Method for controlling a thermal conditioning system for a motor vehicle

Abstract

The invention relates to a method for controlling a thermal conditioning system (100) for a motor vehicle, comprising a refrigerant circuit (10) which has: - a main loop (A) comprising, in series: -- a compressor (7), -- a first exchanger (1) thermally coupled with an internal air flow (Fi), -- a second exchanger (2), - a first bypass branch (B), - a second bypass branch (C), comprising a third exchanger (3) thermally coupled with an element (25) of an electric drive train, - a third bypass branch (D) comprising a fourth exchanger (4) which exchanges heat with the internal air flow (Fi), the method comprising the following successive steps: - circulating refrigerant at high pressure in the first exchanger (1), - expanding the refrigerant to an intermediate pressure and circulating it in the third exchanger (3), - expanding the refrigerant to a low pressure and circulating it in the fourth exchanger (4).

Description

Description Title: Method for controlling a thermal conditioning system for a motor vehicle Technical field [1] The present invention relates to the field of thermal conditioning systems. Such systems can, for example, be fitted to motor vehicles. These systems make it possible to ensure thermal regulation of various parts of the vehicle, such as the passenger compartment or an electrical energy storage battery, when the vehicle is electrically powered. Heat exchanges are managed mainly by the compression and expansion of a refrigerant circulating in a circuit in which several heat exchangers are arranged. A compressor delivers the refrigerant in a high-pressure state and allows circulation of the refrigerant in the circuit. Prior art [2] It is known to use carbon dioxide as a refrigerant, which allows to limit to a minimum the global warming potential (GWP coefficient) of the refrigerant used. [3] Various thermal conditioning systems adapted to operate with carbon dioxide as the refrigerant have been proposed. These systems can perform many different functions, depending on the heat exchangers through which the refrigerant can circulate, and depending on the expansion rate provided by each of the expansion devices upstream of these exchangers. Possible modes of operation include cooling the vehicle cabin and heating it, as well as cooling and heating electrical energy storage batteries. [4] In order to further optimize such thermal conditioning systems, it is desirable to optimize the operating modes, as well as their control. Summary [5] For this purpose, a method is proposed for controlling a thermal conditioning system for a motor vehicle. The thermal conditioning system comprises a refrigerant circuit, the refrigerant circuit comprising: - a main loop comprising successively, depending on the direction of circulation of the refrigerant fluid: -- a compressor, -- a first heat exchanger thermally coupled with a first flow of air inside a passenger compartment of the vehicle, -- a first regulator, -- a second regulator, -- a second heat exchanger configured to exchange heat with an air flow outside the vehicle passenger compartment, -- a refrigerant fluid accumulation device, - a first bypass branch connecting a first connection point arranged on the main loop downstream of a compressor outlet and upstream of the first exchanger to a second connection point arranged on the main loop downstream of the second heat exchanger and upstream of the accumulation device, the first bypass branch comprising a third expansion valve, - a second branch connecting a third connection point arranged on the main loop between the first exchanger and the second expander, for example between the first exchanger and the first expander, to a fourth connection point arranged on the main loop downstream of the second exchanger and upstream of the accumulation device, the second branch successively comprising a fourth expander and a third heat exchanger thermally coupled with an element of an electric traction chain of a motor vehicle, - a third branch connecting a fifth connection point arranged on the main loop between the second regulator and the first regulator to a sixth connection point arranged on the main loop between the second connection point and the fourth connection point, the third branch branch successively comprising a fifth expansion valve and a fourth heat exchanger configured to exchange heat with a second interior air flow, - a fourth branch connection connecting a seventh connection point arranged on the second branch connection downstream of the third exchanger and upstream of the fourth connection point to an eighth connection point arranged on the main loop between the fifth connection point and the second regulator, the method comprising the successive steps: (i) provide a high pressure refrigerant flow at the compressor outlet, (ii) circulating high pressure refrigerant fluid through the first heat exchanger, (iii) expanding the high pressure refrigerant from the first heat exchanger to an intermediate pressure lower than the high pressure, (iv) circulating the refrigerant at intermediate pressure in the third exchanger, (v) expanding the refrigerant fluid from the third exchanger to a low pressure lower than the intermediate pressure, (vi) circulate the refrigerant at low pressure in the fourth exchanger. [6] The refrigerant heats the first indoor air flow at the first exchanger and cools the second indoor air flow at the fourth exchanger. The indoor air flow is thus dehumidified. When the total available heating power is greater than the heating power requirement at the first exchanger, the excess heating power must be dissipated at another heat exchanger. According to conventional methods, this excess power is dissipated into the outside air flow at the second exchanger. This thermal power is thus lost. In the proposed method, the exchanger in which the excess heating power is dissipated is the third exchanger, which is thermally coupled to an element of the vehicle's powertrain. The second exchanger does not participate in the heat exchange. The excess heat can thus be used to achieve thermal conditioning of this element of the vehicle's powertrain, which may be, for example, the electrical energy storage battery. The excess heat produced by the thermal conditioning system can be dissipated in the third exchanger, which makes it possible to heat, for example, the battery, when it is cold, typically to a temperature below 15°C. [7] The features listed in the following paragraphs can be implemented independently of each other or in any technically possible combination: [8] The first indoor airflow may be identical to the second indoor airflow. In other words, the airflow forming the first indoor airflow may be equal to the airflow forming the second indoor airflow. [9] The first indoor airflow may be distinct from the second indoor airflow.

[0010] In particular, the air flow rate forming the first interior air flow may be less than the air flow rate forming the second interior air flow. In other words, part of the second interior air flow can bypass the first exchanger.

[0011] The fourth exchanger is arranged upstream of the first exchanger in a flow direction of the second interior air flow.

[0012] The compressor moves the refrigerant fluid from a low pressure state, at the compressor inlet, to a high pressure state, at the compressor outlet.

[0013] According to the proposed method, the first exchanger operates as a refrigerant fluid cooler.

[0014] According to an exemplary embodiment, the first heat exchanger is configured to exchange heat with the first air flow inside the passenger compartment of the vehicle.

[0015] According to an alternative embodiment, the first heat exchanger is configured to exchange heat with a heat transfer liquid circulating in a closed heat transfer liquid circuit, the heat transfer liquid circuit comprising a heat exchanger configured to exchange heat with the first interior airflow to the vehicle passenger compartment.

[0016] According to the proposed method, the third exchanger operates as a refrigerant fluid condenser.

[0017] According to the proposed method, the fourth exchanger operates as a refrigerant evaporator.

[0018] The fourth expansion valve is configured to expand the refrigerant between an outlet of the first exchanger and an inlet of the third exchanger.

[0019] The refrigerant from the first exchanger is expanded by passing through the fourth expansion valve. The refrigerant expanded to an intermediate pressure reaches an inlet of the third exchanger.

[0020] The fifth expansion valve is configured to expand the refrigerant between an outlet of the third exchanger and an inlet of the fourth exchanger.

[0021] The refrigerant from the third exchanger is expanded by passing through the fifth expansion valve. The refrigerant, expanded to a low pressure, reaches an inlet of the fourth exchanger.

