsfc2 of the second heat transfer fluid FC2 downstream of the heat exchanger 5 and a cooling setpoint temperature value Tsfc2c. Said method performs a third comparison between the velocity Ncpr of the Compression device 3 and a maximum speed threshold value Ncpr_max of compression device 3 stored in the memory of the central control unit (CCU) and dependent on ambient conditions. Process 2 checks whether the result of these comparisons corresponds to certain conditions for switching to a thermal power maximization mode. The thermal power maximization mode is a cooling power maximization mode when the program configured to implement process 2 executes process 2 in a heat transfer fluid cooling mode. The thermal power maximization mode is a heating power maximization mode when the program configured to implement process 2 executes process 2 in a heat transfer fluid heating mode.

[0048] Said thermal power being in this example a cooling power of the second heat transfer fluid FC2 in the second heat exchanger 5. Said passage conditions including at least. • the value of the representative quantity of the high pressure HP of the refrigerant FR is equal to or greater than the maximum threshold value of pressure HPmax; • the first temperature value Tsfc2 is strictly greater than the cooling setpoint temperature value Tsfc2c +a, with a being a constant whose value is between 0.2°C and 1°C; • the speed Ncpr of the compression device 3 is less than the maximum threshold value of speed Ncpr_max.

[0049] When the passage conditions are met, the process 2 carries out a step of opening the degree of opening DO of the expansion member and a step of increasing the speed Ncpr of the compression device 3.

[0050] The implementation of process 2 allows the thermodynamic cycle of circuit 1 to be regulated by adjusting the expansion of the refrigerant FR, an expansion performed by the expansion valve 6. An appropriate expansion allows the high pressure HP to be reached, equal to a pressure setpoint HPc at the outlet of the compression device 3. This pressure setpoint HPc is less than or equal to the maximum pressure threshold HPmax, which represents, for example, the maximum permissible operating pressure at the outlet of the compression device 3 as defined by the central control unit UC. This adjustment of the opening by the expansion valve 6 maximizes the achievable cooling capacity by allowing the compression device to increase its speed Ncpr while respecting the maximum permissible pressure threshold HPmax.

[0051] High pressure refers to the pressure level of the refrigerant FR located between the outlet 9 of the compression device 3 and the inlet of the expansion device 6. low pressure means the pressure level of the refrigerant FR located between the outlet of the expansion device 6 and the inlet 8 of the compression device 3.

[0052] In the refrigerant circuit 1, the low-pressure refrigerant FR entering the compression device 3 through inlet 8 of said compression device 3 undergoes compression before exiting through outlet 9 of said device with a measured pressure referred to as high pressure HP. This high pressure HP is measured at the pressure sensor HP1 within the conduit A at the outlet of the compression device 3. Alternatively, it is measured by means of a pressure sensor (not shown) located at the outlet of the first heat exchanger 4. An output signal from said pressure sensor HP1 is the value of the quantity representing the high pressure HP.It is via the electrical cables 10 that the control unit UC controls the degree of opening DO of the expansion member 6, also controls the speed of the compression device 3, and receives the data obtained by all of said pressure and temperature sensors HP1, T1, T2, and T3, and receives the data received by the expansion member 6 and by the compression device 3 following these instructions.

[0053] In this example, the central control unit UC is capable of converting the value of the representative quantity of the high pressure HP of the refrigerant FR measured into a value of a second temperature Te of the condensation of the refrigerant FR. Alternatively, the value of the second temperature Te is directly measured by a temperature sensor (not shown) integrated into the first heat exchanger 4.

[0054] In the first refrigerant circuit 1 shown in [Fig. 1], the refrigerant FR exiting the compression device 3 through outlet 9 of said compression device flows through conduit A and then through the first heat exchanger 4. The first heat exchanger 4 operates as a condenser. It is simultaneously traversed by the flow of the first heat transfer fluid FC1 and by the high-pressure, high-temperature refrigerant FR. Said flow of the first heat transfer fluid FC1 can be, for example, an outside airflow. The outside airflow absorbs heat from the refrigerant FR. A third temperature Te of the outside airflow is measured by the temperature sensor T1 on the front of the vehicle. The central control unit UC receives the signal(s) sent by said temperature sensor T1

[0055] In the refrigerant circuit 1 FR shown in [Fig. 1], the refrigerant FR exiting the first heat exchanger 4 passes through the conduit B before entering the expansion valve 6. The expansion valve 6 expands the refrigerant FR. To do this, it partially opens its internal cross-section to a given degree of opening DO. Any change in the degree of opening DO of the internal cross-section of the expansion valve 6 affects the state of the fluid The refrigerant FR circulates throughout the entire refrigerant circuit. This degree of opening DO is defined by process 2, as described in Figures 2, 3, 6, and 7. Instructions for this degree of opening DO are transmitted to the expansion valve 6 via electrical cables 10 connecting it to the central control unit UC. As it passes through the expansion valve 6, the refrigerant FR changes from high pressure to low pressure. When process 2 is implemented, it controls the degree of opening DO of the expansion valve 6 to achieve a setpoint pressure HPc of the refrigerant FR at the outlet of the compression device 3.

[0056] In the refrigerant circuit 1 shown in [Fig. 1], the low-pressure refrigerant FR exiting the expansion valve 6 flows through the conduit C and then through the second heat exchanger 5. In the operating mode described in [Fig. 1], the second heat exchanger 5 functions as an evaporator. It cools the flow of the second heat transfer fluid FC2 using the refrigerant FR, with which it undergoes heat exchange. This flow is, for example, an indoor airflow intended to be cooled by passing through the second heat exchanger 5, which is, for example, an evaporator located in the casing of a ventilation, heating, and / or air conditioning (“HVAC”) system (not shown), of which it is a part.Thus, when the indoor airflow, driven by a movement device, enters the housing of the ventilation, heating and / or air conditioning (“HVAC”) system, it transfers its heat to the refrigerant FR flowing through the second heat exchanger 5.

[0057] In the first refrigerant circuit 1 shown in [Fig.1], downstream of the second heat exchanger 5, the refrigerant FR passes through the accumulation device 7 before completing its thermodynamic cycle by joining the inlet 8 of the compression device 3.

[0058] Fig. 2 is a flowchart illustrating the steps of process 2 according to a first aspect of the invention leading to a mode of maximizing the cooling power of the second heat transfer fluid FC2 in the second heat exchanger 5.

