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 main loop (A) of refrigerant (10) successively comprising: -- a compressor (7), -- a first heat exchanger (1) thermally coupled with an interior airflow (Fi) to the passenger compartment, -- a first expansion valve (31), -- a second expansion valve (32), -- a second heat exchanger (2) configured to exchange heat with an exterior airflow (Fe), -- an accumulator (8), -- an internal heat exchanger (6) allowing heat exchange between the refrigerant circulating between the two expansion valves (31, 32), and the refrigerant returning to the compressor (7), the method comprising the steps: - circulating refrigerant at high pressure in the first heat exchanger (1), - expanding the refrigerant to an intermediate pressure and circulating it in the internal heat exchanger (6),- reduce the refrigerant pressure to a low level and circulate it through the second heat exchanger (2). See Figure 3 for an abstract.

Description

Title of the invention: Method for controlling a thermal conditioning system for a motor vehicle Technical field

[0001] 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

[0002] It is known to use carbon dioxide as a refrigerant, which makes it possible to limit to a minimum the global warming potential (GWP coefficient) of the refrigerant used.

[0003] Various thermal conditioning systems adapted to operate with carbon dioxide as the refrigerant have been proposed. These systems can provide many different functions, depending on the heat exchangers in which the refrigerant can circulate, and depending on the expansion rate provided by each of the expansion devices upstream of these exchangers. Possible operating modes include heating the vehicle cabin as well as cooling it, as well as cooling and heating the electrical energy storage batteries.

[0004] In order to further optimize such thermal conditioning systems, it is desirable to optimize the operating modes, as well as their control. Abstract

[0005] For this purpose, a method for controlling a thermal conditioning system for a motor vehicle is proposed. 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 an air flow 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. 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. The proposed process involves the following successive steps: (i) providing a flow of high-pressure refrigerant fluid at the outlet of the compressor, (ii) circulating high-pressure refrigerant fluid in 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 intermediate pressure refrigerant through the internal exchanger, (v) expanding the refrigerant fluid from the internal exchanger to a low pressure lower than the intermediate pressure, (vi) circulating the low-pressure refrigerant in the second exchanger.

[0006] The high-pressure refrigerant transfers heat to the interior air flow at the first exchanger. The low-pressure refrigerant absorbs heat from the exterior air flow at the second exchanger. The vehicle interior can thus be heated by recovering energy from the exterior air flow. After transferring heat to the interior air flow, the high-pressure refrigerant undergoes two successive expansions. The intermediate-pressure refrigerant, after the first of the two expansions, carries out a heat exchange with the low-pressure refrigerant coming from the second exchanger and returning to the compressor. The efficiency of the internal exchanger can be controlled by controlling the value of the intermediate pressure.The inlet temperature of the refrigerant in the compressor can thus be adjusted, which also makes it possible to adjust the discharge temperature at the compressor outlet. The thermomechanical stresses experienced by the compressor parts are thus reduced. In addition, limiting the discharge temperature at the compressor outlet also limits the refrigerant inlet temperature at the inlet of the first exchanger. The refrigerant temperature difference between the inlet and outlet of the first exchanger is thus reduced. The temperature gradient of the interior air flow along the direction of refrigerant flow is thus reduced. Passenger comfort is improved, because the air blown into the passenger compartment can be of a more uniform temperature.

[0007] The features listed in the following paragraphs can be implemented independently of each other or in any technically possible combination:

[0008] The refrigerant circuit is configured to circulate a refrigerant.

[0009] The compressor causes the refrigerant fluid to pass from a low pressure state, at the inlet of the compressor, to a high pressure state, at the outlet of the compressor.

[0010] According to the proposed method, the first exchanger operates as a refrigerant fluid cooler.

[0011] According to an exemplary embodiment, the first heat exchanger is configured to exchange heat with the air flow inside the passenger compartment of the vehicle.

[0012] 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 air flow inside the passenger compartment of the vehicle.

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

[0014] According to other operating modes, the second exchanger can operate selectively as a refrigerant fluid condenser or as a refrigerant fluid evaporator.

[0015] The internal exchanger comprises a first heat exchange section arranged on the main loop between the first expander and the second expander, as well as a second heat exchange section arranged on the main loop downstream of the accumulator and upstream of the compressor inlet.

[0016] The first expander is configured to expand the refrigerant between an outlet of the first exchanger and an inlet of the first heat exchange section of the internal exchanger.

[0017] The second expander is configured to expand the refrigerant fluid between an outlet of the first heat exchange section of the internal exchanger and an inlet of the second exchanger.