[0022] The third heat exchanger allows the vehicle's electric powertrain element to be selectively cooled or heated. The vehicle's electric powertrain element can thus be maintained, or placed, in a preferred temperature range corresponding to the optimal operation of this element.

[0023] According to an exemplary embodiment, the element of the electric powertrain of the vehicle comprises an electrical energy storage battery.

[0024] Alternatively or additionally, the element of the vehicle's electric powertrain comprises an electric vehicle traction motor.

[0025] Alternatively or additionally, the element of the vehicle's electric powertrain comprises an electronic unit for controlling the vehicle's electric traction motor.

[0026] According to an exemplary embodiment, the third heat exchanger is thermally coupled with the element of the electric traction chain by means of a heat transfer fluid circulating in a heat transfer fluid circuit.

[0027] Each regulator is for example an electronic regulator.

[0028] According to an example of implementation of the proposed method, the first regulator is in the closed position.

[0029] According to an example of implementation of the proposed method, the second regulator is in the closed position.

[0030] According to an example of implementation of the proposed method, the third regulator is in the closed position.

[0031] According to an example of implementation of the proposed method, the sixth regulator is in the closed position.

[0032] According to an embodiment of the proposed control method, in which the second branch branch comprises a sixth regulator arranged between the seventh connection point and the fourth connection point: - the first regulator, the second regulator, the third regulator and the sixth regulator are in the closed position.

[0033] According to one embodiment, the control method comprises the step: - receive a temperature setpoint for the second interior air flow at the outlet of the fourth exchanger, - determine a temperature of the second interior air flow at the outlet of the fourth exchanger, - control a flow rate of refrigerant in the refrigerant circuit so that the determined temperature of the second interior air flow leaving the fourth exchanger is equal to the temperature setpoint.

[0034] According to one aspect of the control method, the method comprises the step: - control the compressor rotation speed in order to control the flow of refrigerant in the refrigerant circuit.

[0035] According to one embodiment, the control method comprises the step: - increase the compressor rotation speed when the determined temperature of the second indoor air flow is higher than the set temperature.

[0036] Similarly, the control method may include the step: - reduce the compressor rotation speed when the determined temperature of the second interior air flow is lower than the set temperature.

[0037] According to one embodiment, the control method comprises the steps: - receive a temperature setpoint for the first interior air flow leaving the first exchanger, - determine the temperature of the first interior air flow leaving the first exchanger, - control the pressure of the refrigerant fluid in the third exchanger so that the determined temperature of the first interior air flow leaving the first exchanger is equal to the temperature setpoint.

[0038] According to one aspect of the proposed method, the method comprises the step: - control the expansion of the refrigerant fluid in the fourth expansion valve in order to control the pressure of the refrigerant fluid in the third exchanger.

[0039] The proposed control method may include the step: - reduce a passage section of the fourth expansion valve when the determined temperature of the first interior air flow leaving the first exchanger is lower than the temperature setpoint.

[0040] Similarly, the proposed control method may include the step: - increase a passage section of the fourth expansion valve when the determined temperature of the first interior air flow leaving the first exchanger is higher than the temperature setpoint.

[0041] According to one embodiment, the control method comprises the step: - determine the maximum permissible pressure of the refrigerant fluid at the compressor outlet, - determine the pressure of the refrigerant fluid at the compressor outlet, - check the expansion of the refrigerant fluid in the fifth expansion valve so that the determined pressure of the refrigerant fluid at the compressor outlet is lower than the maximum admissible pressure.

[0042] The proposed control method may include the step: - increase a passage section of the fifth expander when the pressure of the refrigerant fluid at the compressor outlet is higher than a target value.

[0043] Similarly, the proposed control method may include the step: - reduce a passage section of the fifth expansion valve when the pressure of the refrigerant fluid at the compressor outlet is lower than a target value.

[0044] According to one embodiment, the thermal conditioning system comprises a mobile device configured to vary a passage section of the outside air flow towards the second exchanger, the passage section being able to vary between a minimum value and a maximum value.

[0045] The control process may include the step: - control the mobile device for varying the passage section of the outside air flow so that the passage section is equal to the minimum value.

[0046] Since the second exchanger does not participate in heat exchange in the proposed operating mode, it is possible to block the air circulation at the second exchanger. This exchanger is generally located at the front of the vehicle. The air circulation at the front of the vehicle can thus be optimized, which reduces the resistance to movement and therefore the energy consumption of the vehicle.

[0047] The mobile device for varying the passage section of the outside air flow is arranged upstream of the second heat exchanger according to the direction of the outside air flow.

[0048] The mobile device comprises, for example, a set of shutters movable by a control mechanism coupled to an electric motor.

[0049] The mobile device for varying the passage section of the external air flow is movable between a position in which the passage section of the air flow outside is maximum and a second position in which the passage section of the outside air flow is minimum.

[0050] The minimum flow section can be zero. In other words, the movable flap can be in the closed position, and the second exchanger does not receive air. The vehicle's aerodynamic losses are thus reduced.

[0051] A thermal conditioning system for a motor vehicle is also proposed, comprising a refrigerant fluid circuit comprising: - a main loop comprising successively, depending on the direction of circulation of the refrigerant fluid: -- a compressor, -- a first heat exchanger thermally coupled with a first flow of air inside a passenger compartment of the vehicle, -- a first regulator, -- a second regulator, -- a second heat exchanger configured to exchange heat with an air flow outside the vehicle passenger compartment, -- a refrigerant fluid accumulation device, - a first bypass branch connecting a first connection point arranged on the main loop downstream of a compressor outlet and upstream of the first exchanger to a second connection point arranged on the main loop downstream of the second heat exchanger and upstream of the accumulation device, the first bypass branch comprising a third expansion valve, - a second branch connecting a third connection point arranged on the main loop between the first exchanger and the second expander, for example between the first exchanger and the first expander, to a fourth connection point arranged on the main loop downstream of the second exchanger and upstream of the accumulation device, the second branch successively comprising a fourth expander and a third heat exchanger thermally coupled with an element of an electric traction chain of a motor vehicle. - a third branch connecting a fifth connection point arranged on the main loop between the second expansion valve and the first expansion valve to a sixth connection point arranged on the main loop between the second connection point and the fourth connection point, the third branch successively comprising a fifth expansion valve and a fourth heat exchanger configured to exchange heat with a second interior air flow, - a fourth branch connection connecting a seventh connection point located on the second branch connection downstream of the third exchanger and upstream of the fourth connection point to an eighth connection point located on the main loop between the fifth connection point and the second regulator, - an electronic control unit configured to implement the method as described above.

[0052] The refrigerant circuit is configured to circulate a refrigerant.

[0053] The second branch branch includes a sixth regulator arranged between the seventh connection point and the fourth connection point.

[0054] According to one embodiment, the thermal conditioning system comprises: - A fifth branch connection connecting a ninth connection point located on the main loop downstream of the first connection point and upstream of the first exchanger to a tenth connection point located on the second branch connection downstream of the fourth regulator and upstream of the seventh connection point, the fifth branch connection comprising a seventh regulator.