[0059] The process 2 is implemented following measurements taken at various points in the refrigerant circuit 1 FR. The central control unit UC receives the data from the sensors following these measurements, and provides, for example, instructions relating to these measurements.

[0060] By way of example, different sensors used are described below, as well as the corresponding generated signals.

[0061] The HP1 pressure sensor measures the high pressure HP of the refrigerant at the outlet of the compression device 3. An output signal from said HP1 sensor is said value of the quantity representative of the high pressure HP at the outlet of the compression device 3. Said signal is sent to the central control unit UC.

[0062] The central control unit UC is capable of converting the value of the representative quantity of the high pressure HP of the refrigerant FR measured into the value data of the second condensation temperature Te of the refrigerant FR.

[0063] Alternatively, the SCT thermal conditioning system includes a sensor (not shown) which measures the second condensation temperature Te of the refrigerant FR in the first heat exchanger 4. An output signal from said sensor is said value of the second condensation temperature Te in the first heat exchanger 4. Said signal is sent to the central control unit UC via cables 10.

[0064] The temperature sensor Tl measures the third temperature Te of the first heat transfer fluid FC1 upstream of the first heat exchanger 4. In this example, the first heat transfer fluid FC1 is air. An output signal from said temperature sensor Tl is said value of the third temperature Te of the air upstream of the first heat exchanger 4. Said signal is sent to the central control unit UC via cables 10.

[0065] The temperature sensor T2 measures a fourth temperature Tscd of the refrigerant FR at the outlet of the first heat exchanger 4. An output signal from said sensor T2 is said value of the fourth temperature Tscd at the outlet of the first heat exchanger 4. Said signal is sent to the central control unit UC by cables 10.

[0066] The temperature sensor T3 measures the first temperature Tsfc2 of the second heat transfer fluid FC2 downstream of the second heat exchanger 5. In this example, the second heat transfer fluid FC2 is air. An output signal from said temperature sensor T3 is said value of the first temperature Tsfc2 of the air downstream of the second heat exchanger 5. Said signal is sent to the central control unit UC via cables 10.

[0067] The process 2 includes a holding step E0 which maintains the current velocity Ncpr of the compression device 3 and the current degree of opening DO of the expansion member 6.

[0068] The process 2 includes a step El of determining the value of the quantity representative of the high pressure HP at the outlet of the compression device 3.

[0069] The process 2 includes a step E2 of comparison between the value of the quantity representing the high pressure HP and the maximum threshold value of pressure HPmax recorded in the memory of the central control unit UC.

[0070] A result of the comparison in step E2 between the value of the representative high-pressure quantity HP and the maximum pressure threshold value HPmax, showing that the value of the representative high-pressure quantity HP is equal to or greater than the maximum pressure threshold value HPmax, leads to The next preliminary steps before potentially switching to cooling power maximization mode are: • a step E3 of determining the value of the first temperature Tsfc2 of the air downstream of the second heat exchanger 5; • a step E4 of determining the value of the second condensation temperature Te of the refrigerant FR in the first heat exchanger 4 from the representative value of the high pressure HP of the refrigerant FR; • a step E5 of determining the value of the third temperature Te of the air upstream of the first heat exchanger 4; • a step E6 of determining the value of the fourth temperature Tscd of the refrigerant fluid FR at the outlet of the first heat exchanger 4; • a step El 1 of comparison between the speed Ncpr of the compression device 3 and the maximum threshold value of speed Ncpr_max.

[0071] The said preliminary steps to a possible switch to cooling power maximization mode are carried out without preferential order.

[0072] The process 2 includes a step E7 of calculating a minimum threshold subcooling Tsb_min of the refrigerant FR at the outlet of the first heat exchanger 4. This minimum threshold subcooling Tsb_min is calculated from the value of the third temperature Te of the air upstream of the first heat exchanger 4, the value of the second condensation temperature Te, and a first coefficient A such that [Tsb_min = Ax(Tc - Te)], the first coefficient A having a value between 0.3 and 0.5 and preferably equal to 0.4.

[0073] The process 2 includes a step E8 of calculating the subcooling Tsb of the refrigerant FR at the outlet of the first heat exchanger 4. This subcooling Tsb is calculated from the value of the fourth temperature Tscd of the refrigerant FR at the outlet of the first heat exchanger 4 and the value of the second condensation temperature Te such that [Tsb = Te - Tscd].

[0074] Steps E7 for calculating a minimum threshold subcooling Tsb_min of the refrigerant FR and E8 for calculating the subcooling Tsb of the refrigerant FR are carried out without preferential order.

[0075] The process 2 includes a step E9 of comparison between the value of the first temperature Tsfc2 of the air downstream of the second heat exchanger 5 and the value of the cooling setpoint temperature Tsfc2c recorded in the memory of the central control unit UC.

[0076] A result of the comparison in step E9 between the value of the first temperature Tsfc2 of the air downstream of the second heat exchanger 5 and the cooling setpoint temperature value Tsfc2c showing the value of the The first temperature Tsfc2 between the cooling setpoint temperature value Tsfc2c - a and the cooling setpoint temperature value Tsfc2c + a leads to the transition to the maintenance stage EO, with a being a constant preferably having a value between 0.2°C and 1°C.

[0077] A result of the comparison of step E9 of comparison between the value of the first temperature Tsfc2 of the air downstream of the second heat exchanger 5 and the value of the cooling setpoint temperature Tsfc2c showing the value of the first temperature Tsfc2 strictly greater than the value of the cooling setpoint temperature Tsfc2c + a is a necessary condition for the transition to a step E12 of increasing the degree of opening DO of the expansion member 6.

[0078] The process 2 includes a step E10 of comparison between the value of the subcooling Tsb and the minimum threshold value of subcooling Tsb_min.

[0079] A result of the comparison of step E10 of comparison between the value of the subcooling Tsb and the minimum threshold value of subcooling Tsb_min showing that said value of subcooling Tsb is less than or equal to the minimum threshold value of subcooling Tsb_min leads to the holding step E0.

[0080] A result of the comparison of step E10 of comparison between the value of the subcooling Tsb and the minimum threshold value of subcooling Tsb_min showing the value of subcooling Tsb strictly greater than the minimum threshold value of subcooling Tsb_min is a necessary condition for passing to a step E12 of increasing the degree of opening DO of the expansion member 6.

[0081] The process 2 includes a step El 1 of comparison between the speed Ncpr of the compression device 3 and the maximum threshold value of speed Ncpr_max.