[0018] The refrigerant fluid coming from the first heat exchange section of the internal exchanger is expanded to a low pressure by passing through the second expansion valve. The refrigerant fluid expanded to a low pressure then reaches an inlet of the second exchanger.

[0019] According to an example of implementation of the proposed control method, the refrigerant circuit comprises: - a first branch connection connecting a first connection point arranged on the main loop downstream of a compressor outlet and upstream of the first exchanger at 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.

[0020] The refrigerant circuit further comprises: - a second branch connecting a third connection point arranged on the main loop between the first exchanger and the second expansion valve 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 expansion valve and a third heat exchanger thermally coupled with an element of an electric traction chain of a motor vehicle.

[0021] The refrigerant circuit further comprises: - 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 the interior air flow.

[0022] The refrigerant circuit further comprises: - 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.

[0023] The second branch branch may comprise a sixth regulator arranged between the seventh connection point and the fourth connection point.

[0024] According to an example of implementation of the proposed method, the third regulator is in the closed position.

[0025] According to an example of implementation of the proposed method, the fourth regulator is in the closed position.

[0026] According to an example of implementation of the proposed method, the fifth regulator is in the closed position.

[0027] According to an example of implementation of the proposed method, the sixth regulator is in the closed position.

[0028] According to an exemplary implementation of the proposed method, in which the second branch branch comprises a sixth regulator arranged between the seventh connection point and the fourth connection point, - the third regulator, the fourth regulator, the fifth regulator and the sixth regulator are jointly in the closed position.

[0029] The first exchanger and the second exchanger are thus the only exchangers to participate in the heat exchanges.

[0030] Depending on the operating mode, the third heat exchanger makes it possible to selectively cool or heat the element of the vehicle's electric powertrain. The element 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.

[0031] According to an exemplary embodiment, the element of the electric powertrain of the vehicle comprises an electrical energy storage battery.

[0032] Alternatively or additionally, the element of the electric traction chain of the vehicle comprises an electric traction motor of the vehicle.

[0033] As a further variant or in a complementary manner, the element of the electric traction chain of the vehicle comprises an electronic unit for controlling the electric traction motor of the vehicle.

[0034] 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 liquid circulating in a heat transfer liquid circuit.

[0035] The fourth exchanger can operate as a refrigerant fluid evaporator.

[0036] The fifth expander is configured to expand the refrigerant circulating between the main loop and an inlet of the fourth exchanger.

[0037] The fourth exchanger is arranged upstream of the first exchanger in a direction of flow of the interior air flow.

[0038] Each regulator is for example an electronic regulator.

[0039] According to one aspect of the proposed control method, the method comprises the step: - receiving a temperature setpoint for the interior air flow at the outlet of the first exchanger, - determine the temperature of the interior air flow at the outlet of the first exchanger, - control a flow of refrigerant fluid in the refrigerant circuit so that the determined temperature of the interior air flow at the outlet of the first exchanger is equal to the temperature setpoint.

[0040] 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.

[0041] According to one embodiment, the control method comprises the sub-step: - increase the compressor rotation speed when the determined temperature of the interior air flow at the outlet of the first exchanger is lower than the set temperature.

[0042] Similarly, the control method may comprise the sub-step: - reduce the compressor rotation speed when the determined temperature of the interior air flow leaving the first exchanger is higher than the set temperature.

[0043] According to another aspect of the proposed control method, the 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, - control the expansion of the refrigerant fluid in the second expansion valve so that the determined pressure of the refrigerant fluid at the compressor outlet is lower than the maximum admissible pressure.

[0044] The proposed control method may comprise the sub-step: - reduce a passage section of the refrigerant fluid through the second expansion valve if the determined pressure of the refrigerant fluid at the compressor outlet is lower than a target value.

[0045] The proposed control method may comprise the sub-step: - increase a passage section of the refrigerant fluid through the second expansion valve if the determined pressure of the refrigerant fluid at the compressor outlet is higher than a target value.

[0046] According to yet another aspect of the proposed control method, the method may comprise the steps: - determine a maximum admissible temperature of the refrigerant fluid at the compressor outlet, - determine the temperature of the refrigerant fluid at the compressor outlet, - control the expansion of the refrigerant fluid in the first expansion valve so that the determined temperature is lower than the maximum temperature.

[0047] The proposed control method may comprise the step: - reduce a passage section of the refrigerant fluid through the first expansion valve if the determined temperature of the refrigerant fluid at the compressor outlet is higher than a target value.

[0048] Similarly, the proposed control method may include the step: - increase a passage section of the refrigerant fluid through the first expansion valve if the determined temperature of the refrigerant fluid at the compressor outlet is lower than a target value.