[0055] The fifth bypass branch allows the high-pressure, high-temperature refrigerant at the compressor outlet to return to the compressor inlet without passing through the first or second exchanger. The fifth bypass branch allows the high-pressure refrigerant to be returned to the accumulator inlet, the third exchanger being the only one heat exchanger traveled. The flow circulating in the fifth bypass branch increases the total flow of refrigerant supplied by the compressor and thus increases the heating thermal power supplied by the refrigerant.

[0056] The main loop includes an internal exchanger configured to allow heat exchange between the refrigerant circulating between the first expansion valve and the second expansion valve and the refrigerant downstream of the accumulation device and upstream of a compressor inlet.

[0057] The refrigerant circuit comprises a first one-way valve arranged on the main loop between the first exchanger and the third connection point.

[0058] The first one-way valve is configured to allow circulation of refrigerant from the first exchanger to the third connection point. The first one-way valve is also configured to prohibit circulation of refrigerant from the third connection point to the first exchanger.

[0059] The refrigerant circuit includes a second one-way valve arranged on the fourth bypass branch.

[0060] The second one-way valve being configured to allow circulation of refrigerant fluid from the seventh connection point to the eighth connection point and configured to prohibit circulation of refrigerant fluid from the eighth connection point to the seventh connection point. The refrigerant circuit includes a third one-way valve located on the main loop between the fourth exchanger and the sixth connection point.

[0061] The third one-way valve is configured to allow refrigerant fluid to flow from the fourth exchanger to the sixth connection point. The third one-way valve is also configured to prohibit the circulation of refrigerant fluid from the sixth connection point to the fourth exchanger.

[0062] The first one-way valve is, for example, a check valve. Similarly, the second one-way valve and the third one-way valve can be a check valve.

[0063] The main loop includes a first shutoff valve disposed between the first connection point and the first heat exchanger.

[0064] The main loop includes a second shut-off valve located between the second connection point and the sixth connection point.

[0065] The first shut-off valve is an electrically operated valve. Similarly, the second shut-off valve is an electrically operated valve. Brief description of the drawings

[0066] Other features, details and advantages will become apparent upon reading the detailed description below, and upon analyzing the attached drawings, in which:

[0067] [Fig. 1] is a schematic view of a thermal conditioning system according to a first embodiment of the invention,

[0068] [Fig. 2] is a schematic view of a thermal conditioning system according to a second embodiment of the invention,

[0069] [Fig. 3] is a schematic view illustrating the operation of the thermal conditioning system of Figure 2, when the proposed method is implemented,

[0070] [Fig. 4] is a block diagram of the proposed process. Description of the embodiments

[0071] To facilitate reading of the figures, the different elements are not necessarily represented to scale. In these figures, identical elements bear the same references. Some elements or parameters may be indexed, i.e. designated for example by first element or second element, or first parameter and second parameter, etc. This indexing aims to differentiate between similar, but not identical, elements or parameters. This indexing does not imply a priority of one element or parameter over another and the names can be interchanged.

[0072] In the following description, the expression "a first element upstream of a second element" means that the first element is placed before the second element relative to the direction of circulation, or path, of a fluid. Similarly, the term "a first element downstream of a second element" means that the first element is placed after the second element relative to the direction of circulation, or path, of the fluid in question. In the case of the refrigerant circuit, the term "a first element is upstream of a second element" means that the refrigerant passes successively through the first element, then the second element, without passing through the compression device. In other words, the refrigerant leaves the compression device, possibly passes through one or more elements, then passes through the first element, then the second element, then returns to the compression device, possibly after passing through other elements.

[0073] The expression "a second element is placed between a first element and a third element" means that the shortest path from the first element to the third element or from the third element to the first element passes through the second element.

[0074] When it is specified that a subsystem includes a given element, this does not exclude the presence of other elements in this subsystem.

[0075] The thermal conditioning system 100 which will be described comprises an electronic control unit 60 receiving information from various sensors measuring in particular the characteristics of the refrigerant fluid at various points in the circuit. The electronic control unit 60 also receives instructions issued by the occupants of the vehicle, for example the desired temperature inside the passenger compartment. The electronic control unit 60 can also receive instructions from other electronic subsystems, such as a system for managing electrical energy storage batteries. The electronic control unit 60 implements control laws allowing the various actuators to be controlled, in order to ensure control of the thermal conditioning system 100 so as to ensure the instructions received.

[0076] A compression device 7, also called a compressor, makes it possible to circulate a refrigerant fluid in a refrigerant circulation circuit 10. The compression device 7 may be an electric compressor, that is to say a compressor whose moving parts are driven by an electric motor. The compression device 7 comprises a suction side for the refrigerant fluid at low pressure, also called the inlet 7a of the compression device, and a discharge side for the refrigerant fluid at high pressure, also called the outlet 7b of the compression device 7. The internal moving parts of the compressor 7 cause the refrigerant fluid to pass from a low pressure on the inlet side 7a to a high pressure on the outlet side 7b. After expansion in one or more expansion members and circulation in at least part of the circuit, the refrigerant fluid returns to the inlet 7a of the compressor 7 and begins a new thermodynamic cycle.

[0077] The refrigerant circuit 10 forms a closed circuit in which the refrigerant can circulate. The refrigerant circuit 10 is sealed when it is in a nominal operating state, i.e. without defects or leaks. Each connection point of the circuit 10 allows the refrigerant to pass into one or other of the circuit portions joining at this connection point. The distribution of the refrigerant between the circuit portions joining at a connection point is achieved by adjusting the opening or closing of the stop valves, non-return valves or expansion devices included on each of these portions. In other words, each connection point is a means of redirecting the refrigerant arriving at this connection point. Various stop valves and non-return valves thus make it possible to selectively direct the refrigerant into the different branches of the refrigerant circuit, in order to ensure different operating modes, as will be described later.

[0078] The refrigerant used by the refrigerant circuit 10 is here a natural fluid, such as R744. It is also possible to use a chemical refrigerant, such as R1234yf, or R134a.

[0079] Each refrigerant fluid expansion device, also called an expansion valve, can be an electronic expansion valve. In an electronic expansion valve, the flow area for passing the refrigerant fluid can be continuously adjusted between a closed position and a fully open position. To achieve this, an electronic expansion valve control module drives an electric motor that moves a movable shutter controlling the flow area offered to the refrigerant fluid. In the closed position, also called the closed position, the circulation of refrigerant fluid is interrupted, i.e. the flow of refrigerant fluid passing through the electronic expansion valve is zero. In the fully open position, the refrigerant fluid passes through the expansion valve without undergoing expansion.

[0080] Interior air flow Fi is understood to mean an air flow to the passenger compartment of the motor vehicle. This interior air flow Fi can circulate in a heating, ventilation and / or air conditioning installation, frequently referred to by the English term "HVAC", for "Heating, Ventilating and Air Conditioning". This installation has not been shown in the various figures. A first motor-fan unit, not shown, is arranged in the heating, ventilation and / or air conditioning installation in order to increase the flow rate of the interior air flow Fi if necessary.

[0081] Outside air flow Fe is understood to mean an air flow that is not intended for the passenger compartment of the vehicle. In other words, this air flow Fe remains outside the passenger compartment of the vehicle. A second motor-fan unit, also not shown, can be activated in order to increase the flow rate of the outside air flow Fe if necessary. The air flow rate provided by the first as well as by the second motor-fan unit can be adjusted in real time according to the heat exchange requirements, for example by the electronic unit 60 for controlling the thermal conditioning system 100.