[0082] A result of the comparison of the El 1 step of comparison between the speed Ncpr of the compression device and the maximum threshold value of speed Ncpr_max showing the speed Ncpr equal to the maximum threshold value of speed Ncpr_max leads to the transition to the holding step E0.

[0083] A result of the comparison of step El 1 of comparison between the velocity Ncpr of the compression device and the maximum threshold value of velocity Ncpr_max showing a velocity Ncpr strictly less than Ncpr_max is a necessary condition for the transition to a step E12 of increasing the degree of opening DO of the expansion member 6.

[0084] Step E9 compares the value of the first temperature Tsfc2 of the air downstream of the second heat exchanger 5 and the cooling setpoint temperature value Tsfc2c, and step E10 compares the subcooling value Tsb and the minimum subcooling threshold value Tsb min. Step El 1 of comparison between the speed Ncpr of the compression device and the maximum threshold value of speed Ncpr_max are carried out without preferential order.

[0085] The following conditions must be met to proceed to step E12 of increasing the degree of opening DO of the release member 6:

[0086] The result of the comparison of step El 1 of comparison between the speed Ncpr of the compression device 3 and the maximum threshold value of speed Ncpr_max shows a speed Ncpr strictly less than Ncpr_max.

[0087] The result of the comparison in step E9 between the value of the first temperature Tsfc2 of the air downstream of the second heat exchanger 5 and the value of the cooling setpoint temperature Tsfc2c shows the value of the first temperature Tsfc2 strictly greater than the value of the cooling setpoint temperature Tsfc2c + a, a being a constant between 0.2°C and 1°C.

[0088] The result of the comparison in step E10 between the subcooling value Tsb and the minimum subcooling threshold value Tsb_min shows the subcooling value Tsb strictly greater than the minimum subcooling threshold value Tsb_min.

[0089] Step E12 of increasing the degree of opening DO of the expansion valve 6 is a step in which the degree of opening DO is controlled by the central control unit UC with the aim of obtaining a value of the representative high-pressure quantity HP equal to the pressure setpoint value HPc by means of said increase in the degree of opening DO. Said pressure setpoint value HPc is stored in the memory of the control unit and its value is less than or equal to the maximum pressure threshold value HPmax.

[0090] Following step E12 of increasing the degree of opening DO of the expansion member 6, the process 2 includes a step E13 of increasing the speed Ncpr of the compression device 3 in which the central control unit UC increases the speed Ncpr of the compression device 3 so that the value of the first temperature Tsfc2 downstream of the second heat exchanger 5 is between the setpoint temperature value Tsfc2c - a and the setpoint temperature value Tsfc2c + a, a being a constant between 0.2°C and 1°C.The control unit UC increases the speed Ncpr of the compression device 3 when the value of the first temperature Tsfc2 downstream of the second heat exchanger 5 is greater than the cooling setpoint temperature value Tsfc2c + a, and commands the decrease of the speed Ncpr of the compression device 3 when the value of the first temperature Tsfc2 downstream of the second heat exchanger 5 is less than the cooling setpoint temperature value Tsfc2c - a.

[0091] When the refrigerant FR circulates in the refrigerant circuit 1, the pressure of this refrigerant FR upstream of the expansion valve 6 is lower as the cross-section of the expansion valve 6 is increased. Method 2 will reduce the high pressure HP by increasing the degree of opening DO of the expansion valve 6, thus allowing the compression device 3 a further margin for increasing the velocity Ncpr of said device, and therefore increasing the cooling performance, before reaching the maximum threshold pressure HPmax again.

[0092] Fig. 3 is a flowchart illustrating the steps of process 2 according to a second aspect of the invention leading to a mode of optimization of the consumption of the compression device 3, in an operation of the circuit 1 dedicated to the cooling of the second heat transfer fluid FC2.

[0093] The process 2 includes the step El of determining the value of the quantity representative of the high pressure HP at the outlet of the compression device 3.

[0094] The process 2 includes the step E2 of comparison between the value of the quantity representing the high pressure HP and the maximum threshold value of pressure HPmax recorded in the memory of the central control unit UC.

[0095] A result of the comparison in step E2 between the value of the representative quantity of the high pressure HP and the maximum threshold value of pressure HPmax showing that the value of the representative quantity of the high pressure HP is less than the maximum threshold value of pressure HPmax leads to the following preliminary steps to the mode of optimizing the consumption of the compression device 3: • step E3 of determining the value of the first temperature Tsfc2 of the air downstream of the second heat exchanger 5; • step E4 of determining the value of the second condensation temperature Te of the refrigerant in the first heat exchanger 4 from the value of the representative quantity of the high pressure HP of the refrigerant FR; • step E5 of determining the value of the third temperature Te of the air upstream of the first heat exchanger 4; • step E6 of determining the value of the fourth temperature Tscd of the refrigerant FR at the outlet of the first heat exchanger 4.

[0096] The said preliminary steps to the mode of optimizing the consumption of the compression device 3 are carried out without preferential order.

[0097] The process 2 includes a step E15 for controlling the speed Ncpr of the compression device 3 in which the central control unit UC controls the speed Ncpr of the compression device 3 so that the first temperature value The value of the first temperature Tsfc2 of the air downstream of the second heat exchanger 5 is between the value of the cooling setpoint temperature Tsfc2c - a and the value of the cooling setpoint temperature Tsfc2c + a. The control unit UC increases the speed Ncpr of the compression device 3 when the value of the first temperature Tsfc2 of the air downstream of the second heat exchanger 5 is greater than the value of the cooling setpoint temperature Tsfc2c + a, and commands the decrease of the speed Ncpr of the compression device 3 when the value of the first temperature Tsfc2 of the air downstream of the second heat exchanger 5 is less than the value of the cooling setpoint temperature Tsfc2c - a.

[0098] The process 2 includes a step E7' of calculating a setpoint subcooling Tsbc of the refrigerant FR at the outlet of the first heat exchanger 4. This setpoint subcooling Tsbc is calculated from the value of the third temperature Te of the air upstream of the first heat exchanger 4, the value of the second condensation temperature Te, and a second coefficient B such that [Tsbc = Bx(Tc - Te)], the second coefficient B having as its preferred value a value between 0.68 and 1.

[0099] The process 2 includes the step E8 of calculating the subcooling Tsb of the refrigerant FR at the outlet of the first heat exchanger 4. This subcooling Tsb is calculated from the value of the fourth temperature Tscd of the refrigerant FR at the outlet of the first heat exchanger 4 and the value of the second condensation temperature Te such that [Tsb = Te - Tscd].