[0049] 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 an air flow 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, the main loop comprising an internal exchanger configured to allow heat exchange between the refrigerant fluid circulating between the first expansion valve and the second expansion valve and the refrigerant fluid downstream of the accumulation device and upstream of a compressor inlet, - an electronic control unit configured to implement the method as described above.

[0050] According to one embodiment, the refrigerant circuit further comprises: - a first branch branch connecting a first connection point arranged on the main loop downstream of an outlet of the compressor 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 branch branch comprising a third expansion valve, - a second branch branch connecting a third connection point arranged on the main loop between the first exchanger and the second expansion valve to a fourth connection point arranged on the main loop downstream of the second exchanger and upstream of the accumulation device, the second branch branch successively comprising a fourth expansion valve and a third heat exchanger thermally coupled with an element of an electric powertrain 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 the interior air flow, - a fourth branch E connecting a seventh connection point located on the second branch 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.

[0051] The second branch branch comprises a sixth regulator arranged between the seventh connection point and the fourth connection point.

[0052] According to one embodiment, the thermal conditioning system comprises: - A fifth bypass branch connecting a ninth connection point arranged on the main loop downstream of the first connection point and upstream of the first exchanger to a tenth connection point arranged on the second bypass branch downstream of the fourth expansion valve and upstream of the seventh connection point, the fourth bypass branch comprising a seventh expansion valve.

[0053] 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 exchanger or the second exchanger. The fifth bypass branch allows the high-pressure refrigerant to be returned to the accumulator inlet, the third exchanger being the only heat exchanger passed through. 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.

[0054] The refrigerant circuit comprises a first one-way valve arranged on the main loop between the first exchanger and the third connection point.

[0055] The first one-way valve is configured to allow circulation of refrigerant fluid from the first exchanger to the third connection point. The first one-way valve is also configured to prohibit circulation of refrigerant fluid from the third connection point to the first exchanger.

[0056] The refrigerant circuit comprises a second one-way valve arranged on the fourth bypass branch.

[0057] 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.

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

[0059] The first one-way valve is for example a non-return valve. Similarly, the second one-way valve and the third one-way valve may be a non-return valve.

[0060] The main loop comprises a first shutoff valve disposed between the first connection point and the first heat exchanger.

[0061] The main loop comprises a second shutoff valve disposed between the second connection point and the sixth connection point.

[0062] 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

[0063] Other characteristics, details and advantages will appear on reading the detailed description below, and on analyzing the attached drawings, in which:

[0064] [Fig-1] is a schematic view of a thermal conditioning system according to a first embodiment of the invention,

[0065] [Fig.2] is a schematic view of a thermal conditioning system according to a second embodiment of the invention,

[0066] [Fig.3] is a schematic view illustrating the operation of the air conditioning system thermal operation of [Fig.2], when the proposed method is implemented,

[0067] [Fig.4] is a block diagram of the proposed method. Description of the embodiments

[0068] In order to facilitate the reading of the figures, the different elements are not necessarily represented to scale. In these figures, identical elements bear the same references. Certain elements or parameters may be indexed, that is to say designated for example by first element or second element, or first parameter and second parameter, etc. This indexing is intended to differentiate similar, but not identical, elements or parameters. This indexing does not imply a priority of one element or parameter over another and the names may be interchanged.

[0069] 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 fluid successively passes through the first element, then the second element, without passing through the compression device. In other words, the refrigerant fluid 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.

[0070] The expression "a second element is placed between a first element and a third element" means that the shortest path to go from the first element to the third element or from the third element to the first element passes through the second element.

[0071] When it is specified that a subsystem comprises a given element, this does not exclude the presence of other elements in this subsystem.

[0072] The thermal conditioning system 100 which will be described comprises an electronic control unit 61 receiving information from various sensors measuring in particular the characteristics of the refrigerant fluid at various points in the circuit. The electronic control unit 61 also receives instructions issued by the occupants of the vehicle, such as for example the desired temperature inside the passenger compartment. The electronic control unit 61 can also receive instructions from other electronic subsystems, such as for example the electrical energy storage battery management system. The electronic control unit 61 implements control laws allowing the control of the various actuators, in order to ensure the control of the thermal conditioning system 100 so as to ensure the instructions received. The control unit 61 can execute software encoding the proposed method.

[0073] 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.

[0074] 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, that is to say without fault or leak. Each connection point of circuit 10 allows the refrigerant fluid to pass in one or other of the circuit portions joining at this connection point. The distribution of the refrigerant fluid between the circuit portions joining at a connection point is achieved by opening or closing 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 fluid arriving at this connection point. Various stop valves and non-return valves thus make it possible to selectively direct the refrigerant fluid into the different branches of the refrigerant circuit, in order to ensure different operating modes, as will be described later.

