Method for controlling a thermal conditioning system for a motor vehicle

Abstract

The invention relates to a method for controlling a thermal conditioning system for a motor vehicle, comprising a refrigerant circuit (10) comprising: - a main loop (A) comprising: -- a compressor (7), -- a first heat exchanger (1), -- a first expansion device (31), -- a second expansion device (32), -- a second exchanger (2), - a first bypass branch (B) comprising a third expansion device (33), - a second bypass branch (C) comprising a third exchanger (3), the method comprising the steps: (ii) circulating high-pressure refrigerant in the first exchanger (1) and in the first bypass branch (B), (iv) expanding at least part of the refrigerant coming from the first exchanger (1) to a low pressure, and circulating it in the second exchanger (2), (vi) expanding the refrigerant in the first bypass branch (B) and mixing it with the refrigerant coming from the second exchanger (2).

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 makes it possible to limit to a minimum the global warming potential (GWP coefficient) of the refrigerant used. Various thermal conditioning systems adapted to operate with carbon dioxide as a 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 and cooling it, as well as heating and cooling the electrical energy storage batteries. [3] According to a so-called heat pump operating mode, the high-pressure refrigerant transfers heat to the air supplying the vehicle's passenger compartment at a first heat exchanger, then is expanded to a low-pressure state. The low-pressure refrigerant is evaporated in a second exchanger by receiving heat from an outside air flow. This outside air flow is therefore cooled by passing through the second exchanger. When the ambient temperature is negative or close to 0°C, the water vapor contained in the outside air is likely to frost and accumulate on the second exchanger. The heat exchange is then degraded, and the thermal power likely to be supplied to the passenger compartment decreases as ice accumulates. Operation according to this so-called heat pump mode may become impossible. It may then become necessary to use electric heating, which increases energy consumption. [4] It is therefore desirable to be able to heat the passenger compartment of the vehicle while avoiding causing icing of the heat exchanger recovering heat from the outside air. Summary [5] For this purpose, a method is proposed for controlling a thermal conditioning system for a motor vehicle, the thermal conditioning system comprising a refrigerant circuit comprising: A main loop comprising successively according to 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 circulating downstream of the accumulation device and upstream of a compressor inlet, A first bypass 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 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 first 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 powertrain of a motor vehicle, A third branch connection connecting a fifth connection point arranged on the second branch downstream of the third exchanger and upstream of the fourth connection point to a sixth connection point arranged on the main loop between the first regulator and the second regulator, A fourth branch branch connecting a seventh connection point arranged on the main loop downstream of the first connection point and upstream of the first exchanger to an eighth connection point arranged on the second branch branch downstream of the fourth regulator and upstream of the third exchanger, the fourth branch branch comprising a fifth regulator, the method comprising the steps: (i) provide a first flow of high-pressure refrigerant fluid at the compressor outlet, (ii) splitting the first flow of high-pressure refrigerant into a second flow circulating in the main loop and a third flow circulating in the first bypass branch, (iii) circulating at least a portion of the second flow of high-pressure refrigerant fluid through the first heat exchanger, (iv) expanding at least a portion of the high pressure refrigerant from the first heat exchanger to a low pressure, (v) circulating the refrigerant at low pressure in the second exchanger, (vi) expanding the third flow to low pressure so that the third flow joins the refrigerant coming from the second exchanger so as to form the first flow, the first flow of low pressure refrigerant joining the compressor. [6] In the proposed method, the thermal energy taken from the outside air flow at the second exchanger contributes to heating the passenger compartment of the vehicle at the first exchanger. The flow of refrigerant circulating in the first branch makes it possible to complete the thermodynamic cycle while limiting the quantity of heat extracted from the outside air flow. The risks of icing of the second exchanger are thus reduced, without limiting the thermal power supplied to the passenger compartment. [7] The features listed in the following paragraphs may be implemented independently of each other or in any technically possible combination: [8] The refrigerant circuit is configured to circulate a refrigerant. [9] The compressor moves the refrigerant fluid from a low pressure state, at the compressor inlet, to a high pressure state, at the compressor outlet.

[0010] 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.

[0011] According to an alternative embodiment, the first heat exchanger is configured to exchange heat with a heat transfer fluid circulating in a heat transfer fluid circuit, the heat transfer fluid circuit comprising a heat exchanger configured to exchange heat with the air flow inside the passenger compartment of the vehicle.

[0012] According to the proposed method, the first exchanger operates as a refrigerant fluid cooler.

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

[0014] According to the proposed method, the third exchanger can operate as a refrigerant cooler.

[0015] The third heat exchanger is used to heat the vehicle's electric powertrain element. 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.

[0016] According to an exemplary embodiment, the element of the electric powertrain of the vehicle comprises an electrical energy storage battery.

[0017] Alternatively or additionally, the element of the vehicle's electric powertrain comprises an electric vehicle traction motor.

[0018] Alternatively or additionally, the element of the electric traction chain of the vehicle comprises an electronic unit for controlling the electric traction motor of the vehicle.

[0019] 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.

[0020] According to one embodiment, the second branch branch comprises a sixth regulator arranged between the fourth connection point and the fifth connection point.

[0021] Each regulator is for example an electronic regulator.

[0022] 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 a compressor inlet. The internal exchanger, also called internal heat exchanger, is configured to allow heat exchange between the refrigerant in the first heat exchange section and the refrigerant in the second heat exchange section.

[0023] According to a first example of implementation of the method, the refrigerant fluid coming from the first exchanger circulates in the first expansion valve where it passes at intermediate pressure, in the internal exchanger, then in the second expansion valve where it passes at low pressure. According to this first example of implementation, the flow rate of refrigerant circulating in the second exchanger is equal to the flow rate of refrigerant circulating in the first exchanger.

[0024] The value of the so-called “high pressure” pressure, at the outlet of compressor 7, is for example between 40 bars and 130 bars. The value of the so-called “intermediate” pressure, after expansion for example by the first regulator 31, is lower than the value of the high pressure. The intermediate pressure is for example between 20 bars and 70 bars. The value of the so-called “low pressure”, after expansion for example in the second regulator 32, is lower than the value of the intermediate pressure. Low pressure is for example between 10 bars and 40 bars.

[0025] According to this first example of implementation of the process: - The first regulator is in the partially open position. - The second regulator is in the partially open position. - The third regulator is in the partially open position. - The fourth regulator is in the closed position. - The fifth regulator is in the closed position. - The sixth regulator is in the closed position.