[0082] The term "first exchanger" is equivalent to the term "first heat exchanger". Similarly, the term "internal exchanger" is equivalent to the term "internal heat exchanger". The term "accumulation device" is equivalent to the term "refrigerant accumulation device".

[0083] The thermal conditioning system 100 may comprise one or more heat transfer fluid circuits. These heat transfer fluid circuits also form one or more closed and sealed circuits in which a heat transfer fluid can circulate.

[0084] Figure 1 shows a thermal conditioning system 100 for a motor vehicle, comprising a refrigerant fluid circuit 10. The refrigerant circuit 10 comprises a main loop A comprising successively, according to the direction of circulation of the refrigerant: -- a compressor 7, -- a first heat exchanger 1 thermally coupled with a first interior air flow Fi-1 to a passenger compartment of the vehicle, -- a first regulator 31, -- a second regulator 32, -- a second heat exchanger 2 configured to exchange heat with an outside air flow Fe to the passenger compartment of the vehicle, -- a refrigerant fluid accumulation device 8. The refrigerant circuit 10 further comprises a first bypass branch B connecting a first connection point 11 arranged on the main loop A downstream of an outlet 7b of the compressor 7 and upstream of the first exchanger 1 to a second connection point 12 arranged on the main loop A downstream of the second heat exchanger 2 and upstream of the accumulation device 8, the first bypass branch B comprising a third expansion valve 33. The refrigerant circuit 10 further comprises a second bypass branch C connecting a third connection point 13 arranged on the main loop A between the first exchanger 1 and the second expansion valve 32, in particular between the first exchanger 1 and the first expansion valve 31, to a fourth connection point 14 arranged on the main loop A downstream of the second exchanger 2 and upstream of the accumulation device 8, the second bypass branch C successively comprising a fourth expansion valve 34 and a third heat exchanger 3 thermally coupled with an element 25 of an electric traction chain of a motor vehicle. The refrigerant circuit 10 further comprises a third bypass branch D connecting a fifth connection point 15 arranged on the main loop A between the second expansion valve 32 and the first expansion valve 31 to a sixth connection point 16 arranged on the main loop A between the second connection point 12 and the fourth connection point 14, the third bypass branch D successively comprising a fifth expansion valve 35 and a fourth heat exchanger 4 configured to exchange heat with a second interior air flow Fi-2. The refrigerant circuit 10 further comprises a fourth bypass branch E connecting a seventh connection point 17 arranged on the second bypass branch C downstream of the third exchanger 3 and upstream of the fourth connection point 14 to an eighth connection point 18 arranged on the main loop A between the fifth connection point 15 and the second expansion valve 32. The thermal conditioning system 100 comprises an electronic control unit 60 configured to implement the method which will be described in detail below.

[0085] The refrigerant circuit 10 is configured to circulate a refrigerant. The compressor 7 passes the refrigerant fluid from a low pressure state, at the inlet 7a of the compressor 7, to a high pressure state, at the outlet 7b of the compressor 7.

[0086] The accumulation device 8, also called an accumulator, forms a storage volume for liquid refrigerant. The accumulation device 8 makes it possible to compensate for variations depending on the operating conditions in the quantity of refrigerant circulating in the circuit 10. The accumulation device 8 also makes it possible to separate the liquid phase and the gaseous phase of the refrigerant so as to supply the compressor 7 with refrigerant in gaseous form.

[0087] The first indoor airflow Fi-1 can be identical to the second indoor airflow Fi-2. In other words, the air flow forming the first indoor air flow Fi-1 can be equal to the air flow forming the second indoor air flow Fi-2.

[0088] The first indoor airflow Fi-1 may be distinct from the second indoor airflow Fi-2. In particular, the air flow rate forming the first indoor air flow Fi-1 may be lower than the air flow rate forming the second indoor air flow Fi-2. In other words, part of the second indoor air flow Fi-2 can bypass the first exchanger 1.

[0089] The fourth exchanger 4 is arranged in the heating, ventilation and / or air conditioning system of the vehicle.

[0090] The fourth exchanger 4 is arranged upstream of the first exchanger 1 in a flow direction of the second interior air flow Fi-2. A movable flap, not shown, can direct the first interior air flow Fi 1 after it has passed through the first exchanger 1 . In certain positions of this movable flap, a portion of the first interior air flow Fi1 can bypass the first exchanger 1 , while the remainder of the first interior air flow Fi1 passes through the first exchanger 1 and therefore performs a heat exchange with the refrigerant circulating in the first exchanger. The proportion of the first interior air flow Fi-1 bypassing the first exchanger can vary continuously depending on the position of the movable flap. This proportion can be zero, which corresponds to the case where the first indoor air flow Fi-1 and the second indoor air flow Fi-2 are identical.

[0091] The second branch C comprises a sixth regulator 36 arranged between the seventh connection point 17 and the fourth connection point 14.

[0092] The refrigerant circuit 10 includes several one-way valves and shutoff valves, in order to selectively circulate the refrigerant in various parts of the circuit, depending on the desired operating mode for the thermal conditioning system 100.

[0093] The refrigerant circuit 10 comprises a first one-way valve 43 arranged on the main loop A between the first exchanger 1 and the third connection point 13. The first one-way valve 43 is configured to allow circulation of refrigerant fluid from the first exchanger 1 to the third connection point 13. The first one-way valve 43 is also configured to prohibit circulation of refrigerant fluid from the third connection point 13 to the first exchanger 1.

[0094] The refrigerant circuit 10 comprises a second one-way valve 44 arranged on the fourth bypass branch E. The second one-way valve 44 is configured to allow circulation of refrigerant fluid from the seventh connection point 17 to the eighth connection point 18 and configured to prohibit circulation of refrigerant fluid from the eighth connection point 18 to the seventh connection point 17.

[0095] The refrigerant circuit 10 comprises a third one-way valve 45 arranged on the main loop A between the fourth exchanger 4 and the sixth connection point 16. The third one-way valve 45 is configured to allow circulation of refrigerant fluid from the fourth exchanger 4 to the sixth connection point 16. The third one-way valve 45 is also configured to prohibit circulation of refrigerant fluid from the sixth connection point 16 to the fourth exchanger 4.

[0096] The first one-way valve 43 is for example a non-return valve. Similarly, the second one-way valve 44 and the third one-way valve 45 may be a non-return valve. A check valve is a passive device that reacts to the pressure difference between its inlet and outlet. No electrical control is required.

[0097] The main loop A comprises a first shut-off valve 41 arranged between the first connection point 11 and the first heat exchanger 1.

[0098] The first shut-off valve 41 is, for example, a two-way valve. The first shut-off valve 41 is arranged between the first connection point 11 and the ninth connection point 19. Alternatively, the first shut-off valve 41 may be an electronic expansion valve having a closed position, i.e. a position in which the flow rate of refrigerant through the expansion valve is zero.

[0099] The main loop A comprises a second shut-off valve 42 disposed between the second connection point 12 and the sixth connection point 16. The second shut-off valve 42 is a two-way valve. The second shut-off valve 42 is disposed between the second connection point 12 and the sixth connection point 16.