[0075] The refrigerant fluid used by the refrigerant circuit 10 is here a natural fluid, such as R744. It is also possible to use a chemical refrigerant fluid, such as R1234yf, or R 134a.

[0076] Each device for expanding the refrigerant fluid, also called an expansion valve, may be an electronic expansion valve. In an electronic expansion valve, the passage section allowing the refrigerant fluid to pass can be continuously adjusted between a closed position and a maximum open position. For this, an electronic module for controlling the expansion valve drives an electric motor which moves a movable shutter controlling the passage section offered to the refrigerant fluid. In the closed position, also called the closed position, the circulation of refrigerant fluid is interrupted, that is to say that the flow rate of refrigerant fluid passing through the electronic expansion valve is zero. In the maximum open position, the refrigerant fluid passes through the expansion valve without undergoing expansion.

[0077] 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.

[0078] 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 61 for controlling the thermal conditioning system 100.

[0079] 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".

[0080] The thermal conditioning system 100 may comprise one or more heat transfer liquid circuits. These heat transfer liquid circuits also form one or more closed and sealed circuits in which a heat transfer liquid can circulate.

[0081] [Fig.l] shows a thermal conditioning system 100 for a motor vehicle, according to a first embodiment. The thermal conditioning system 100 comprises a refrigerant 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 an interior air flow Fi 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 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, The thermal conditioning system 100 comprises an electronic control unit 61 configured to implement the method which will be described in detail below.

[0082] 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.

[0083] 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 fluid 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 fluid so as to supply the compressor 7 with refrigerant fluid in gaseous form.

[0084] The thermal coupling between the first heat exchanger 1 and the interior air flow Fi can be ensured in different ways.

[0085] According to the illustrated example, the first heat exchanger 1 is configured to exchange heat with the interior air flow Fi in the passenger compartment of the vehicle.

[0086] The thermal coupling between the first heat exchanger 1 and the interior air flow Fi is said to be direct. Indeed, the interior air flow Fi 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.

[0087] 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 interior air flow Fi in the passenger compartment of the vehicle.

[0088] The thermal coupling between the first heat exchanger 1 and the interior air flow Fi is in this case said to be 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.

[0089] The second exchanger 2 is for example arranged in the front face of the vehicle, in order to directly receive the external air flow Fe. The second exchanger 2 is for example arranged behind the grille of the vehicle.

[0090] 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.

[0091] [Fig.2] illustrates a second embodiment of the thermal conditioning system 100. This embodiment differs from the first embodiment by the presence of additional elements.

[0092] 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 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 the interior air flow Fi. 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.

[0093] The fourth exchanger 4 is arranged in the heating, ventilation and / or air conditioning installation of the vehicle. The fourth exchanger 4 is arranged upstream of the first exchanger 1 in a direction of flow of the interior air flow Fi.

[0094] The second branch of derivation C comprises a sixth regulator 36 arranged between the seventh connection point 17 and the fourth connection point 14.

[0095] 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.

[0096] 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.

[0097] 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.

[0098] 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.

[0099] 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 non-return valve is a passive member reacting to the pressure difference existing between its inlet and its outlet. No electrical control is necessary.

[0100] The main loop A comprises a first stop valve 41 arranged between the first connection point 11 and the first heat exchanger 1. 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 fluid through the expansion valve is zero.

[0101] The main loop A comprises a second shut-off valve 42 arranged 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 arranged between the second connection point 12 and the sixth connection point 16.

[0102] The first shut-off valve 41 is an electrically controlled valve. Similarly, the second shut-off valve 42 is an electrically operated valve.

[0103] Depending on the operating mode, 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 electric powertrain of the vehicle can thus be maintained, or placed, in a preferred temperature range corresponding to the optimal operation of this element.

[0104] According to an exemplary embodiment, the element 25 of the electric traction chain 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.

[0105] According to the example illustrated, 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.

[0106] 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 traction chain of the vehicle. The heat transfer fluid thus allows a heat transfer between the refrigerant fluid and the 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.

[0107] 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 fourth bypass branch E comprises a seventh expansion valve 37.

[0108] 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 com presser 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 of refrigerant fluid supplied by the compressor 7 and thus increase the thermal heating power supplied by the refrigerant fluid.

[0109] Each regulator 31, ..37 is for example an electronic regulator.

[0110] The first branch of derivation B, the second branch of derivation C, the third branch of derivation D 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. Additionally, the fourth branch E may or may not be present when the second branch C is present. Similarly, the fifth branch F may or may not be present when the second branch C is present.