[0026] According to a second example of implementation of the method, the second flow of high-pressure refrigerant fluid circulates in the first exchanger and is divided into a first part circulating in the main loop and a second part circulating in the second branch branch. The refrigerant flowing in the second bypass branch flows into the fourth expansion valve where it passes at low pressure, and the low-pressure refrigerant from the third exchanger joins the low-pressure refrigerant from the second exchanger and the first bypass branch.

[0027] In this second implementation example, the low-pressure refrigerant circulating in the third exchanger recovers the heat dissipated by the thermal losses of the vehicle's electric powertrain element. Energy efficiency is thus improved.

[0028] According to this second example of implementation of the process: - The first regulator is in the partially open position. - The second regulator is in the partially open position. - The third regulator is in the partially open position. - The fourth regulator is in the partially open position. - The fifth regulator is in the closed position. - The sixth regulator is in the fully open position.

[0029] According to a third example of implementation of the method, the second flow of high-pressure refrigerant fluid circulating in the main loop is divided into a first part circulating in the first exchanger then in the second bypass branch, and a second part complementary to the first part circulating in the fourth bypass branch, the first part and the second part joining upstream of the third exchanger and forming the second flow, the second flow circulating successively in the third exchanger, in the second bypass branch, in the third bypass branch, in the second expansion valve, in the second exchanger, the second flow joining the third flow and forming the first flow, the first flow joining the compressor.

[0030] The high-pressure refrigerant circulating in the main loop heats the interior airflow and thus the vehicle's passenger compartment. The refrigerant circulating in the fourth branch joins the refrigerant from the first exchanger, and the resulting mixture, by releasing heat in the third exchanger, heats the vehicle's powertrain element.

[0031] According to the third example of implementation of the process: - the refrigerant fluid coming from the first exchanger is expanded by the fourth expansion valve to an intermediate pressure lower than the high pressure, - the refrigerant fluid circulating in the fourth bypass branch is expanded by the fifth expansion valve to the intermediate pressure, and - the refrigerant fluid circulating in the third bypass branch is expanded by the second expansion valve to a low pressure lower than the intermediate pressure.

[0032] According to this third example of implementation of the process: - The first regulator is in the closed position. - The second regulator is in the partially open position. - The third regulator is in the partially open position. - The fourth regulator is in the partially open position. - The fifth regulator is in the partially open position. - The sixth regulator is in the closed position.

[0033] According to a particular case of the third example of implementation of the process: - a flow rate of refrigerant circulating in the fourth bypass branch is lower than a first predefined threshold, - an indoor airflow rate is lower than a second predefined threshold.

[0034] The refrigerant flow rate circulating in the fourth bypass branch may be zero. The indoor airflow rate may be zero.

[0035] The proposed control method may include 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.

[0036] When the first heat exchange section of the internal exchanger is crossed by refrigerant, controlling the value of the refrigerant pressure in the first heat exchange section makes it possible to control the efficiency of the internal exchanger, i.e. the quantity of heat exchanged between the first heat exchange section and the second heat exchange section. It is thus possible to adjust the temperature at the compressor inlet, and therefore also the discharge temperature. at the compressor outlet. The compressor discharge temperature can thus be maintained at a value lower than or equal to a maximum permissible temperature.

[0037] The control process can thus include the following sub-steps: - 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 first target value, - 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 the first target value.

[0038] The proposed control method may include the steps: - determine the pressure of the refrigerant fluid at the compressor outlet, - 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 greater than a second target value, - 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 the second target value.

[0039] The control process may include the following sub-steps: - controlling the flow rate of refrigerant discharged by the compressor and controlling a section of passage of the refrigerant through the third expansion valve so as to control the pressure of the refrigerant in the second exchanger at a value greater than a predefined minimum threshold and so as to control at a third target value the thermal power supplied by the first exchanger.

[0040] The expansion level applied by the third expansion valve allows, in combination with the flow rate provided by the compressor, to control the low pressure value of the thermodynamic cycle as well as the heating power provided by the first exchanger, i.e. that provided by the first exchanger. By controlling the low pressure to a sufficiently high value, the thermal power absorbed by the second exchanger is limited, which prevents the second exchanger from icing in a cold environment.

[0041] The value of the predefined minimum pressure threshold may depend on the ambient temperature.

[0042] The control process may include the step: - control the compressor rotation speed in order to control the refrigerant flow in the refrigerant circuit.

[0043] The control process includes the following steps: - increase the compressor rotation speed so as to increase the total flow rate circulating in the refrigerant circuit, and - reduce the compressor rotation speed so as to reduce the total flow circulating in the refrigerant circuit.

[0044] The control process may include the following sub-steps: - determine overheating of the refrigerant fluid at the outlet of the third exchanger, - control a section of passage of the refrigerant fluid through the fourth expansion valve so as to adjust the superheating of the refrigerant fluid at the outlet of the third exchanger to a fourth target value.

[0045] The control process may include the following sub-steps: - increase a passage section of the refrigerant fluid through the fourth expansion valve if the determined superheat of the refrigerant fluid at the outlet of the third exchanger is greater than the fourth target value, - reduce a passage section of the refrigerant fluid through the fourth expansion valve if the determined superheat of the refrigerant fluid at the outlet of the third exchanger is lower than the fourth target value.

[0046] The control process may include the steps: - determine a thermal power supplied by the third exchanger to the element of the traction chain, - control a section of passage of the refrigerant fluid through the fifth expansion valve so as to adjust the thermal power supplied by the third exchanger to a fifth target value.

[0047] The thermal power supplied by the third exchanger to the element of the traction chain is for example determined from the value of the flow rate of heat transfer fluid in the circuit, and from the value of the temperature difference of the heat transfer fluid between the inlet and the outlet of the third exchanger.

[0048] The control process may include the following sub-steps: - increase a passage section of the refrigerant fluid through the fifth expansion valve if the thermal power supplied by the third exchanger is lower than the fifth target value, - reduce a refrigerant fluid passage section through the fifth expansion valve if the thermal power supplied by the third exchanger is lower than the fifth target value.

[0049] The control process may include the steps: - receive 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 section of passage of the refrigerant fluid in the fourth expansion valve so that the determined temperature of the interior air flow at the outlet of the first exchanger is equal to the temperature setpoint.