[0100] Step E7' of calculating a setpoint subcooling Tsbc of the refrigerant FR and step E8 of calculating the subcooling Tsb of the refrigerant FR are carried out without preferential order.

[0101] The process 2 includes a step E14 for controlling the degree of opening DO of the expansion member 6 allowing regulation of the subcooling Tsb at the outlet of the first heat exchanger 4 in which the central control unit UC controls the degree of opening DO of the expansion member 6 so that the value of subcooling Tsb is between the setpoint subcooling value Tsbc - [3 and the setpoint subcooling value Tsbc + [3, with [3 being a constant whose value is preferably between 0.2 °C and 1 °C. The central control unit UC commands the increase in the degree of opening DO of the expansion member 6 when the subcooling value Tsb is greater than the setpoint subcooling value Tsbc + [3, and commands the decrease in the degree of opening DO when the subcooling value Tsb is less than the setpoint subcooling value Tsbc - [3.

[0102] Fig. 4 illustrates, by way of example, a second refrigerant circuit in which the expansion member 6 and the compression device 3 are controlled according to the steps of process 2 described in Figures 2 and 3.

[0103] Said second refrigerant circuit 1 differs from the first refrigerant circuit 1 illustrated in [Fig. 1] in that it includes an additional branch. Said branch includes a sixth conduit F, a second expansion device 11, a seventh conduit G, a third heat exchanger 12 and an eighth conduit H.

[0104] The conduit B of the second circuit includes a separation point 13 located between the outlet of the first heat exchanger 4 and the inlet of the first expansion device 6.

[0105] Conduit F connects the separation point 13 to the inlet of the second expansion member 11.

[0106] Conduit G connects the outlet of the second expansion member 11 to the inlet of the third heat exchanger 12.

[0107] The third heat exchanger 12 is here a refrigerant fluid evaporator FR through which a flow of a third heat transfer fluid FC3 passes, transferring its heat to the refrigerant fluid FR passing through said exchanger 12. The third heat exchanger 12 is, for example, an evaporator located in the under-hood environment which cools a heat transfer fluid intended to cool a vehicle battery.

[0108] The conduit D of the second circuit includes a junction point 14 located between the outlet of the second heat exchanger 5 and the inlet of the refrigerant fluid accumulation device 7 FR.

[0109] Conduit H connects the outlet of the third heat exchanger 12 to the junction point 14.

[0110] The second circuit includes a temperature sensor T4 for measuring a fifth temperature Tsfc3 of the third heat transfer fluid FC3 downstream of the third heat exchanger 12 from the perspective of the heat transfer fluid FC3 flow. In this example, the third heat transfer fluid FC3 is a heat transfer liquid. An output signal from said temperature sensor T4 is said fifth temperature value Tsfc3 of the third heat transfer fluid FC3 downstream of the third heat exchanger 12. Said signal is sent to the central control unit UC via cables 10.

[0111] At the separation point 13 of the second circuit illustrated in [Fig. 4], the The refrigerant flow FR travels, in whole or in part, through conduit B to the inlet of the first expansion valve 6. The portion of the refrigerant flow FR not destined for the inlet of the first expansion valve 6 travels through conduit F to the inlet of the second expansion valve 11. The degree of opening DO of the first expansion valve 6 and a degree DO' of opening of the second expansion valve 11 determine the amount of refrigerant flow FR passing through each branch of circuit 1. The central control unit UC manages this. The opening degrees DO and DO' of the first and second expansion valves 6 and 11. In each of the first and second expansion valves 6 and 11, the refrigerant flow FR undergoes expansion and changes from high pressure to low pressure. The portion of the refrigerant flow exiting the first expansion valve 6 enters the inlet of the second heat exchanger 5 and passes through said second heat exchanger 5 to evaporate, receiving heat from the heat transfer fluid FC2. In one application example, the heat transfer fluid FC2 is an internal airflow towards the passenger compartment, intended to be cooled through the second heat exchanger 5, which operates as an evaporator. The portion of the refrigerant flow FR exiting the second expansion valve 11 enters the inlet of the third heat exchanger 12 and passes through said third heat exchanger 12 to evaporate, receiving heat from the heat transfer fluid FC3.In this application example, the heat transfer fluid flow FC3 is a heat transfer fluid flow intended to cool a vehicle battery. The refrigerant flow FR exiting the third heat exchanger 12 reaches the junction point 14 via the conduit H. The refrigerant flow FR exiting the second heat exchanger 5 reaches the junction point 14 via the portion of conduit D connecting the outlet of the second heat exchanger 5 and the junction point 14. The entire refrigerant flow FR then reaches the inlet of the storage device 7 from the junction point 14.

[0112] According to one aspect of the invention, the steps of process 2 described above concerning the signal of the value of the first temperature Tsfc2 and concerning the expansion member 6 are also respectively applicable to the signal of the value of the fifth temperature Tsfc3 and to the expansion member 11. The choice of controlling the first expansion member 6 or the second expansion member 11 according to process 2 will depend on the choice of the objective of maximizing the cooling power between the flow of the second heat transfer fluid FC2 in the second exchanger 5 and the flow of the third heat transfer fluid FC3 in the third heat exchanger 12.

[0113] In an example of use not shown, the conduit F includes the temperature sensor T2 for measuring the fourth temperature Tscd of the refrigerant FR.

[0114] Fig. 5 illustrates, by way of example, a third circuit 1b of refrigerant FR in which the expansion member 6 and the compression device 3 are controlled according to the steps of process 2 described in Figures 2 and 3.

[0115] This third circuit 1b of refrigerant FR differs from the first circuit 1 of [Fig. 1] in that: • the portion of the circuit between the outlet of the first heat exchanger 4 and the inlet of the second heat exchanger 5 includes additional components; • the refrigerant fluid accumulation device 7 FR is no longer positioned between the outlet of the second heat exchanger 5 and the inlet of the compression device 3 but positioned between the outlet of the first heat exchanger 4 and the inlet of the second heat exchanger 5.

[0116] The third circuit 1b includes a conduit B' connecting the output of the first expansion member 6 to the input of the accumulation device 7.

[0117] The third circuit 1b includes a conduit B” connecting the output of the accumulation device 7 to the input of a third expansion member 15.

[0118] Conduit C of the third circuit 1b connects the outlet of the third expansion member 15 to the inlet of the second heat exchanger 5.

[0119] The conduit D of the third circuit 1b connects the outlet of the second heat exchanger 5 to the inlet 8 of the compression device 3.