[0111] The thermal conditioning system 100 can operate according to several operating modes. The proposed method, when implemented, corresponds to a particular operating mode of the thermal conditioning system 100.

[0112] 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 an interior air flow Fi 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 main loop A comprising an internal exchanger 6 configured to allow heat exchange between the refrigerant circulating between the first expander 31 and the second expander 32 and the refrigerant downstream of the accumulation device 8 and upstream of an inlet 7a of the compressor 7, 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 internal exchanger 6, (v) expanding the refrigerant fluid coming from the internal exchanger 6 to a low pressure lower than the intermediate pressure, (vi) circulating the refrigerant at low pressure in the second exchanger 2.

[0113] The refrigerant transfers heat to the interior air flow Fi at the first exchanger 1, and absorbs heat from the exterior air flow at the second exchanger 2. The passenger compartment of the vehicle can thus be heated by recovering energy from the exterior air flow. After having transferred heat to the interior air flow Fi, the high-pressure refrigerant undergoes two successive expansions, first in the first expansion valve 31 and then in the second expansion valve 32. The intermediate-pressure refrigerant, after the first of the two expansions, carries out in the internal exchanger 6 a heat exchange with the low-pressure refrigerant coming from the second exchanger 2 and returning to the inlet 7a of the compressor 7. The efficiency of the internal exchanger 6 can be controlled by controlling the value of the intermediate pressure, by adjusting the flow section of the refrigerant in the first expansion valve 31.The inlet temperature of the refrigerant fluid in the compressor 7 can thus be adjusted, which also makes it possible to adjust the discharge temperature at the outlet of the compressor 7. The thermomechanical stresses undergone by the parts of the compressor are thus reduced, which makes it possible to avoid premature degradation of the compressor 7 under the most severe conditions. In addition, limiting the discharge temperature at the outlet of the compressor 7 also makes it possible to limit the inlet temperature of the refrigerant at the inlet of the first exchanger 1. The temperature difference of the refrigerant between the inlet 1a and the outlet 1b of the first exchanger 1 is thus reduced. The temperature gradient of the interior air flow Fi along the direction of flow of the refrigerant is thus reduced. Passenger comfort is improved, because the air blown into the passenger compartment can be of a more uniform temperature. Indeed, since the refrigerant is less hot near the outlet 1b than near the inlet 1a, the part of the interior air flow Fi passing through the first exchanger 1 in an area close to the inlet 1a leaves at a higher temperature than the part of the interior air flow passing through the first exchanger 1 in an area close to the outlet 1b.This temperature gradient in the air flow Fi leaving the first exchanger 1 is particularly marked when the refrigerant is in a supercritical state. The temperature gradient exists. also when the refrigerant is in a two-phase state, due to the phenomenon of desuperheating in the first exchanger 1, and due to subcooling when the operating conditions make subcooling possible.

[0114] According to the proposed method, the first exchanger 1 operates as a refrigerant fluid cooler. According to the proposed method, the second exchanger 2 operates as a refrigerant fluid evaporator. According to other operating modes, not illustrated, the second exchanger 2 can operate selectively as a refrigerant fluid condenser or as a refrigerant fluid evaporator.

[0115] The fourth exchanger 4 can operate as a refrigerant fluid evaporator. The fifth expander 35 is configured to expand the refrigerant circulating between the main loop A and an inlet of the fourth exchanger 4.

[0116] The fourth exchanger 4 is arranged upstream of the first exchanger 1 in a direction of flow of the interior air flow Fi. The fourth exchanger 4 allows the indoor air flow Fi to be cooled, and the first exchanger 1 allows the indoor air flow Fi to be heated. The indoor air flow can thus be dehumidified in certain operating modes.

[0117] The first expansion valve 31 is configured to expand the refrigerant fluid between an outlet of the first exchanger 1 and an inlet of the first heat exchange section 6a of the internal exchanger 6. The refrigerant fluid coming from the first exchanger 1 is expanded to an intermediate pressure by passing through the first expansion valve 31. The refrigerant fluid expanded to an intermediate pressure reaches an inlet of the first heat exchange section 6a of the internal exchanger 6.

[0118] The second expansion valve 32 is configured to expand the refrigerant fluid between an outlet of the first heat exchange section 6a of the internal exchanger 6 and an inlet of the second exchanger 2. The refrigerant fluid coming from the first heat exchange section 6a of the internal exchanger 6 is expanded to a low pressure by passing through the second expansion valve 32. The refrigerant fluid expanded to a low pressure then reaches an inlet of the second exchanger 2.