[0050] The control process may include the following sub-steps: - increase a passage section of the refrigerant fluid through the fourth expansion valve if the determined temperature of the interior air flow at the outlet of the first exchanger is lower than the temperature setpoint, and - reduce a passage section of the refrigerant fluid through the fourth expansion valve if the determined temperature of the interior air flow at the outlet of the first exchanger is higher than the temperature setpoint.

[0051] When the air flow rate through the first exchanger is low or even zero, the heat exchange carried out by the first exchanger is negligible or zero. The refrigerant only heats the heat transfer fluid circulating in the circuit 40 coupled to the third exchanger. The circulation of refrigerant through the first exchanger ensures a return of the oil to the compressor and prevents an accumulation of this oil in the first exchanger.

[0052] In this operating mode corresponding to the third example of implementation of the process: - the first regulator is in the closed position. - the sixth regulator is in the closed position. - the second regulator, the third regulator, the fourth regulator, and the fifth regulator are in the partially open position.

[0053] A thermal conditioning system for a motor vehicle is also proposed, comprising a refrigerant circuit comprising: a main loop comprising successively, depending on the direction of circulation of the refrigerant: -- 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 circulating downstream of the accumulation device and upstream of an inlet of the compressor, a first bypass 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 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 first 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 powertrain of a motor vehicle, a third branch connecting a fifth connection point arranged on the second branch downstream of the third exchanger and upstream of the fourth connection point to a sixth connection point arranged on the main loop between the first expansion valve and the second expansion valve,a fourth branch branch connecting a seventh connection point arranged on the main loop downstream of the first connection point and upstream of the first exchanger to an eighth connection point arranged on the second branch branch downstream of the fourth regulator and upstream of the third exchanger, the fourth branch branch comprising a fifth regulator, - an electronic control unit configured to implement the method described above.

[0054] According to one embodiment, the thermal conditioning system comprises: - A fifth branch branch connecting a ninth connection point arranged on the main loop between the first expansion valve and the sixth connection point to a tenth connection point arranged on the main loop between the second connection point and the fourth connection point, the fifth branch branch successively comprising a seventh expansion valve and a fourth heat exchanger configured to exchange heat with an interior air flow.

[0055] The fourth exchanger is arranged upstream of the first exchanger according to the direction of flow of the interior air.

[0056] When the fifth bypass branch is present, the internal exchanger is configured to allow heat exchange between the refrigerant circulating between the ninth connection point and the sixth connection point and the refrigerant circulating downstream of the accumulation device and upstream of a compressor inlet.

[0057] The main loop includes a first shutoff valve disposed between the first connection point and the seventh connection point.

[0058] The main loop includes a second shutoff valve located between the second connection point and the fourth connection point.

[0059] The main loop includes a second shut-off valve located between the second connection point and the tenth connection point.

[0060] The first shut-off valve is an electrically operated valve. Similarly, the second shut-off valve is an electrically operated valve.

[0061] The refrigerant circuit comprises a first one-way valve arranged on the main loop between the first exchanger and the third connection point.

[0062] The first one-way valve is configured to allow circulation of refrigerant fluid through the first one-way valve from the first exchanger to the third connection point. The first one-way valve is also configured to prohibit circulation of refrigerant fluid through the first one-way valve from the third connection point to the first exchanger.

[0063] The refrigerant circuit includes a second one-way valve arranged on the third bypass branch.

[0064] The second one-way valve is configured to allow refrigerant fluid flow through the second one-way valve from the fifth connection point to the sixth connection point and configured to prohibit refrigerant fluid flow through the second one-way valve from the sixth connection point to the fifth connection point.

[0065] The refrigerant circuit includes a third one-way valve located on the main loop between the fourth exchanger and the tenth connection point.

[0066] The third one-way valve is configured to allow refrigerant fluid to circulate through the third one-way valve of the fourth exchanger to the tenth connection point.

[0067] The third one-way valve is also configured to prohibit a circulation of refrigerant fluid through the third one-way valve of the tenth connection point towards the fourth exchanger.

[0068] The first one-way valve is for example a check valve.

[0069] Similarly, the second one-way valve and the third one-way valve can also be a check valve.

[0070] Alternatively, each one-way valve may be an electrically operated valve.

[0071] The disclosure also relates to a computer program stored in a memory and configured to implement the method described above. Brief description of the drawings

[0072] Other features, details and advantages will become apparent upon reading the detailed description below, and upon analyzing the attached drawings, in which:

[0073] [Fig. 1] is a schematic view of a thermal conditioning system according to a first embodiment of the invention,

[0074] [Fig. 2] is a schematic view of a thermal conditioning system according to a second embodiment of the invention,

[0075] [Fig. 3] is a schematic view illustrating the operation of the thermal conditioning system of Figure 2, according to a first example of implementation of the proposed method,

[0076] [Fig. 4] is a schematic view illustrating the operation of the thermal conditioning system of Figure 2, according to a second example of implementation of the proposed method,

[0077] [Fig. 5] is a schematic view illustrating the operation of the thermal conditioning system of Figure 2, according to a third example of implementation of the proposed method,

[0078] [Fig. 6] is a block diagram of the proposed process. Description of the embodiments

[0079] To facilitate reading the figures, the different elements are not necessarily represented to scale. In these figures, identical elements have 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 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.

[0080] 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.

[0081] 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.

[0082] When it is specified that a subsystem includes a given element, this does not exclude the presence of other elements in this subsystem.

[0083] The thermal conditioning system 100 which will be described comprises an electronic control unit 62 receiving information from various sensors measuring in particular the characteristics of the refrigerant fluid at various points in the circuit. The electronic control unit 62 also receives instructions issued by the occupants of the vehicle, for example the desired temperature inside the passenger compartment. The electronic control unit 62 can also receive instructions from other electronic subsystems, such as a system for managing electrical energy storage batteries. The electronic control unit 62 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 62 can execute software encoding the proposed method.

[0084] 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.

[0085] 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 done 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 allow to selectively direct the refrigerant fluid into the different branches of the refrigerant circuit, in order to ensure different modes of operation, as will be described later.

[0086] The refrigerant used by the refrigerant circuit 10 is a natural refrigerant, such as R744. It is also possible to use a chemical refrigerant, such as R1234yf, or R134a.

[0087] 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.

[0088] 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, also 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.