[0120] The conduit D of the third circuit 1b includes a temperature sensor T4 dedicated to measuring a sixth temperature Tsev of the refrigerant FR at the outlet of the second heat exchanger 5. An output signal from said sensor T4 is said value of the sixth temperature Tsev of the refrigerant FR at the outlet of the second heat exchanger 5. Said signal is sent to the central control unit UC by cables 10.

[0121] The part of the third circuit 1b between the output 9 of the compression device 3 and the input of the first expansion member 6 is identical to that of the first circuit 1 illustrated in [Fig.1].

[0122] Within the third circuit 1b illustrated in [Fig. 5], the refrigerant flow FR exiting the first heat exchanger 4 enters the first expansion valve 6 via conduit B and undergoes a first expansion as it passes through said first expansion valve 6. The pressure level of the refrigerant FR is at an intermediate level between the high pressure HP upstream of the first expansion valve 6 and the low pressure downstream of the third expansion valve 15. The refrigerant flow FR then enters the refrigerant storage device 7 via conduit B'. The refrigerant flow FR then enters the third expansion valve 15 via conduit B” and undergoes a second expansion as it passes through said third expansion valve 15. The low-pressure refrigerant flow exiting the third expansion valve 15 then enters the inlet of the second heat exchanger 5 via conduit C.

[0123] The central control unit UC controls the degree of opening DO of the first expansion member 6 and a degree of opening DO” of the third expansion member 15.

[0124] In an example of the application of process 2 to the third circuit 1b illustrated in [Fig. 5], process 2 includes an unshown step of regulating a superheat Tsh of refrigerant FR at the outlet of the second heat exchanger 5 by controlling the degree of opening DO” of the third expansion valve 15. The The superheat Tsh is, for example, calculated from the sixth temperature value Tsev and from a seventh temperature value Tev of the evaporation of the refrigerant FR in the second heat exchanger 5, determined beforehand such that [Tsh = Tsev - Tev]. The central control unit UC controls the degree of opening DO” of the third expansion valve 15 so that the superheat value Tsh is between a setpoint superheat value Tshc - y and the setpoint superheat value Tshc + y, where y is a constant whose value is preferably between 0.2°C and 1°C. The setpoint superheat value Tshc is stored in the memory of the central control unit UC.The central control unit UC commands the increase of the degree of opening DO” of the third expansion member 15 when the superheat value Tsh is greater than the setpoint superheat value Tshc + y, and commands the decrease of said degree of opening DO” when the superheat value Tsh is less than the setpoint superheat value Tshc - y. .

[0125] Figure 6 is a flowchart illustrating the steps of process 2 according to a third aspect of the invention leading to a method of maximizing the heating power of the first heat transfer fluid FC1 in the first heat exchanger 4. This third aspect of the invention differs from the first aspect of the invention illustrated in Figure 2 in that, within process 2: • Step E3 of determining the value of the first temperature Tsfc2 of the second heat transfer fluid FC2 downstream of the second heat exchanger 5 is replaced by a step E3' of determining the value of the eighth temperature Tsfcl of the first heat transfer fluid FC1 downstream of the first heat exchanger 4; • Step E9, comparing the value of the first temperature Tsfc2 of the second heat transfer fluid FC2 downstream of the second heat exchanger 5 and the cooling setpoint temperature value Tsfc2c, is replaced by a step E9' comparing the value of the eighth temperature Tsfcl of the first heat transfer fluid FC1 downstream of the first heat exchanger 4 and a heating setpoint temperature value Tsfclc.A result of the comparison of said step E9” of comparison between the value of the eighth temperature Tsfcl of the first heat transfer fluid FC1 downstream of the first heat exchanger 4 and the value of the heating setpoint temperature Tsfclc showing a value of the eighth temperature Tsfcl between the value of the heating setpoint temperature Tsfclc - a and the value of the heating setpoint temperature Tsfcl + a leads to the transition to the holding step E0, with a which is a constant having a value preferably between 0.2°C and 1°C; . the following condition is necessary for the transition to step E12 of increasing the degree of opening DO of the expansion member 6: the result of the comparison of said step E9' of comparison between the value of the eighth temperature Tsfcl first heat transfer fluid FC1 downstream of the first heat exchanger 4 and the value of the heating setpoint temperature Tsfclc shows that the value of the eighth temperature Tsfcl strictly is less than the value of the heating setpoint temperature Tsfclc - a; Step E13 of increasing the speed Ncpr of the compression device 3 is replaced by an alternative step E13' of increasing the speed Ncpr of the compression device 3 in which the central control unit UC increases the speed Ncpr of the compression device 3 so that the value of the eighth temperature Tsfcl downstream of the first heat exchanger 4 is between the heating setpoint temperature value Tsfclc - a and the heating setpoint temperature value Tsfclc + a, a being a constant whose value is preferably between 0.2°C and 1°C, the control unit UC increasing the speed Ncpr of the compression device 3 when the value of the eighth temperature Tsfcl downstream of the first heat exchanger 4 is less than the heating setpoint temperature value Tsfclc - a,and decreasing the speed Ncpr of the compression device 3 when the value of the eighth temperature Tsfcl downstream of the first heat exchanger 4 is greater than the heating setpoint temperature value Tsfcc + a ; , a step E16 of increasing the power Pwr of an additional electric heating device 16 is added, in which the central control unit UC increases the power Pwr of the additional electric heating device 16 for heating the second heat transfer fluid FC2 upstream of the second heat exchanger 5, so that the value of the eighth temperature Tsfcl downstream of the first heat exchanger 4 is between the heating setpoint temperature value Tsfclc - a and the heating setpoint temperature value Tsfclc + a, a being a constant whose value is preferably between 0.2°C and 1°C, the control unit UC increasing the power Pwr of the additional electric heating device 16 when the value of the eighth temperature Tsfcl downstream of the first heat exchanger 4 is less than the heating setpoint temperature value Tsfclc - a,and decreasing the power Pwr of the additional electric heating device 16 when the value of the eighth temperature Tsfcl downstream of the first heat exchanger 4 is greater than the temperature value of , heating setpoint Tsfcc + a. Said step E14 of increasing the power Pwr of the additional electric heating device 16 is of particular interest for reaching the heating setpoint temperature Tsfclc when for example the speed Ncpr of the compression device 3 has already reached the maximum threshold value of speed Ncpr_max; • Step El 1, comparing the speed Ncpr of the compression device 3 with the maximum threshold speed Ncpr_max, is removed. The condition for proceeding to step E12, which increases the degree of opening DO of the expansion member 6, and which depends on a result of said step El 1 comparing the speed Ncpr of the compression device with the maximum threshold speed Ncpr_max, is therefore removed; • Step E4 of determining the value of the second condensation temperature Te of the refrigerant in the first heat exchanger 4 from the value of the representative quantity of the high pressure HP of the refrigerant FR is removed; • Step E5 of determining the value of the third temperature Te of the first heat transfer fluid FC1 upstream of the first heat exchanger 4 is removed; • Step E6 for determining the value of the fourth temperature Tscd of the refrigerant FR at the outlet of the first heat exchanger 4 is removed; • Step E7 for calculating a minimum threshold subcooling Tsb_min of the refrigerant FR is removed; • Step E8 for calculating the subcooling Tsb of the refrigerant FR is removed; • Step E10, which compares the subcooling value Tsb with the minimum subcooling threshold value Tsb_min, is removed. The condition for proceeding to step E12, which increases the degree of opening DO of the expansion valve 6, and which depends on the result of said step E10 (comparing the subcooling value Tsb with the minimum subcooling threshold value Tsb_min), is removed.