[0119] [Fig.3] illustrates the circulation of the refrigerant fluid in the circuit 10 when the proposed method is implemented on a thermal conditioning system 100 according to the second embodiment, the architecture of which is illustrated in [Fig.2]. The portions of the circuit 10 in which a flow of refrigerant fluid circulates are in a continuous thick line, while the portions in which the refrigerant fluid does not do not circulate are in fine dotted lines.

[0120] A method for controlling a thermal conditioning system 100 is thus proposed, in which the refrigerant circuit 10 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, - a second branch 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 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 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 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 D successively comprising a fifth expansion valve 35 and a fourth heat exchanger 4 configured to exchange heat with the interior air flow Fi, - 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, in which the second branch C comprises a sixth regulator 36 arranged between the seventh connection point 17 and the fourth connection point 14, and in which: - the third regulator 33, the fourth regulator 34, the fifth regulator 35 and the sixth regulator 36 are jointly in the closed position.

[0121] The third regulator 33 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. The first branch of bypass B is not crossed by the refrigerant fluid.

[0122] The fourth regulator 34 is in the closed position. Thus, the third exchanger 3 does not participate in the heat exchanges.

[0123] The fifth expansion valve 35 is in the closed position. Thus, the fourth exchanger 4 does not participate in the heat exchanges.

[0124] According to the example illustrated, the sixth expansion valve 36 is in the closed position. Thus, the entire flow of refrigerant fluid passing through the second exchanger 2 reaches the accumulator 8 without being redirected to the fourth bypass branch E.

[0125] The second bypass branch C is not traversed by the refrigerant fluid.

[0126] The value of the so-called “high pressure” pressure, at the outlet of the compressor 7, is for example between 50 bars and 120 bars. The value of the so-called “intermediate” pressure, after expansion by the first regulator 31, is lower than the value of the high pressure. The intermediate pressure is, for example, between 30 bars and 70 bars. The value of the so-called “low pressure”, after expansion by the second regulator 32, is lower than the value of the intermediate pressure. Low pressure is for example between 10 bars and 35 bars.

[0127] A flow rate Q of high-pressure refrigerant fluid is supplied by the compressor 7. The high-pressure refrigerant fluid reaches the first connection point 11. The first stop valve 41 is in the open position, and the third expansion valve 33 is in the closed position. The entire flow rate Q of refrigerant fluid therefore circulates in the main loop A, passes through the first stop valve 41, and passes through the first exchanger 1, giving off heat to the interior air flow Fi. The first expansion valve 31 is in the partially open position and the fourth expansion valve 34 is in the closed position. At the third connection point 13, the high-pressure refrigerant flows through the main loop A, undergoes expansion in the first expansion valve 31 to an intermediate pressure, and then reaches the fifth connection point 15. The fifth regulator 35 is in the closed position, therefore the third bypass branch D is not crossed by refrigerant fluid. The seventh regulator 37 is in the closed position, and the fifth bypass branch F is not traversed by refrigerant fluid. The second expansion valve 32 is in the partially open position. The intermediate pressure refrigerant thus flows through the first heat exchange section 6a of the internal exchanger 6, then undergoes expansion in the second expansion valve 32 and passes to low pressure. The refrigerant evaporates in the second exchanger 2 by absorbing heat from the outside air flow Fe. The second shut-off valve 42 is in the open position. The low pressure refrigerant from the second exchanger 2 reaches the sixth connection point 16, then circulates in the accumulation device 8, in the second heat exchange section 6b of the exchanger internal 6, and returns to inlet 7a of compressor 7, thus completing the thermodynamic cycle. The first heat exchange section 6a of the internal exchanger 6 is traversed by refrigerant at intermediate pressure and the second heat exchange section 6b is traversed by refrigerant at low pressure. For identical high pressure values ​​and identical low pressure values, the intermediate pressure can be adjusted by controlling the distribution between the expansion rate provided by the first expansion valve 31 and the expansion rate provided by the second expansion valve 32. The temperature of the refrigerant circulating in the second heat exchange section 6b can thus be controlled, which makes it possible to control the efficiency of the internal exchanger 6. Controlling the efficiency of the internal exchanger 6 makes it possible to control the inlet temperature of the compressor 7 and hence the outlet temperature of the compressor 7.

[0128] According to one aspect of the proposed method, the temperature of the interior air flow Fi at the outlet of the first exchanger 1 is controlled by acting on the flow rate of refrigerant fluid discharged by the compressor 7.

[0129] The control method thus proposed comprises the steps: - receive a temperature setpoint Tc_l of the interior air flow Fi at the outlet of the first exchanger 1, - determine a temperature Tl of the interior air flow Fi at the outlet of the first exchanger 1, - controlling a flow rate of refrigerant fluid in the refrigerant fluid circuit 10 so that the determined temperature Tl of the interior air flow Fi at the outlet of the first exchanger 1 is equal to the temperature setpoint Tc_l.