[0089] 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.

[0090] The term "first exchanger" is equivalent to the term "first heat exchanger". Similarly, the term "internal exchanger" is equivalent to the term "exchanger internal heat". The term "accumulation device" is equivalent to the term "refrigerant fluid accumulation device".

[0091] 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.

[0092] Figure 1 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 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 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 circulating downstream of the accumulation device 8 and upstream of an inlet 7a of the compressor 7. The refrigerant circuit 10 comprises: a first branch 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 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 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 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 second branch branch C downstream of the third exchanger 3 and upstream of the fourth connection point 14 to a sixth connection point 16 arranged on the main loop A between the first expansion valve 31 and the second expansion valve 32, a fourth branch branch E connecting a seventh connection point 17 arranged on the main loop A downstream of the first connection point 11 and upstream of the first exchanger 1 to an eighth connection point 18 arranged on the second branch branch C downstream of the fourth expansion valve 34 and upstream of the third exchanger 3, the fourth branch branch E comprising a fifth expansion valve 35. The thermal conditioning system 100 comprises an electronic control unit 62 configured to implement the method which will be described below.

[0093] A computer program stored in a memory can implement the proposed method. The memory can be integrated into the electronic control unit 62.

[0094] The refrigerant circuit 10 is configured to circulate a refrigerant. The compressor 7 passes the refrigerant 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. 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.

[0095] The thermal coupling between the first heat exchanger 1 and the indoor air flow Fi can be ensured in different ways.

[0096] According to the example of Figure 1, the first heat exchanger 1 is configured to exchange heat with a heat transfer fluid circulating in a heat transfer fluid circuit 30, the heat transfer fluid circuit 30 comprising a heat exchanger 1A configured to exchange heat with the interior air flow Fi in the passenger compartment of the vehicle.

[0097] A pump, not shown, allows the heat transfer fluid to circulate in the circuit 30. The circuit 30 forms a closed circuit. The circuit 30 is sealed during nominal operation of the thermal conditioning system 100, that is to say when the system is completely assembled and operating without fault. The heat transfer fluid circulating in the circuit 30 is, for example, a mixture of water and glycol.

[0098] 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 the heat transfer fluid of the circuit 30 which transfers the heat supplied by the refrigerant fluid to the air flow Fi supplying the passenger compartment of the vehicle. The heat exchanger 1A of the heat transfer fluid circuit, also called the heating radiator, is located in the vehicle's heating, ventilation and / or air conditioning system.

[0099] According to the example of Figure 2, the first heat exchanger 1 is configured to exchange heat with the interior air flow Fi to the passenger compartment of the vehicle.

[0100] The thermal coupling between the first heat exchanger 1 and the interior air flow Fi is in this case called 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.

[0101] 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 an 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. When the first heat exchange section 6a is not traversed by a flow of refrigerant fluid, there is no heat exchange in the internal exchanger 6.

[0102] The second embodiment of the thermal conditioning system 100, illustrated in FIG. 2, also differs from the first embodiment by the presence of an additional refrigerant circulation branch.

[0103] The thermal conditioning system 100 thus comprises a fifth bypass branch F connecting a ninth connection point 19 arranged on the main loop A between the first expansion valve 31 and the sixth connection point 16 to a tenth connection point 20 arranged on the main loop A between the second connection point 12 and the fourth connection point 14. The fifth bypass branch F successively comprises a seventh expansion valve 37 and a fourth heat exchanger 4 configured to exchange heat with an interior air flow Fi.

[0104] The fourth exchanger 4 is arranged in the heating, ventilation and / or air conditioning system 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. The fourth exchanger 4 allows the interior air flow and thus the passenger compartment of the vehicle to be cooled.

[0105] In this second embodiment in which the fifth bypass branch F is present, the internal exchanger 6 is configured to allow a heat exchange between the refrigerant circulating between the ninth connection point 19 and the sixth connection point 16 and the refrigerant circulating downstream of the accumulation device 8 and upstream of an inlet 7a of the compressor 7.

[0106] The second branch C comprises a sixth regulator 36 arranged between the fourth connection point 14 and the fifth connection point 15.

[0107] 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.

[0108] The main loop A comprises a first shut-off valve 41 arranged between the first connection point 11 and the seventh connection point 17.

[0109] In the first embodiment corresponding to FIG. 1, the main loop A comprises a second stop valve 42 arranged between the second connection point 12 and the fourth connection point 14. In the second embodiment corresponding to Figure 2, the main loop A comprises a second stop valve 42 arranged between the second connection point 12 and the tenth connection point 20.

[0110] The first shut-off valve 41 is an electrically controlled valve. Similarly, the second shut-off valve 42 is an electrically controlled valve. Each shut-off valve is, for example, controlled by the electronic control unit 62.

[0111] 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 through the first one-way valve 43 of 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 through the first one-way valve 43 of the third connection point 13 to the first exchanger 1.

[0112] The refrigerant circuit 10 comprises a second one-way valve 44 arranged on the third bypass branch D. The second one-way valve 44 is configured to allow circulation of refrigerant fluid through the second one-way valve 44 from the fifth connection point 15 to the sixth connection point 16 and configured to prohibit circulation of refrigerant fluid through the second one-way valve 44 from the sixth connection point 16 to the fifth connection point 15.

[0113] The refrigerant circuit 10 comprises a third one-way valve 45 arranged on the main loop A between the fourth exchanger 4 and the tenth connection point 20. The third one-way valve 45 is configured to allow circulation of refrigerant fluid through the third one-way valve 45 of the fourth exchanger 4 to the tenth connection point 20. The third one-way valve 45 is also configured to prohibit circulation of refrigerant fluid through the third one-way valve 45 from the tenth connection point 20 to the fourth exchanger 4.

[0114] The first one-way valve 43 is for example a non-return valve. Likewise, the second one-way valve 44 and the third one-way valve 45 may also be a check valve. A check valve is a passive device that reacts to the pressure difference between its inlet and outlet. No electrical control is required for its operation. Alternatively, each one-way valve 43, 44, 45 may be an electrically operated valve.

[0115] According to an exemplary embodiment, the element 25 of the electric powertrain of the vehicle comprises an electrical energy storage battery. According to a variant, or in a complementary manner, the element 25 of the electric traction chain of the vehicle comprises an electric traction motor of the vehicle. According to another variant or in a complementary manner, the element 25 of the electric traction chain of the vehicle comprises an electronic unit for controlling the electric traction motor of the vehicle.