[0100] The first shut-off valve 41 is an electrically operated valve. Similarly, the second shut-off valve 42 is an electrically operated valve.

[0101] The thermal coupling between the first heat exchanger 1 and the first indoor air flow Fi-1 can be ensured in different ways.

[0102] According to the illustrated example, the first heat exchanger 1 is configured to exchange heat with the first interior air flow Fi-1 to the passenger compartment of the vehicle.

[0103] The thermal coupling between the first heat exchanger 1 and the first indoor air flow Fi-1 is said to be direct. Indeed, the first indoor air flow Fi-1 is in contact with the walls of the heat exchanger 1 in which the refrigerant circulates. In this embodiment, the first exchanger 1 is arranged in the heating, ventilation and / or air conditioning system of the vehicle.

[0104] According to an alternative embodiment not shown, the first heat exchanger 1 is configured to exchange heat with a heat transfer fluid circulating in a closed heat transfer fluid circuit. The closed heat transfer fluid circuit comprises a heat exchanger configured to exchange heat with the first interior air flow Fi-1 in the passenger compartment of the vehicle.

[0105] The thermal coupling between the first heat exchanger 1 and the first interior air flow Fi-1 is in this case called indirect, since it is achieved by means of a heat transfer fluid which transfers the heat supplied by the refrigerant fluid to the air flow Fi supplying the passenger compartment of the vehicle. The heat transfer fluid circulating in the circuit is, for example, a mixture of water and glycol. In this variant, the heat exchanger of the heat transfer fluid circuit, also called the heating radiator, is arranged in the heating, ventilation and / or air conditioning system of the vehicle.

[0106] The second exchanger 2 is for example arranged in the front face of the vehicle, in order to directly receive the exterior air flow Fe.

[0107] The third heat exchanger 3 makes it possible to selectively cool or heat the element 25 of the electric powertrain of the vehicle. The element 25 of the vehicle's electric powertrain can thus be maintained, or placed, in a preferred temperature range corresponding to the optimal operation of this element.

[0108] According to an exemplary embodiment, the element 25 of the electric powertrain of the vehicle comprises an electrical energy storage battery. Alternatively or additionally, the element 25 of the electric traction chain of the vehicle comprises an electric traction motor of the vehicle. Alternatively or additionally, the element 25 of the electric traction chain of the vehicle comprises an electronic unit for controlling the electric traction motor of the vehicle.

[0109] According to the illustrated example, the third heat exchanger 3 is thermally coupled with the element 25 of the electric traction chain by means of a heat transfer liquid circulating in a heat transfer liquid circuit 40.

[0110] The heat transfer fluid circulating in the heat transfer fluid circuit 40 can exchange heat on the one hand with the refrigerant fluid circulating in the third heat exchanger 3 and on the other hand with the element 25 of the electric drive chain of the vehicle. The heat transfer fluid thus allows a transfer thermal between the refrigerant fluid and element 25 of the electric traction chain. For example, the heat transfer fluid circulates between the battery cells, or inside the wall of the electric motor housing. The heat transfer fluid circulating in the circuit 40 is, for example, a mixture of water and glycol.

[0111] Each regulator 31, ..., 36 is for example an electronic regulator.

[0112] Figure 2 illustrates a second embodiment. This embodiment differs from the first embodiment by the presence of additional elements.

[0113] The main loop A comprises an internal exchanger 6 configured to allow heat exchange between the refrigerant circulating between the first expansion valve 31 and the second expansion valve 32 and the refrigerant downstream of the accumulation device 8 and upstream of an inlet 7a of the compressor 7.

[0114] The internal exchanger 6 comprises a first heat exchange section 6a arranged on the main loop A between the first expander 31 and the second expander 32, as well as a second heat exchange section 6b arranged on the main loop A downstream of the accumulator 8 and upstream of the inlet 7a of the compressor 7. The internal exchanger 6, also called internal heat exchanger, is configured to allow heat exchange between the refrigerant in the first heat exchange section 6a and the refrigerant in the second heat exchange section 6b.

[0115] In this second embodiment, the thermal conditioning system 100 further comprises a fifth bypass branch F connecting a ninth connection point 19 arranged on the main loop A downstream of the first connection point 11 and upstream of the first exchanger 1 to a tenth connection point 20 arranged on the second bypass branch C downstream of the fourth expansion valve 34 and upstream of the seventh connection point 17. The fifth bypass branch F comprises a seventh expansion valve 37.

[0116] The fifth bypass branch F allows the high-pressure, high-temperature refrigerant fluid at the outlet of the compressor 7 to return to the inlet of the compressor 7 without passing through the first exchanger 1 or the second exchanger 2. The fifth bypass branch F forms a refrigerant fluid passage allowing the high-pressure refrigerant fluid to be returned to the inlet of the accumulator 8, the third exchanger 3 being the only heat exchanger passed through between the outlet 7b of the compressor 7 and the inlet 7a of the compressor 7. The flow circulating in the fifth bypass branch F makes it possible to increase the total flow rate of refrigerant fluid supplied by the compressor 7 and thus increase the heating thermal power supplied by the refrigerant fluid.

[0117] In this embodiment, the thermal conditioning system also comprises a mobile device 50 configured to vary a passage section of the outside air flow Fe towards the second exchanger 2, the passage section being able to vary between a minimum value and a maximum value.

[0118] The mobile device 50 is an active grille shutter. The mobile device 50 for varying the passage section of the outside air flow Fe is arranged upstream of the second heat exchanger 2 in the direction of the outside air flow Fe. The mobile device 50 comprises, for example, a set of shutters movable by a control mechanism coupled to an electric motor.

[0119] The mobile device 50 for varying the passage section of the external air flow Fe is movable between a position R1 in which the passage section of the external air flow Fe is maximum and a second position P2 in which the passage section of the external air flow Fe is minimum.

[0120] The minimum flow section can be zero. In other words, the movable flap can be in the closed position, and the second exchanger 2 does not receive air. The vehicle's aerodynamic losses can thus be reduced.

[0121] For example, a set of substantially planar flaps may for example pivot so that their orientation varies between a position in which the plane of the flaps is parallel to the airflow and a position in which the plane of the flaps is perpendicular to the airflow.

[0122] The fifth branch branch F, the internal exchanger 6, and the mobile device 50 for varying the passage section of the external air flow Fe are elements independent of each other. Thus, according to variants not shown, only one of these three elements may be present. Similarly, two of these elements may be present. In the example shown, the three elements are present jointly.

[0123] The thermal conditioning system 100 can operate in several operating modes. The proposed method, when implemented, corresponds to a particular operating mode of the thermal conditioning system 100.