[0130] The temperature of an air flow leaving a heat exchanger is understood to mean the temperature of this air flow after having carried out a heat exchange with the refrigerant fluid circulating in this heat exchanger.

[0131] The temperature Tl of the interior air flow Fi at the outlet of the first exchanger 1 can for example be determined by a measuring sensor arranged in the interior air flow Fi, close to the first exchanger 1 and downstream of the latter in a direction of flow of the interior air flow Fi. According to alternative embodiments, the temperature Tl of the interior air flow Fi at the outlet of the first exchanger 1 can be determined from a temperature measurement carried out at another point of passage of the interior air flow Fi and from a model of temperature evolution between the point where the measurement is carried out and the outlet of the first exchanger 1 for the interior air flow Fi. The temperature measurement sensor has not been shown in the figures.

[0132] 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.

[0133] In the case of an electric compressor, the rotation speed of the compressor is controlled by modulating the electric current supplied to the electric motor of the compressor 7.

[0134] 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.

[0135] The control method comprises the sub-step: - increase the rotation speed of compressor 7 when the determined temperature Tl of the interior air flow Fi is lower than the set temperature Tc_l. By increasing the rotation speed of the compressor 7, the refrigerant flow rate increases, as does the thermal power supplied to the first exchanger 1 which operates as a refrigerant cooler. The temperature of the interior air flow Fi, after heat exchange with the refrigerant at the first exchanger 1, tends to approach its set value Tc_l.

[0136] Similarly, the control method comprises the sub-step: - reduce the rotation speed of compressor 7 when the determined temperature Tl of the interior air flow Fi is higher than the set temperature Tc_l. By reducing the rotation speed of the compressor 7, the refrigerant flow rate decreases, as does the thermal power supplied to the first exchanger 1. The temperature of the interior air flow Fi, after heat exchange with the first exchanger 1, tends to approach its set value. Regulation of the rotation speed of the compressor 7 thus makes it possible to regulate the temperature Tl of the interior air flow Fi.

[0137] The control method comprises 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 second expansion valve 32 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.

[0138] The control method thus comprises the sub-step: - reduce a passage section of the refrigerant fluid through the second expansion valve 32 if the determined pressure P_c of the refrigerant fluid at the outlet of the compressor 7 is lower than a target value.

[0139] The control method further comprising the sub-step: - increasing a passage section of the refrigerant fluid through the second expansion valve 32 if the determined pressure P_c of the refrigerant fluid at the outlet of the compressor 7 is greater than a target value.

[0140] Regulation of the passage section of the refrigerant fluid through the second expansion valve 32 thus makes it possible to regulate the pressure of the refrigerant fluid at the outlet of the compressor 7.

[0141] The control method may comprise the steps: - determine a maximum admissible temperature Tmax of the refrigerant fluid at the outlet of the compressor 7, - determine a temperature T_c of the refrigerant fluid at the outlet of the compressor 7, - control an expansion of the refrigerant fluid in the first expansion valve 31 so that the determined temperature T_c is lower than the maximum temperature Tmax.

[0142] The proposed control method thus comprises the sub-step: - reduce a passage section of the refrigerant fluid through the first expansion valve 31 if the determined temperature T_c of the refrigerant fluid at the outlet of the compressor 7 is higher than a target value.

[0143] The proposed control method further comprises the sub-step: - increase a passage section of the refrigerant fluid through the first expansion valve 31 if the determined temperature T_c of the refrigerant fluid at the outlet of the compressor 7 is lower than a target value.

[0144] Regulation of the passage section of the refrigerant fluid through the first expansion valve 31 thus makes it possible to regulate the temperature of the refrigerant fluid at the outlet of the compressor 7.

[0145] The simultaneous adjustment of the rotation speed of the compressor 7, the passage section of the first expander 31 and the passage section of the second expander 32 makes it possible to simultaneously control the temperature of the interior air flow Fi, the discharge pressure of the compressor 7 and the discharge temperature of the compressor 7. The proposed type of control allows stable operation of the thermal conditioning system and a low response time when changes in setpoints or operating conditions occur.