[0116] 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 fluid circulating in a heat transfer fluid circuit 40. A circulation pump, not shown, allows the heat transfer fluid to circulate in circuit 40. According to the schematic example, circuit 30 and circuit 40 are independent, that is to say they are not connected.

[0117] 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 powertrain of the vehicle. The heat transfer fluid thus allows a heat transfer between the refrigerant fluid and the element 25 of the electric powertrain. 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 circuit 40 is, for example, a mixture of water and glycol.

[0118] Each regulator 31, ..., 37 is for example an electronic regulator.

[0119] 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.

[0120] 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 comprising: a main loop A comprising successively, according to the direction of circulation 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 a heat exchange between the refrigerant fluid circulating between the first expansion valve 31 and the second expansion valve 32 and the refrigerant fluid circulating downstream of the accumulation device 8 and upstream of an inlet 7a of the compressor 7, 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 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 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 second branch branch C downstream of the third exchanger 3 and upstream of the fourth connection point 14 to a sixth connection point 16 arranged on the main loop A between the first expansion valve 31 and the second expansion valve 32,a fourth branch branch E connecting a seventh connection point 17 arranged on the main loop A downstream of the first connection point 11 and upstream of the first exchanger 1 to an eighth connection point 18 arranged on the second branch branch C downstream of the fourth regulator 34 and upstream of the, third exchanger 3, the fourth branch of derivation E comprising a fifth regulator 35. The proposed method includes the following steps: (i) provide a first flow Q1 of high-pressure refrigerant fluid at the outlet of the compressor 7, (ii) dividing the first flow Q1 of high-pressure refrigerant into a second flow Q2 circulating in the main loop A and a third flow Q3 circulating in the first bypass branch B, (iii) circulating at least a portion of the second flow Q2 of high-pressure refrigerant fluid in the first heat exchanger 1, (iv) expanding at least a portion of the high pressure refrigerant from the first heat exchanger 1 to a low pressure, (v) circulating the refrigerant at low pressure in the second exchanger 2, (vi) expanding the third flow Q3 to low pressure so that the third flow Q3 joins the refrigerant coming from the second exchanger 2 so as to form the first flow Q1, the first flow Q1 of low pressure refrigerant joining the compressor 7.

[0121] In the proposed method, the thermal energy taken from the outside air flow Fe at the second exchanger 2 contributes to heating the passenger compartment of the vehicle at the first exchanger 1. The flow of refrigerant circulating in the first branch B provides the thermal energy making it possible to complete the thermodynamic cycle while limiting the quantity of heat extracted from the outside air flow Fe. The risks of icing of the second exchanger 2 are thus reduced, without limiting the thermal power supplied to the passenger compartment.

[0122] The steps described account for the proposed method by taking the compressor 7 as the starting point for the circulation of refrigerant fluid. The different steps do not necessarily occur in the order described. In particular, in the case where a flow of refrigerant fluid is divided into two flows at a connection point, these two flows continue their circulation simultaneously and no order can be defined.

[0123] According to the proposed method, the first exchanger 1 operates as a refrigerant fluid cooler. The first exchanger 1 thus makes it possible to heat the interior air flow Fi, either directly or indirectly.

[0124] According to the proposed method, the second exchanger 2 operates as a refrigerant fluid evaporator. The second exchanger 2 thus makes it possible to absorb thermal power from the outside air flow Fe.

[0125] According to the proposed method, the third exchanger 3 can operate as a refrigerant fluid cooler. The third heat exchanger 3 makes it possible to 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. According to operating modes not shown, the third exchanger 3 can operate as a refrigerant fluid evaporator.

[0126] Figures 3 to 5 illustrate 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 Figure 2. The portions of the circuit 10 in which a flow of refrigerant fluid circulates are in continuous thick lines, while the portions in which the refrigerant fluid does not circulate are in thin dotted lines. The different arrows indicate the direction of circulation of the refrigerant fluid in the different portions of the refrigerant circuit 10.

[0127] Figure 3 shows the operation of the thermal conditioning system according to a first example of implementation of the process. According to this first example, the refrigerant fluid coming from the first exchanger 1 circulates in the first expansion valve 31 where it passes at intermediate pressure, in the internal exchanger 6, then in the second expansion valve 32 where it passes at low pressure.

[0128] According to this first example of implementation, the flow rate of refrigerant circulating in the second exchanger 2 is equal to the flow rate of refrigerant circulating in the first exchanger 1. It is understood that the two flow rates are equal during steady-state operation, i.e. when thermal equilibrium is reached.

[0129] The value of the so-called “high pressure” pressure, at the outlet of compressor 7, is for example between 40 bars and 130 bars. The value of the so-called "intermediate" pressure, after expansion for example by the first regulator 31, is lower than the value of the high pressure. The intermediate pressure is for example between 20 bars and 70 bars. The value of the so-called “low pressure”, after expansion for example in the second regulator 32, is lower than the value of the intermediate pressure. Low pressure is for example between 10 bars and 40 bars.

[0130] According to this first example of implementation of the process: - The first regulator 31 is in the partially open position. - The second regulator 32 is in the partially open position. - The third regulator 33 is in the partially open position. - The fourth regulator 34 is in the closed position. - The fifth regulator 35 is in the closed position. - The sixth regulator 36 is in the closed position.

[0131] According to this first example of implementation, the refrigerant fluid circulating in the main loop A downstream of the first connection point 11 successively passes through the first exchanger 1, the first expansion valve 31, the first heat exchange section 6a of the internal exchanger 6, the second expansion valve 32, the second exchanger 2, and reaches the second connection point 12. The refrigerant fluid circulating in the first branch B circulates in the third expansion valve 33 and joins the refrigerant fluid coming from the second exchanger 2 at the second connection point 12. These two refrigerant fluid flows are thus combined into a single flow. This single flow circulates in the main loop A up to the fourth connection point 14, then in the accumulation device 8, in the second heat exchange section 6b of the internal exchanger 6, and reaches the inlet 7a of the compressor 7. The first stop valve 41 and the second stop valve 42 are both in the open position.