[0124] A method for controlling a thermal conditioning system for a motor vehicle is thus proposed. The thermal conditioning system 100 comprises a refrigerant circuit 10, the refrigerant circuit 10 comprising: - a main loop A comprising successively according to the direction of circulation of the refrigerant fluid: -- a compressor 7, -- a first heat exchanger 1 thermally coupled with a first interior air flow Fi-1 to a passenger compartment of the vehicle, -- a first regulator 31, -- a second regulator 32, -- a second heat exchanger 2 configured to exchange heat with an outside air flow Fe to the passenger compartment of the vehicle, -- a refrigerant fluid accumulation device 8, - a first bypass branch B connecting a first connection point 11 arranged on the main loop A downstream of an outlet 7b of the compressor 7 and upstream of the first exchanger 1 to a second connection point 12 arranged on the main loop A downstream of the second heat exchanger 2 and upstream of the accumulation device 8, the first bypass branch B comprising a third expansion valve 33, - a second branch of derivation C connecting a third connection point 13 arranged on the main loop A between the first exchanger 1 and the second expander 32, in particular between the first exchanger 1 and the first expander 31, at a fourth connection point 14 arranged on the main loop A downstream of the second exchanger 2 and upstream of the accumulation device 8, the second branch branch C successively comprising a fourth expander 34 and a third heat exchanger 3 thermally coupled with an element 25 of an electric traction chain of a motor vehicle, - a third branch branch D connecting a fifth connection point 15 arranged on the main loop A between the second expansion valve 32 and the first expansion valve 31 to a sixth connection point 16 arranged on the main loop A between the second connection point 12 and the fourth connection point 14, the third branch branch D successively comprising a fifth expansion valve 35 and a fourth heat exchanger 4 configured to exchange heat with a second interior air flow Fi-2, - a fourth branch E connecting a seventh connection point 17 arranged on the second branch C downstream of the third exchanger 3 and upstream of the fourth connection point 14 to an eighth connection point 18 arranged on the main loop A between the fifth connection point 15 and the second regulator 32, the method comprising the successive steps: (i) provide a flow of high-pressure refrigerant fluid at the outlet of the compressor 7, (ii) circulating high pressure refrigerant fluid in the first heat exchanger 1, (iii) expanding the high pressure refrigerant from the first heat exchanger 1 to an intermediate pressure lower than the high pressure, (iv) circulating the refrigerant at intermediate pressure in the third exchanger 3, (v) expanding the refrigerant fluid from the third exchanger 3 to a low pressure lower than the intermediate pressure, (vi) circulating the refrigerant at low pressure in the fourth exchanger 4.

[0125] The refrigerant heats the first indoor air flow Fi-1 at the first exchanger 1 and cools the second indoor air flow Fi-2 at the fourth exchanger 4. The indoor air flow Fi is thus dehumidified. When the total available heating power is greater than the heating power requirement at the first exchanger 1, the excess heating power must be dissipated at another heat exchanger. According to conventional methods, this excess power is dissipated in the outside air flow Fe at the second exchanger 2. This excess thermal power is thus lost, since it is dissipated in the outside air and cannot be reused. In the proposed method, the heat exchanger in which the excess heating power is dissipated is the third exchanger 3, which is thermally coupled to an element 25 of the vehicle's powertrain. The second exchanger 2 does not participate in the heat exchanges. The excess heat can thus be used to thermally condition this element 25 of the vehicle's powertrain, which can be, for example, the electrical energy storage battery. The excess heat produced by the thermal conditioning system can be dissipated in the third exchanger 3 and can be used to heat, for example, the vehicle's battery, when the latter is cold, typically to a temperature below 15°C.

[0126] According to the proposed method, the first exchanger 1 operates as a refrigerant fluid cooler. The third exchanger 3 operates as a refrigerant fluid condenser. The fourth exchanger 4 operates as a refrigerant fluid evaporator.

[0127] The fourth expansion valve 34 is configured to expand the refrigerant fluid between an outlet 1b of the first exchanger 1 and an inlet 3a of the third exchanger 3. The refrigerant fluid coming from the first exchanger 1 is expanded by passing through the fourth expansion valve 34. The refrigerant fluid expanded to an intermediate pressure reaches an inlet 3a of the third exchanger 3.

[0128] The fifth expander 35 is configured to expand the refrigerant fluid between an outlet 3b of the third exchanger 3 and an inlet 4a of the fourth exchanger 4. The refrigerant fluid coming from the third exchanger 3 is expanded by passing through the fifth expansion valve 35. The refrigerant fluid expanded to a low pressure reaches an inlet of the fourth exchanger 4.

[0129] According to the example illustrated, the first regulator 31 is in the closed position. Thus, the entire flow of refrigerant fluid passing through the first exchanger 1 also passes through the third exchanger 3.

[0130] According to the illustrated example, the second regulator 32 is in the closed position. Similarly, the third regulator 33 is in the closed position.

[0131] Thus, the second exchanger 2 does not participate in heat exchanges.

[0132] According to the illustrated example, the sixth regulator 36 is in the closed position. Thus, the entire flow of refrigerant fluid passing through the third exchanger 3 also passes through the fourth exchanger 4.

[0133] Thus, the first regulator 31, the second regulator 32, the third regulator 33 and the sixth regulator 36 are in the closed position. The sixth regulator 36 is arranged on the second branch branch C between the seventh connection point 17 and the fourth connection point 14.

[0134] The value of the so-called “high pressure” pressure, at the outlet of compressor 7, is for example between 80 bars and 120 bars. The value of the so-called "intermediate" pressure, after expansion by the fourth regulator 34, is lower than the value of the high pressure. The intermediate pressure is, for example, between 40 bars and 70 bars. The value of the so-called “low pressure”, after expansion in the fifth regulator 35, is lower than the value of the intermediate pressure. Low pressure is for example between 35 bars and 40 bars.

[0135] Figure 3 illustrates the circulation of the refrigerant fluid in the circuit 10 when the proposed method is implemented. The portions of the circuit 10 in which a flow of refrigerant fluid circulates are in continuous thick line, while the portions in which the refrigerant does not circulate are in thin dotted lines.

[0136] A flow rate Q of high pressure refrigerant is supplied by the compressor 7. The high-pressure refrigerant reaches the first connection point 1 1 . The first stop valve 41 is in the open position, and the third expansion valve 33 is in the closed position. All the refrigerant flow therefore circulates in the main loop A, passes through the first stop valve 41 , and passes through the first exchanger 1 , giving up heat to the first interior air flow Fi- 1 . The first expansion valve 31 is in the closed position. At the third connection point 13, the refrigerant flows through the second branch C and then reaches the fourth expansion valve 34. The refrigerant undergoes partial expansion, down to an intermediate pressure state, then flows through the third exchanger 3, giving off heat to the heat transfer fluid of the circuit 40. The seventh regulator 37 is in the closed position, and the fifth bypass branch F is not traversed by refrigerant fluid. The sixth expansion valve 36 is in the closed position, and the fifth expansion valve 35 is in the partially open position. At the seventh connection point 17, the intermediate-pressure refrigerant from the third exchanger 3 flows through the fourth bypass branch E and joins the main loop A at the eighth connection point 18. The second expansion valve 32 is in the closed position. The refrigerant thus flows through the first heat exchange section 6a of the internal exchanger 6, and at the fifth connection point flows through the third bypass branch D. The refrigerant undergoes expansion in the fifth expansion valve 35 and passes to low pressure. The refrigerant evaporates in the fourth exchanger 4 by absorbing heat from the second indoor air flow Fi-2. The second indoor air flow Fi-2 is thus cooled. The second shutoff valve 42 is in the closed position.The low-pressure refrigerant fluid from the fourth exchanger 4 reaches the fourth connection point 14, then circulates in the accumulation device. 8, in the second heat exchange section 6b of the internal exchanger 6, and returns to the inlet 7a of the compressor 7, thus completing the thermodynamic cycle.