[0126] In an example of application of the third aspect of process 2, the first heat transfer fluid flow FC1 is an internal airflow towards the passenger compartment and intended to be heated through the first heat exchanger 4 which operates as an internal condenser disposed in the casing of an unshown ventilation, heating and / or air conditioning (“HVAC”) system of which it is a part.

[0127] Fig. 7 is a flowchart illustrating the steps of process 2 according to a fourth aspect of the invention, leading to an alternative mode of optimizing the consumption of the compression device 3, in an operation of the circuit 1 dedicated to heating the first heat transfer fluid FC1.

[0128] Said fourth aspect of the invention differs from the second aspect of the invention illustrated in [Fig. 3] in that within process 2: • Step E3 of determining the value of the first temperature Tsfc2 of the second heat transfer fluid downstream of the second heat exchanger 5 is replaced by step E3' of determining the value of the eighth temperature Tsfcl of the first heat transfer fluid FC1 downstream of the first heat exchanger 4; • the step E15 of controlling the speed Ncpr of the compression device 3 is replaced by the alternative step E15' of controlling the speed Ncpr of the compression device 3 in which the central control unit UC controls the speed Ncpr of the compression device 3 so that the value of the eighth temperature Tsfcl of the first heat transfer fluid FC1 downstream of the first heat exchanger 4 is between the value of the heating setpoint temperature Tsfclc - a and the value of the heating setpoint temperature Tsfclc + a, a being a constant preferably between 0.2°C and 1°C; • Step E7' for calculating the setpoint subcooling Tsbc is replaced by a step E7” for calculating a second setpoint subcooling Tsbc2 from the value of the second temperature Te of condensation of the refrigerant FR, from the value of the third temperature (Te) of the first heat transfer fluid FC1 upstream of the first heat exchanger 4, and from a third coefficient C such that [Tsbc2 = C x (Tc-Te)], the third coefficient C having a value between 0.3 and 0.5, and preferably a value equal to 0.35. • Step E14, which controls the degree of opening DO of the expansion valve 6, is replaced by an alternative step E14', also for controlling the degree of opening DO of the expansion valve 6. This alternative step allows for regulation of the subcooling Tsb at the outlet of the first heat exchanger 4. In this alternative step, the central control unit UC controls the degree of opening DO of the expansion valve 6 so that the subcooling value Tsb is between the setpoint value for the second subcooling Tsbc2 - [3] and the setpoint value for the second subcooling Tsbc2 + [3], where [3] is a constant whose value is preferably between 0.2 °C and 1 °C. The central control unit UC controls the increase in the degree of opening DO of the expansion member 6 when the subcooling value Tsb is greater than the second subcooling setpoint value Tsbc2 + [3, and controls the decrease in the degree of opening DO when the subcooling value Tsb is less than the second subcooling setpoint value Tsbc2 - [3.

[0129] Figure 8 illustrates, by way of example, a fourth circuit of refrigerant fluid FR to which the third aspect and the fourth aspect of process 2 of the invention illustrated in figures 6 and 7 are applicable.

[0130] The fourth refrigerant circuit FR differs from the example of the first refrigerant circuit 1 illustrated in [Fig. 1] in that: • the fourth circuit includes a temperature sensor T5 of the first heat transfer fluid FC1 at the outlet of the first heat exchanger 4 dedicated to measuring the eighth temperature Tsfcl of the first heat transfer fluid FC1 at the outlet of the first heat exchanger 4. An output signal from said sensor T5 is said value of the eighth temperature Tsfcl of the first heat transfer fluid FC1 at the outlet of the first heat exchanger 4. Said signal is sent to the central control unit UC by cables 10; • the fourth circuit includes the additional electric heating device 16 heating the second heat transfer fluid FC2 upstream of the second heat exchanger 5. The central control unit UC controls the heating power of said additional electric heating device 16 via cables 10.

[0131] In this embodiment, the first heat transfer fluid FC1 is, for example, an interior airflow intended to be heated by passing through the first heat exchanger 4, which is then an internal condenser located within the casing of an unshown ventilation, heating and / or air conditioning (“HVAC”) system of which it is a part. In the same embodiment, the second heat transfer fluid FC2 is, for example, a heat transfer fluid transferring its heat to the refrigerant FR within the second heat exchanger 5, which is then an evaporator located in the environment under the hood of the vehicle.

[0132] Fig. 9 illustrates, by way of example, a fifth circuit Id of refrigerant FR to which the third aspect and the fourth aspect of the process 2 of the invention illustrated in figures 6 and 7 are applicable.

[0133] The fifth refrigerant circuit Id FR differs from the example of the first refrigerant circuit 1 illustrated in [Fig. 1] in that: • The fifth circuit Id includes the temperature sensor T5 of the first heat transfer fluid FC1 at the outlet of the first heat exchanger 4 dedicated to the measurement of the eighth temperature Tsfcl of the first heat transfer fluid FC1 at the outlet of the first heat exchanger 4. An output signal from said sensor T5 is said value of the eighth temperature Tsfcl of the first heat transfer fluid FC1 at the outlet of the first heat exchanger 4. Said signal is sent to the central control unit UC by cables 10; • The fifth circuit Id includes the additional electric heating device 16 heating the first heat transfer fluid FC1 upstream of the second heat exchanger 5. The central control unit UC controls the heating power of said additional electric heating device 16 via cables 10.