[0132] Figure 4 shows the operation of the thermal conditioning system according to a second example of implementation of the process. According to this second example of implementation of the method, the second flow Q2 of high-pressure refrigerant fluid circulates in the first exchanger 1 and is divided into a first part Q2A circulating in the main loop A and a second part Q2C circulating in the second bypass branch C. The refrigerant Q2C circulating in the second branch of bypass C circulates in the fourth expansion valve 34 where it passes at low pressure, and the low pressure refrigerant coming from the third exchanger 3 joins the fluid low pressure refrigerant from the second exchanger 2 and the first bypass branch B.

[0133] In this second example of implementation, the low-pressure refrigerant circulating in the third exchanger 3 recovers the heat dissipated by the thermal losses of the element 25 of the electric powertrain of the vehicle. The energy efficiency is thus improved.

[0134] The refrigerant circulating in the main loop A from the third connection point 13 to the sixth connection point 16 circulates in the first expansion valve 31 and passes at intermediate pressure.

[0135] According to this second example of implementation of the process: - The first regulator 31 is in the partially open position. - The second regulator 32 is in the partially open position. - The third regulator 33 is in the partially open position. - The fourth regulator 34 is in the partially open position. - The fifth regulator 35 is in the closed position. - The sixth regulator 36 is in the fully open position.

[0136] In steady state, the flow rate of refrigerant fluid Q2A circulating in the second exchanger 2 is less than the flow rate of refrigerant fluid Q2 circulating in the first exchanger 1. In fact, part of the refrigerant fluid coming from the first exchanger 1 then circulates in the third exchanger 3 and reaches the compressor 7 without passing through the second exchanger 2.

[0137] According to this second example of implementation, the circulation of the refrigerant fluid in the main loop A between the first connection point 11 and the third connection point 13 is identical to the first example. Similarly, the circulation in the first branch of derivation B is identical to the first example. At the third connection point, the flow Q2 of refrigerant fluid coming from the first exchanger 1 is divided into a first part Q2A which circulates in the main loop A towards the first expansion valve 31 and a second part Q2C which circulates in the second bypass branch C towards the fourth expansion valve 34. The first part Q2A circulates successively in the first expander 31, the first heat exchange section 6a of the internal exchanger 6, the second expander 32, the second exchanger 2, and joins at the second connection point 12 the refrigerant fluid coming from the first branch B. As in the first example, these two refrigerant fluid flows combine into a single flow which circulates in the main loop A up to the fourth connection point 14. The second part Q2C circulates in the fourth expander 34 and passes at low pressure, then in the third exchanger 3, then in the sixth expander 36, and joins at the level of the fourth connection point 14 the refrigerant fluid circulating in the main loop A. The flow of refrigerant fluid resulting from the combination of the two flow rates at point 14 circulates successively in the accumulation device 8, in the second heat exchange section 6b of the internal exchanger 6, and reaches the inlet 7a of the compressor 7.

[0138] The first stop valve 41 and the second stop valve 42 are both in the open position. The second one-way valve 44 prevents the intermediate pressure refrigerant at the sixth connection point 16 from flowing into the third bypass branch D to the fifth connection point 15.

[0139] Figure 5 shows the operation of the thermal conditioning system according to a third example of implementation of the process. According to this third example of implementation of the method, the second flow Q2 of high-pressure refrigerant circulating in the main loop A is divided into a first part Q2-1 circulating in the first exchanger 1 then in the second bypass branch C, and a second part Q2-2 complementary to the first part Q2-1 circulating in the fourth bypass branch E, the first part Q2-1 and the second part Q2-2 joining upstream of the third exchanger 3 and forming the second flow Q2. The second flow Q2 circulates successively in the third exchanger 3, in the second bypass branch C, in the third bypass branch D, in the second expansion valve 32, in the second exchanger 2. The second flow Q2 joins the third flow Q3 and forms the first flow Q1, the first flow Q1 joining the compressor 7.

[0140] The high-pressure refrigerant circulating in the main loop A heats the interior air flow Fi and thus the vehicle's passenger compartment. The refrigerant circulating in the fourth branch E joins the refrigerant coming from the first exchanger 1, and the resulting mixture allows, by releasing heat in the third exchanger 3, to heat the element 25 of the vehicle's powertrain.

[0141] According to this third example of implementation of the process: - the refrigerant fluid coming from the first exchanger 1 is expanded by the fourth expander 34 to an intermediate pressure lower than the high pressure, - the refrigerant fluid circulating in the fourth branch E is expanded by the fifth expansion valve 35 to the intermediate pressure, and - the refrigerant fluid circulating in the third bypass branch D is expanded by the second expander 32 to a low pressure lower than the intermediate pressure.

[0142] According to this third example of implementation of the process: - The first regulator 31 is in the closed position. - The second regulator 32 is in the partially open position. - The third regulator 33 is in the partially open position. - The fourth regulator 34 is in the partially open position. - The fifth regulator 35 is in the partially open position. - The sixth regulator 36 is in the closed position.

[0143] In steady state, the flow rate of refrigerant circulating in the second exchanger 2 is greater than the flow rate of refrigerant circulating in the first exchanger 1. The flow rate of refrigerant circulating in the second exchanger 2 is equal to the flow rate of refrigerant circulating in the third exchanger 3, this flow rate being designated by Q2. In fact, the refrigerant fluid coming from the first exchanger 1 is joined by the refrigerant fluid circulating in the fourth bypass branch E, and the assembly then joins the second exchanger 2 by passing successively through the third exchanger 3, through the third bypass branch D and through the second expansion valve 32.

[0144] According to this third example of implementation, the circulation of the refrigerant fluid in the main loop A between the first connection point 11 and the seventh connection point 17 is identical to the first and second examples. Similarly, the circulation in the first branch of bypass B is identical to the first and second examples. At the seventh connection point 17, the flow Q2 of refrigerant fluid is divided into a first part Q2-1 which circulates in the main loop A towards the first exchanger 1 and a second part Q2-2 which circulates in the fourth bypass branch E towards the fifth expansion valve 35. The first part Q2-1 circulates in the first exchanger 1, is redirected at the third connection point 13 towards the second branch branch C and passes through the fourth regulator 34. At the eighth connection point 18, the refrigerant from the fourth expansion valve 34 and the refrigerant from the fifth expansion valve 35 join. The resulting flow Q2 passes through the third exchanger 3, then is redirected at the fifth exchanger 5 to the third bypass branch D, and joins the main loop A at the sixth connection point 16. The sixth connection point 16 is downstream of the first heat exchange section 6a, which is therefore not traversed by refrigerant fluid. The flow Q2 of refrigerant fluid coming from the third bypass branch D circulates successively in the second expansion valve 32 then in the second exchanger 2, and joins, as for the two other examples of implementation of the method, the flow Q3 of refrigerant fluid coming from the third expansion valve 33. As before, the resulting flow Q1 circulates in the main loop A up to the fourth connection point 14, then in the accumulator 8, in the second heat exchange section 6b of the internal exchanger 6, and returns to the inlet 7a of the compressor 7.