[0137] The proposed control method includes the step: - receive a temperature setpoint Tc_4 from the second indoor air flow Fi-2 at the outlet of the fourth exchanger 4, - determine a temperature T4 of the second interior air flow Fi-2 at the outlet of the fourth exchanger 4, - controlling a flow rate of refrigerant fluid in the refrigerant fluid circuit 10 so that the determined temperature T4 of the second interior air flow Fi-2 at the outlet of the fourth exchanger 4 is equal to the temperature setpoint Tc_4.

[0138] The temperature of an air flow leaving a heat exchanger is understood to be the temperature of this air flow after having carried out a heat exchange with the refrigerant circulating in this heat exchanger.

[0139] The temperature T4 of the second indoor air flow Fi-2 at the outlet of the fourth exchanger 4 can for example be determined by a measurement sensor arranged in the second indoor air flow Fi-2, close to the fourth exchanger 4 and downstream of the latter in a flow direction of the second indoor air flow Fi-2. According to alternative embodiments, the temperature T4 of the second indoor air flow Fi-2 at the outlet of the fourth exchanger 4 can be determined from a temperature measurement carried out at another point of passage of the second indoor air flow Fi-2 and from a model of temperature evolution between the point where the measurement is carried out and the outlet of the fourth exchanger 4 for the second indoor air flow Fi-2.

[0140] According to one aspect of the control method, the method comprises the step: - control a rotation speed of the compressor 7 in order to control the flow of refrigerant fluid in the refrigerant circuit 10.

[0141] Increasing the rotation speed of the compressor 7 makes it possible to increase the flow rate of refrigerant circulating in the compressor 7 and therefore in the circuit 10. Conversely, reducing the rotation speed of the compressor 7 makes it possible to reduce the flow rate of refrigerant circulating in the circuit 10.

[0142] The control process includes the step: - increase the rotation speed of the compressor 7 when the determined temperature T4 of the second interior air flow Fi-2 is higher than the temperature of setpoint T_c. By increasing the rotation speed of the compressor 7, the flow rate of refrigerant increases, as does the thermal power absorbed at the level of the fourth exchanger 4. The temperature of the second interior air flow Fi-2, after heat exchange with the fourth exchanger 4, tends to approach its set value.

[0143] Similarly, the control process includes the step: - reduce the rotation speed of the compressor 7 when the determined temperature T4 of the second interior air flow Fi-2 is lower than the set temperature Tc_4. By reducing the rotation speed of the compressor 7, the refrigerant flow rate decreases, as does the thermal power absorbed at the fourth exchanger 4. The temperature of the second interior air flow Fi-2, after heat exchange with the fourth exchanger 4, tends to approach its set value.

[0144] According to the illustrated example, the control process includes the steps: - receive a temperature setpoint Tc_1 from the first indoor air flow Fi-1 at the outlet of the first exchanger 1, - determine a temperature T1 of the first interior air flow Fi-1 at the outlet of the first exchanger 1, - control a pressure of the refrigerant fluid in the third exchanger 3 so that the determined temperature T1 of the first interior air flow Fi-1 at the outlet of the first exchanger 1 is equal to the temperature setpoint Tc_1.

[0145] The pressure of the refrigerant fluid in the third exchanger 3 is controlled by acting on the opening of the fourth expansion valve 34.

[0146] The process thus includes the step: - controlling an expansion of the refrigerant fluid in the fourth expansion valve 34 in order to control the pressure of the refrigerant fluid in the third exchanger 3.

[0147] More specifically, the proposed control method may include the step: - reduce a passage section of the fourth regulator 34 when the determined temperature T1 of the first indoor air flow Fi-1 at the outlet of the first exchanger 1 is lower than the temperature setpoint Tc_1.

[0148] Similarly, the proposed control method may include the step: - increase a passage section of the fourth expansion valve 34 when the determined temperature T1 of the first interior air flow Fi-1 at the outlet of the first exchanger 1 is higher than the temperature setpoint Tc_1.

[0149] Reducing the passage section of the fourth regulator 34 makes it possible to increase the expansion rate through the fourth regulator 34, and therefore to reduce the pressure at the outlet 34b of the fourth regulator 34. Conversely, increasing the passage section of the fourth regulator 34 makes it possible to reduce the expansion rate through the fourth regulator 34, and therefore to increase the pressure at the outlet 34b of the fourth regulator 34.

[0150] The control process includes the step: - determine a maximum admissible pressure Pmax of the refrigerant fluid at the outlet of the compressor 7, - determine a pressure P_c of the refrigerant fluid at the outlet of compressor 7, - controlling an expansion of the refrigerant fluid in the fifth expansion valve 35 so that the determined pressure P_c of the refrigerant fluid at the outlet of the compressor 7 is lower than the maximum admissible pressure Pmax.

[0151] The illustrated control process includes the step: - increase a passage section of the fifth expander 35 when the pressure P_c of the refrigerant fluid at the outlet of the compressor 7 is greater than a target value.

[0152] Similarly, the illustrated control method comprises the step: - reduce a passage section of the fifth expander 35 when the pressure P_c of the refrigerant fluid at the outlet of the compressor 7 is lower than a target value.

[0153] When the thermal conditioning system 100 comprises a mobile device 50 for varying the passage section of the outside air flow Fe, a particular control of this mobile device can be carried out.

[0154] Thus, the control process may include the step: - control the mobile device 50 for varying the passage section of the outside air flow Fe so that the passage section is equal to the minimum value.

[0155] Figure 3 schematically illustrates the mobile device 50 placed in position P2 of minimum passage section during the implementation of the proposed method. Since the second exchanger 2 does not participate in the heat exchanges in the proposed operating mode, it is possible to block the circulation of the outside air flow Fe at the level of the second exchanger 2, which is arranged in the example illustrated at the front of the vehicle. The circulation of air at the front of the vehicle can thus be optimized, which makes it possible to reduce the resistance to forward movement and therefore the energy consumption of the vehicle.