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) successively comprising, according to the direction of circulation of the refrigerant: - a compressor (7), - a first heat exchanger (1) thermally coupled with an interior air flow (Fi) to a passenger compartment of the vehicle, - a first expansion valve (31), - a second expansion valve (32), - a second heat exchanger (2) configured to exchange heat with an exterior air flow (Fe) to the passenger compartment of the vehicle, - a refrigerant accumulation device (8),the main loop (A) comprising 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), the method comprising the successive steps: (i) providing a flow of high-pressure refrigerant at the outlet of the compressor (7), (ii) circulating high-pressure refrigerant in the first heat exchanger (1), (iii) expanding the high-pressure refrigerant coming from the first heat exchanger (1) to an intermediate pressure lower than the high pressure, (iv) circulating the intermediate-pressure refrigerant in the internal exchanger (6), (v) expanding the refrigerant coming from the internal exchanger (6) to a low pressure lower than the intermediate pressure,(vi) circulating the refrigerant at low pressure in the second exchanger (2).,

2. Control method according to the preceding claim, in which the refrigerant circuit (10) comprises: - a first bypass branch (B) connecting a first connection point (11) arranged on the main loop (A) downstream of an outlet

3. (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 second pressure reducer (32) 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 the interior air flow (Fi), - 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), 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 third regulator (33), the fourth regulator (34), the fifth regulator (35) and the sixth regulator (36) are jointly in the closed position. Control method according to claim 1 or 2, comprising the steps: - receive a temperature setpoint (Tc_l) from the interior air flow (Fi) at the outlet of the first exchanger (1), - determine a temperature (Tl) of the interior air flow (Fi) at the outlet of the first exchanger (1), - control a flow rate of refrigerant fluid in the refrigerant circuit (10) so that the determined temperature (Tl) of the interior air flow (Fi) at the outlet of the first exchanger (1) is equal to the temperature setpoint (Tc_l).

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

5. Control method according to the preceding claim, comprising the sub-steps: - increasing the rotation speed of the compressor (7) when the determined temperature (Tl) of the interior air flow (Fi) is lower than the set temperature (Tc_l), - decreasing the rotation speed of the compressor (7) when the determined temperature (Tl) of the interior air flow (Fi) is higher than the set temperature (Tc_l).

6. Control method according to one of the preceding claims, comprising the steps: - determining a maximum admissible pressure (Pmax) of the refrigerant fluid at the outlet of the compressor (7), - determining a pressure (P_c) of the refrigerant fluid at the outlet of the compressor (7), - controlling an expansion of the refrigerant fluid in the second expansion valve (32) 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).

7. Control method according to the preceding claim, comprising the sub-steps: - reducing a passage section of the refrigerant fluid through the second expansion valve (32) if the determined pressure (P_c) of the refrigerant fluid at the outlet of the compressor (7) is lower than a target value, - increasing a passage section of the refrigerant fluid through the second expansion valve (32) if the determined pressure (P_c) of the refrigerant fluid at the outlet of the compressor (7) is higher than a target value.

8. Control method according to one of the preceding claims, comprising the steps: - determining a maximum admissible temperature (Tmax) of the refrigerant fluid at the outlet of the compressor (7), - determining a temperature (T_c) of the refrigerant fluid at the outlet of the compressor (7), - controlling an expansion of the refrigerant fluid in the first expansion valve (31) so that the determined temperature (T_c) is lower than the maximum temperature (Tmax).

9. Control method according to the preceding claim, comprising the sub-steps: - reducing a passage section of the refrigerant fluid through the first expansion valve (31) if the determined temperature (T_c) of the refrigerant fluid at the outlet of the compressor (7) is higher than a target value, - increasing a passage section of the refrigerant fluid through the first expansion valve (31) if the determined temperature (T_c) of the refrigerant fluid at the outlet of the compressor (7) is lower than a target value.

10. Thermal conditioning system for a motor vehicle, comprising a refrigerant circuit (10) comprising: - A main loop (A) successively comprising, according to the direction of circulation of the refrigerant: — a compressor (7), — a first heat exchanger (1) thermally coupled with an interior air flow (Fi) to a passenger compartment of the vehicle, — a first expansion valve (31), — a second expansion valve (32), — a second heat exchanger (2) configured to exchange heat with an exterior air flow (Fe) to the passenger compartment of the vehicle, — a refrigerant accumulation device (8), the main loop (A) comprising 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),- an electronic control unit (61) configured to implement the method according to one of the preceding claims.,

11. Thermal conditioning system (100) according to the preceding claim, comprising: - a first branch branch (B) connecting a first connection point- connection (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 branch 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 second expansion valve (32) 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 expansion valve (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 the interior air flow (Fi), - 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).

12. Thermal conditioning system (100) according to the preceding claim, comprising: - A fifth branch 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 branch branch (C) downstream of the fourth regulator (34) and upstream of the seventh connection point (17), the fourth branch branch bypass (E) comprising a seventh regulator (37).

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