[0145] According to a particular case of the third example of implementation of the process: - a flow rate of refrigerant fluid circulating in the fourth branch of bypass E is less than a first predefined threshold, - an indoor airflow rate Fi is lower than a second predefined threshold.

[0146] The flow rate of refrigerant circulating in the fourth branch of bypass E can be zero. The flow rate of the interior air flow Fi can be zero. For this, the first motor-fan unit can be kept stopped. Alternatively or in addition, a movable flap, not shown, can be arranged in a position blocking the passage of air.

[0147] When the indoor air flow rate Fi is lower than the first predefined threshold, the heat exchange in the first exchanger 1 is negligible. When the flow rate of the interior air flow Fi is zero, there is no heat exchange at the level of the first exchanger 1. When the flow rate of refrigerant circulating in the fourth branch of bypass E is also zero, the first exchanger 1 and the third exchanger 3 are connected in series without supply of refrigerant between the outlet 1 b of the first exchanger 1 and the inlet 3a of the third interchange 3. All the energy of the refrigerant fluid reaching the first exchanger 1 makes it possible to heat the element 25 of the traction chain at the level of the third exchanger 3. When the flow rate of refrigerant circulating in the fourth bypass branch E is lower than the second predefined threshold, the input of thermal energy by the fourth bypass branch E is negligible. The heat exchange in the third exchanger 3 is carried out by the refrigerant coming from the first exchanger 1.

[0148] The principle of the control allowing the operation of the different actuators of the thermal conditioning system 100 to be controlled will now be described.

[0149] A control of the expansion carried out by the first expansion valve 31 makes it possible to limit the discharge temperature of the compressor 7.

[0150] The proposed control process thus comprises the following steps: - determine a maximum admissible temperature Tmax of the refrigerant fluid at the outlet of the compressor 7, - determine a temperature T7 of the refrigerant fluid at the outlet of compressor 7, - control an expansion of the refrigerant fluid in the first expansion valve 31 so that the determined temperature T7 is lower than the maximum temperature Tmax.

[0151] When the first heat exchange section 6a of the internal exchanger 6 is traversed by refrigerant fluid, the control of the value of the pressure of the refrigerant fluid in the first heat exchange section 6a makes it possible to control the efficiency of the internal exchanger 6, that is to say the quantity of heat exchanged between the first heat exchange section 6a and the second heat exchange section 6b. It is thus possible to adjust the temperature at the inlet 7a of the compressor 7, and therefore also the discharge temperature at the outlet 7b of the compressor 7. The discharge temperature T7 of the compressor 7 can thus be maintained at a value less than or equal to a maximum admissible temperature.

[0152] The control process can thus include the following sub-steps: - reduce a passage section of the refrigerant fluid through the first expansion valve 31 if the determined temperature T7 of the refrigerant fluid at the outlet of the compressor 7 is higher than a first target value, - increase a passage section of the refrigerant fluid through the first expansion valve 31 if the determined temperature T7 of the refrigerant fluid at the outlet of the compressor 7 is lower than the first target value.

[0153] A control of the expansion carried out by the second expansion valve 32 makes it possible to control the discharge pressure of the compressor 7, and thus the value of the high pressure of the thermodynamic cycle.

[0154] The proposed control process thus comprises the following steps: - determine a pressure P7 of the refrigerant fluid at the outlet of compressor 7, - increase a passage section of the refrigerant fluid through the second expansion valve 32 if the determined pressure P7 of the refrigerant fluid at the outlet of the compressor 7 is greater than a second target value, - reduce a passage section of the refrigerant fluid through the second expansion valve 32 if the determined pressure P7 of the refrigerant fluid at the outlet of the compressor 7 is lower than the second target value.

[0155] Joint control of the flow rate circulating in the refrigerant circuit 10 and the expansion carried out by the third expansion valve 33 makes it possible to control the heating power supplied by the first exchanger 1 while limiting the thermal power absorbed from the outside air flow Fe at the level of the second exchanger 2.

[0156] The first exchanger 1 provides a thermal power P1. The control process can thus include the following sub-steps: - controlling the flow rate Q1 of refrigerant fluid discharged by the compressor 7 and controlling a passage section of the refrigerant fluid through the third expansion valve 33 so as to control the pressure of the refrigerant fluid in the second exchanger 2 at a value greater than a predefined minimum threshold and so as to control at a third target value the thermal power P1 supplied by the first exchanger 1.

[0157] The level of expansion applied by the third expansion valve 33 makes it possible, in combination with the flow rate supplied by the compressor 7, to control the value of the low pressure of the thermodynamic cycle as well as the heating power supplied by the first exchanger 1, i.e. that supplied by the first exchanger 1. By controlling the low pressure to a sufficiently high value, the thermal power absorbed by the second exchanger 2 is limited, which avoids icing the second exchanger 2 in a cold environment.

[0158] The value of the predefined minimum pressure threshold may depend on the ambient temperature. The process can thus include the following sub-steps: - determine the temperature of the outside air flow Fe, - determine the value of the predefined minimum pressure threshold as a function of the determined temperature of the outside air flow.

[0159] The control process includes the step: - control a rotation speed of the compressor 7 in order to control the flow of refrigerant fluid in the refrigerant circuit 10.

[0160] The total flow rate circulating in the refrigerant circuit 10 is the flow rate delivered by the compressor 7.

[0161] The control process includes the following steps: - increase the rotation speed of the compressor 7 so as to increase the total flow rate circulating in the refrigerant circuit 10, and - reduce the rotation speed of the compressor 7 so as to reduce the total flow rate circulating in the refrigerant circuit 10.

[0162] A control of the expansion carried out by the fourth expansion valve 34 makes it possible to control the value of the superheating of the refrigerant fluid at the outlet of the third exchanger 3.