Claims

Claims

1. Method for controlling a thermal conditioning system for a motor vehicle, the thermal conditioning system (100) comprising a refrigerant circuit (10), the refrigerant circuit (10) comprising: - a main loop (A) comprising successively, depending on the direction of circulation of the refrigerant fluid: -- a compressor (7), -- a first heat exchanger (1) thermally coupled with a first interior air flow (Fi-1) to a passenger compartment of the vehicle, -- a first regulator (31), -- a second regulator (32), -- a second heat exchanger (2) configured to exchange heat with an external air flow (Fe) to the passenger compartment of the vehicle, -- a refrigerant fluid accumulation device (8), - a first branch branch (B) connecting a first connection point (1 1 ) arranged on the main loop (A) downstream of an outlet (7b) of the compressor (7) and upstream of the first exchanger (1 ) at a second connection point (12) arranged on the main loop (A) downstream of the second heat exchanger (2) and upstream of the accumulation device (8), the first bypass branch (B) comprising a third regulator (33), - a second branch branch (C) connecting a third connection point (13) arranged on the main loop (A) between the first exchanger (1) and the first expansion valve (31) at a fourth connection point (14) arranged on the main loop (A) downstream of the second exchanger (2) and upstream of the accumulation device (8), the second bypass branch (C) successively comprising a fourth expansion valve (34) and a third heat exchanger (3) thermally coupled with an element (25) of an electric traction chain of a motor vehicle, - a third branch branch (D) connecting a fifth connection point (15) arranged on the main loop (A) between the second regulator (32) and the first regulator (31) to a sixth connection point (16) arranged on the main loop (A) between the second connection point (12) and the fourth connection point (14), the third bypass branch (D) successively comprising a fifth expansion valve (35) and a fourth heat exchanger (4) configured to exchange heat with a second interior air flow (Fi-2), - a fourth branch branch (E) connecting a seventh connection point (17) arranged on the second branch branch (C) downstream of the third exchanger (3) and upstream of the fourth connection point (14) to an eighth connection point (18) arranged on the main loop (A) between the fifth connection point (15) and the second regulator (32), the method comprising the successive steps: (i) providing a flow of high-pressure refrigerant fluid at the outlet of the compressor (7), (ii) circulating high pressure refrigerant fluid in the first heat exchanger (1), (iii) expanding the high pressure refrigerant from the first heat exchanger (1) to an intermediate pressure lower than the high pressure, (iv) circulating the refrigerant at intermediate pressure in the third exchanger (3), (v) expanding the refrigerant fluid from the third exchanger (3) to a low pressure lower than the intermediate pressure, (vi) circulating the refrigerant fluid at low pressure in the fourth exchanger (4).

2. Control method according to the preceding claim, in which the second branch branch (C) comprises a sixth regulator (36) arranged between the seventh connection point (17) and the fourth connection point (14), and in which: - the first regulator (31), the second regulator (32), the third regulator (33) and the sixth regulator (36) are in the closed position.

3. A control method according to claim 1 or 2, comprising the steps: - receive a temperature setpoint (Tc_4) from the second interior air flow (Fi-2) at the outlet of the fourth exchanger (4), - determine a temperature (T4) of the second interior air flow (Fi-2) at the outlet of the fourth exchanger (4), - controlling a flow rate of refrigerant fluid in the refrigerant fluid circuit (10) so that the determined temperature (T4) of the second interior air flow (Fi- 2) at the outlet of the fourth exchanger (4) is equal to the temperature setpoint (Tc_4).

4. Control method according to the preceding claim, comprising the step: - control a rotation speed of the compressor (7) in order to control the flow of refrigerant fluid in the refrigerant circuit (10).

5. Control method according to the preceding claim, comprising the steps: - increase the rotation speed of the compressor (7) when the determined temperature (T4) of the second interior air flow (Fi-2) is higher than the set temperature (Tc_4), - reduce the rotation speed of the compressor (7) when the determined temperature (T4) of the second interior air flow (Fi-2) is lower than the set temperature (Tc_4).

6. Control method according to one of the preceding claims, comprising the steps: - receive a temperature setpoint (Tc_1) from the first interior air flow (Fi-1) at the outlet of the first exchanger (1), - determine a temperature (T1) of the first interior air flow (Fi-1) at the outlet of the first exchanger (1), - controlling a pressure of the refrigerant fluid in the third exchanger (3) so that the determined temperature (T1) of the first interior air flow (Fi-1) at the outlet of the first exchanger (1) is equal to the temperature setpoint (Tc_1).

7. Control method according to the preceding claim, comprising the step: - control an expansion of the refrigerant fluid in the fourth expansion valve (34) in order to control the pressure of the refrigerant fluid in the third exchanger (3).

8. Control method according to one of the preceding claims, comprising the step: - determine a maximum admissible pressure (Pmax) of the refrigerant fluid at the outlet of the compressor (7), - determine a pressure (P_c) of the refrigerant fluid at the outlet of the compressor (7), - control an expansion of the refrigerant fluid in the fifth expansion valve (35) so that the determined pressure (P_c) of the refrigerant fluid at the outlet of the compressor (7) is lower than the maximum admissible pressure (Pmax).

9. Control method according to one of the preceding claims, in which the thermal conditioning system (100) comprises a mobile device (50) configured to vary a passage section of the outside air flow (Fe) towards the second exchanger (2), the passage section being able to vary between a minimum value and a maximum value, the control method comprising the step: - control the mobile device (50) for varying the passage section of the external air flow (Fe) so that the passage section is equal to the minimum value.

10. Thermal conditioning system for a motor vehicle, comprising a refrigerant fluid circuit (10) comprising: A main loop (A) comprising successively according to the direction of circulation of the refrigerant fluid: -- a compressor (7), -- a first heat exchanger (1) thermally coupled with a first interior air flow (Fi-1) to a passenger compartment of the vehicle, -- a first expansion valve (31), -- a second regulator (32), -- a second heat exchanger (2) configured to exchange heat with an external air flow (Fe) to the passenger compartment of the vehicle, -- a refrigerant fluid accumulation device (8), A first bypass branch (B) connecting a first connection point (11) arranged on the main loop (A) downstream of an outlet (7b) of the compressor (7) and upstream of the first exchanger (1) to a second connection point (12) arranged on the main loop (A) downstream of the second heat exchanger (2) and upstream of the accumulation device (8), the first bypass branch (B) comprising a third expansion valve (33), - A second branch branch (C) connecting a third connection point (13) arranged on the main loop (A) between the first exchanger (1) and the first pressure reducer (31) to a fourth connection point (14) arranged on the main loop (A) downstream of the second exchanger (2) and upstream of the accumulation device (8), the second branch branch (C) successively comprising a fourth pressure reducer (34) and a third heat exchanger (3) thermally coupled with an element (25) of an electric powertrain of a motor vehicle, - A third branch branch (D) connecting a fifth connection point (15) arranged on the main loop (A) between the second expansion valve (32) and the first expansion valve (31) to a sixth connection point (16) arranged on the main loop (A) between the second connection point (12) and the fourth connection point (14), the third branch branch (D) successively comprising a fifth expansion valve (35) and a fourth heat exchanger (4) configured to exchange heat with a second interior air flow (Fi-2), - A fourth branch branch (E) connecting a seventh connection point (17) arranged on the second branch branch (C) downstream of the third exchanger (3) and upstream of the fourth connection point (14) to an eighth connection point (18) arranged on the main loop (A) between the third connection point (13) and the second regulator (32), - an electronic control unit 60 configured to implement the method according to one of the preceding claims.

11. Thermal conditioning system (100) according to the preceding claim, comprising: - A fifth branch of derivation (F) connecting a ninth point of connection (19) arranged on the main loop (A) downstream of the first connection point (11) and upstream of the first exchanger (1) to a tenth connection point (20) arranged on the second bypass branch (C) downstream of the fourth regulator (34) and upstream of the seventh connection point (17), the fifth bypass branch (F) comprising a seventh regulator (37), - An internal exchanger (6) configured to allow heat exchange between the refrigerant circulating between the first expansion valve (31) and the second expansion valve (32) and the refrigerant downstream of the accumulation device (8) and upstream of an inlet (7a) of the compressor (7).

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