[0134] In this embodiment, the first heat transfer fluid FC1 is, for example, an interior airflow intended to be heated by passing through the first heat exchanger 4, which is then an internal condenser located within the casing of an unshown ventilation, heating and / or air conditioning (“HVAC”) system of which it is a part. In the same embodiment, the second heat transfer fluid FC2 is, for example, a heat transfer fluid transferring its heat to the refrigerant FR within the second heat exchanger 5, which is then an evaporator located in the environment under the hood of the vehicle.

Claims

1. Demands Method (2) for controlling a refrigerant (RF) circuit (1) for a vehicle, said refrigerant (RF) circuit (1) comprising at least one refrigerant (RF) compression device (3), a first heat exchanger (4) arranged to be traversed by a flow of a first heat transfer fluid (FC1) and intended to condense the refrigerant (RF), a second heat exchanger (5) arranged to be traversed by a flow of a second heat transfer fluid (FC2) and intended to evaporate the refrigerant (RF), a variable area expansion device (6) disposed between the first heat exchanger (4) and the second heat exchanger (5), a refrigerant (RF) accumulation device (7) disposed between the first heat exchanger (4) and the compression device (3),the process (2) comprising a step (E1) of determining a value of a quantity representative of a high pressure (HP) of the refrigerant (FR) between the outlet of the compression device (3) and the inlet of the expansion member (6), the process (2) also comprising a step (E2) of comparing between the value of said quantity representative of the high pressure (HP) and a maximum threshold pressure value (HPmax), in which the process comprises a mode for maximizing thermal power, the transition to said mode of maximizing thermal power comprising a step (E12) of increasing the degree of opening (DO) of the expansion member (6) and a step (E13; E13') of increasing the velocity (Ncpr) of the compression device (3), the transition to said mode being carried out under at least one transition condition,said at least one transition condition including exceeding or reaching the maximum pressure threshold value (HPmax) by said high-pressure representative quantity (HP), said maximization of thermal power being, in a heat transfer fluid cooling mode, a maximization of the cooling power of the second heat transfer fluid (FC2) in the second heat exchanger (5), said process (2) comprising preliminary steps to the transition to the cooling power maximization mode, said preliminary steps comprising a step (E4) of determining a second condensation temperature (Te) in the first heat exchanger (4), a step (E5) of, determination of a third temperature (Te) of the first heat transfer fluid (FC1) upstream of the first heat exchanger (4), a step (E7) of calculation of a minimum threshold subcooling (Tsb_min) from the value of the second condensation temperature (Te) of the refrigerant (FR), from the value of the third temperature (Te) of the first heat transfer fluid (FC1) upstream of the first heat exchanger (4), and from a first coefficient (A) such that [Tsb_min = A x (Tc-Te)], the first coefficient (A) having a value between 0.3 and 0.5 and preferably a value equal to 0.4, a step (E6) of determination of the value of a fourth temperature (Tscd) of the refrigerant (FR) between the outlet of the first heat exchanger (4) and the inlet of the expansion device (6),a step (E8) for calculating a subcooling (Tsb) such that said subcooling (Tsb) is equal to the difference between the second condensation temperature (Te) and the fourth temperature (Tscd) of the refrigerant at the outlet of the first heat exchanger (4), i.e. [Tsb=(Tc-Tscd)], and a step (E10) for comparing the value of the subcooling (Tsb) and the minimum subcooling threshold value (Tsb_min), said at least one passing condition including said step (E10) for comparing the value of the subcooling, said at least one passing condition including the condition that a result of the step (E10) for comparing the value of the subcooling (Tsb) and the minimum subcooling threshold value (Tsb_min) is that the value of the subcooling (Tsb) is greater than the minimum subcooling threshold value (Tsb_min).,

2. A control method (2) according to the preceding claim, comprising a step (E3) of determining a first temperature value (Tsfc2) of the second heat transfer fluid (FC2) downstream of the second heat exchanger (5), said method (2) comprising a step (E9) of comparing the first temperature value (Tsfc2) with a cooling setpoint temperature value (Tsfc2c), said at least one pass condition including said step of comparing the first temperature value, said at least one pass condition including the condition that a result of step (E9) of comparing the first temperature value (Tsfc2) with the value of The cooling setpoint temperature (Tsfc2c) is that the value of the first temperature (Tsfc2) of the second heat transfer fluid (FC2) downstream of the second heat exchanger (5) is greater than the cooling setpoint temperature value (Tsfc2c) + a, with a being a constant having a preferred value between 0.2°C and 1°C.

3. A method (2) of control according to any one of the preceding claims, comprising a step (El 1) of comparing the speed (Ncpr) of the compression device (3) with a maximum threshold speed value (Ncpr_max), said at least one passing condition including said step of comparing the speed (Ncpr) of the compression device (3), said at least one passing condition including the condition that a result of the step of comparing (El 1) the speed (Ncpr) of the compression device (3) with the maximum threshold speed value (Ncpr_max) is that said speed (Ncpr) of the compression device (Ncpr) is less than the maximum threshold speed value (Ncpr_max).

4. A control method (2) according to any one of the preceding claims, comprising a holding step (EO) maintaining the speed (Ncpr) of the compression device (3) and the degree of opening (DO) of the expansion member (6), said method (2) applying the holding step (EO) when at least one of said at least one condition for switching to the thermal power maximization mode, other than the condition of exceeding or reaching the maximum pressure threshold value (HPmax) by said high pressure representative quantity (HP), is not obtained.

5. A control method (2) according to any one of the preceding claims, comprising a method for optimizing the consumption of the compression device (3), the transition to said consumption optimization method comprising a step (E14) for controlling the degree of opening (DO) of the expansion member (6) and a step (E15) for controlling the speed (Ncpr) of the compression device (3), the transition to said consumption optimization method being carried out under at least one first condition for transitioning to said consumption optimization method, said at least one first condition for transitioning to said optimization method including that the value of the representative quantity

6. high pressure (HP) is less than the maximum pressure threshold value (HPmax). Method (2) of control according to the preceding claim, comprising preliminary steps to the transition to the consumption optimization mode, said preliminary steps comprising step (E4) of determining the second condensation temperature (Te) in the first heat exchanger (4), step (E5) of determining the third temperature (Te) of the first heat transfer fluid (FC1) upstream of the first heat exchanger (4), a step (E71) of calculating a setpoint subcooling (Tsbc) from the value of the second condensation temperature (Te) of the refrigerant (FR), from the value of the third temperature (Te) of the first heat transfer fluid (FC1) upstream of the first heat exchanger (4), and from a second coefficient (B) such that [Tsbc = B x (Tc-Te)], the second coefficient (B) having as its preferred value a value between 0.68 and 1,step (E6) of determining the value of the fourth temperature (Tscd) of the refrigerant (FR) between the outlet of the first heat exchanger (4) and the inlet of the expansion device (6), and step (E8) of calculating the subcooling (Tsb) such that said subcooling (Tsb) is equal to the difference between the second condensation temperature (Te) and the fourth temperature (Tscd) of the refrigerant at the outlet of the first heat exchanger, i.e. [Tsb=(Tc-Tscd)], said step (E14) of controlling the degree of opening (DO) of the expansion device (6) allowing regulation of the subcooling (Tsb) at the outlet of the first heat exchanger (4) by controlling the degree of opening (DO) of the expansion device (6) so that the value of subcooling (Tsb) is between the setpoint subcooling value (Tsbc) - [3 and the setpoint subcooling value (Tsbc) + [3,with [3 being a constant whose value is preferably between 0.2°C and 1°C, the degree of opening (DO) of the expansion member (6) increases when the subcooling value (Tsb) is greater than the setpoint subcooling value (Tsbc) + [3, and decreases when the subcooling value (Tsb) is less than the setpoint subcooling value (Tsbc) - [3.,

7. A method (2) of control according to claim 1, wherein a second maximization of thermal power, in a heat transfer fluid heating mode, is a maximization of the heating power of the first heat transfer fluid (FC1) in the first heat exchanger (4).

8. A control method (2) according to the preceding claim comprising a step (E3') of determining an eighth temperature value (Tsfcl) of the first heat transfer fluid (FC1) downstream of the first heat exchanger (4), said method 2 comprising a step (E9') of comparing the eighth temperature value (Tsfcl) of the air downstream of the first heat exchanger (4) with a heating setpoint temperature value (Tsfclc), said at least one switching condition in the heating power maximization mode including said step (E9') of comparing the temperature value,said at least one condition for switching to the heating power maximization mode including the condition that a result of step (E9') comparing the value of the eighth temperature (Tsfcl) with a heating setpoint temperature value (Tsfclc) is that the value of the eighth temperature (Tsfcl) of the first heat transfer fluid (FC1) at the outlet of the first heat exchanger (4) is less than the heating setpoint temperature value (Tsfclc) - a, with a being a constant having as its preferred value a value between 0.2°C and 1°C.

9. A method (2) of control according to the preceding claim, wherein the transition to the heating power maximization mode includes an alternative step (E13') of increasing the speed (Ncpr) of the compression device (3) in the heating power maximization mode.

10. A method (2) of control according to the preceding claim, wherein the circuit (1) includes an additional electric heating device (16) heating the second heat transfer fluid (FC2) upstream of the second heat exchanger (5), said method (2) comprising, in the mode of maximizing heating power, a step (E16) of increasing the power (Pwr) of the additional electric heating device (16).

11. A method (2) of control according to any one of claims 7 to 10, comprising an alternative mode of optimization of the

12. consumption of the compression device (3), the transition to said alternative mode comprising an alternative step (El4') of control of the degree of opening (DO) of the expansion member (6) and an alternative step (El5') of control of the speed (Ncpr) of the compression device (3), the transition to said alternative mode of consumption optimization being carried out under at least a first condition of transition to said alternative mode of consumption optimization, said at least a first condition of transition to said optimization mode including that the value of the quantity representing the high pressure (HP) is less than the maximum threshold pressure value (HPmax). Method (2) of control according to the preceding claim, comprising preliminary steps to the switch to the alternative mode of consumption optimization, said steps comprising step (E4) of determining the second condensation temperature (Te) in the first heat exchanger (4), step (E5) of determining the third temperature (Te) of the first heat transfer fluid (FC1) upstream of the first heat exchanger (4), a step (E7”) of calculating a second setpoint subcooling (Tsbc2) from the value of the second condensation temperature (Te) of the refrigerant (FR), from the value of the third temperature (Te) of the first heat transfer fluid (FC1) upstream of the first heat exchanger (4), and from a third coefficient (C) such that [Tsbc2 = C x (Tc-Te)], the third coefficient (C) having a value between 0.3 and 0.5, and preferably a value equal to 0.35,step (E6) of determining the value of the fourth temperature (Tscd) of the refrigerant (FR) between the outlet of the first heat exchanger (4) and the inlet of the expansion device (6), and step (E8) of calculating the subcooling (Tsb) such that said subcooling (Tsb) is equal to the difference between the second condensation temperature (Te) and the fourth temperature (Tscd) of the refrigerant at the outlet of the first heat exchanger, i.e. [Tsb=(Tc-Tscd)], said alternative step (E14') of controlling the degree of opening (DO) of the expansion device (6) allowing regulation of the subcooling (Tsb) at the outlet of the first heat exchanger (4) by controlling the degree of opening (DO) of the expansion device (6) so that the value of sub-, cooling (Tsb) is between the second setpoint subcooling value (Tsbc2) - [3 and the second setpoint subcooling value (Tsbc2) + [3, with [3 being a constant whose value is preferably between 0.2°C and 1°C, the degree of opening (DO) of the expansion member (6) increasing when the subcooling value (Tsb) is greater than the second setpoint subcooling value (Tsbc2) + [3, and decreasing when the subcooling value (Tsb) is less than the second setpoint subcooling value (Tsbc2) - [3.

13. Thermal conditioning system (TCS) comprising a central control unit (CU), said unit comprising at least one computer, a memory and a computer program stored in the memory, the system also comprising a vehicle refrigerant (RF) circuit (1), the refrigerant (RF) circuit (1) comprising at least one refrigerant (RF) compression device (3), a first heat exchanger (4) arranged to be traversed by a flow of a first heat transfer fluid (FC1) and intended to condense the refrigerant (RF), a second heat exchanger (5) arranged to be traversed by a flow of a second heat transfer fluid (FC2) and intended to evaporate the refrigerant (RF), a variable area expansion device (6) disposed between the first heat exchanger (4) and the second heat exchanger (5),a refrigerant fluid (RF) accumulation device (7) disposed between the first heat exchanger (4) and the compression device (3), wherein said computer program is configured to implement the method (2) according to any one of the preceding claims.

14. Computer program comprising instructions that cause the thermal conditioning system according to the preceding claim to perform the steps of the control process according to any one of claims 1 to 14.

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