[0163] The control process may include the following sub-steps: - determine an overheating Sh3 of the refrigerant fluid at the outlet of the third exchanger 3, - controlling a passage section of the refrigerant fluid through the fourth expansion valve 34 so as to adjust the superheat Sh3 of the refrigerant fluid at the outlet of the third exchanger 3 to a fourth target value.

[0164] The control process may include the following sub-steps: - increase a passage section of the refrigerant fluid through the fourth expansion valve 34 if the determined superheat Sh3 of the refrigerant fluid at the outlet of the third exchanger 3 is greater than the fourth target value, - reduce a passage section of the refrigerant fluid through the fourth expansion valve 34 if the determined superheat Sh3 of the refrigerant fluid at the outlet of the third exchanger 3 is lower than the fourth target value.

[0165] The superheating of the refrigerant fluid is defined by the difference between the temperature of the refrigerant fluid and the saturation temperature of the refrigerant fluid, this saturation temperature being that corresponding to the pressure of the refrigerant fluid.

[0166] A control of the expansion carried out by the fifth expansion valve 35 makes it possible to control the heating power supplied by the third exchanger 3.

[0167] The control process may include the steps: - determine a thermal power P3 supplied by the third exchanger 3 to element 25 of the traction chain, - controlling a passage section of the refrigerant fluid through the fifth expansion valve 35 so as to adjust the thermal power P3 supplied by the third exchanger 3 to a fifth target value.

[0168] The thermal power supplied by the third exchanger 3 to the element 25 of the traction chain is for example determined from the value of the flow rate of heat transfer liquid in the circuit 40, and from the value of the temperature difference of the heat transfer liquid between the inlet and the outlet of the third exchanger 3. The heat capacity of the heat transfer fluid is also taken into account in the calculation of the thermal power supplied by the third exchanger 3.

[0169] The control process may include the following sub-steps: - increase a passage section of the refrigerant fluid through the fifth expansion valve 35 if the thermal power supplied by the third exchanger 3 is less than the fifth target value, - reduce a passage section of the refrigerant fluid through the fifth expansion valve 35 if the thermal power supplied by the third exchanger 3 is less than the fifth target value.

[0170] When the thermal coupling between the first exchanger 1 and the interior air flow Fi is a direct coupling, a control of the expansion carried out by the fourth expansion valve 34 makes it possible to control the temperature of the interior air flow Fi after exchange with the first exchanger 1.

[0171] The control process may include the steps: - receive a temperature setpoint Tel of the interior air flow Fi at the outlet of the first exchanger 1, - determine a temperature T 1 of the interior air flow Fi at the outlet of the first exchanger 1, - control a passage section of the refrigerant fluid in the fourth expansion valve 34 so that the determined temperature T1 of the interior air flow Fi at the outlet of the first exchanger 1 is equal to the temperature setpoint Tel.

[0172] The control process may include the following sub-steps: - increase a passage section of the refrigerant fluid through the fourth expansion valve 34 if the determined temperature T 1 of the interior air flow Fi at the outlet of the first exchanger I is lower than the temperature setpoint Tel, and - reduce a passage section of the refrigerant fluid through the fourth expansion valve 34 if the determined temperature T1 of the interior air flow Fi at the outlet of the first exchanger 1 is higher than the temperature setpoint Tel.

[0173] When the air flow Fi through the first exchanger 1 is low or even zero, the heat exchange carried out by the first exchanger 1 is negligible or zero. A circulation of refrigerant fluid through the first exchanger 1 is however maintained, in order to ensure a return of the oil contained in the refrigerant fluid to the compressor 7, and thus avoid an accumulation of this oil in the first exchanger 1.

[0174] When the thermal coupling between the first exchanger 1 and the indoor air flow Fi is an indirect coupling, the principle is the same and the temperature T 1 of the indoor air flow Fi at the outlet of the first exchanger 1 is replaced by a temperature T1A of the indoor air flow Fi at the outlet of the exchanger 1 A of the heat transfer liquid circuit 40. The same applies to the temperature setpoint Tel of the interior air flow Fi at the outlet of the first exchanger 1 which is replaced by a temperature setpoint Tel A of the interior air flow Fi at the outlet of the exchanger 1 A of the heat transfer liquid circuit 40.

[0175] According to this particular operation of the third example of implementation of the process: - the first regulator 31 and the sixth regulator 36 are in the closed position, - the second regulator 32, the third regulator 33, the fourth regulator 34, and the fifth regulator 35 are in the partially open position.

[0176] The fifth expansion valve 35 may optionally be in the closed position. In this case, the first exchanger 1 and the third exchanger 3 are connected in series, and the refrigerant fluid can successively heat the interior air flow Fi then the heat transfer fluid of the heat transfer fluid circuit 40.

[0177] Thus, the refrigerant fluid coming from the first exchanger 1 is redirected at the third connection point 13 towards the fourth expansion valve 34 and the third exchanger 3. The refrigerant fluid circulating in the fourth branch E joins the refrigerant fluid coming from the fourth expansion valve 34 at the eighth connection point 18. The resulting flow is directed at the fifth connection point 15 to the third branch of derivation D and joins the main loop A at the sixth connection point 16.

[0178] According to the illustrated examples of implementation of the process, the fourth exchanger 4 does not participate in heat exchanges. The seventh expansion valve 37 is in the closed position, and the fifth branch of bypass F is not crossed by a flow of refrigerant fluid.

Claims

Claims

1. Method for controlling a thermal conditioning system for a motor vehicle, the thermal conditioning system (100) comprising a 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 external 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 fluid circulating between the first expansion valve (31) and the second expansion valve (32) and the refrigerant fluid circulating downstream of the accumulation device (8) and upstream of an inlet (7a) of the compressor (7), 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 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 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 second branch branch (C) downstream of the third exchanger (3) and upstream of the fourth connection point (14) to a sixth connection point connection (16) arranged on the main loop (A) between the first regulator (31) and the second regulator (32), A fourth branch branch (E) connecting a seventh connection point (17) arranged on the main loop (A) downstream of the first connection point (11) and upstream of the first exchanger (1) to an eighth connection point (18) arranged on the second branch branch (C) downstream of the fourth regulator (34) and upstream of the third exchanger (3), the fourth branch branch (E) comprising a fifth regulator (35), the method comprising the steps: (i) providing a first flow (Q1) of high-pressure refrigerant fluid at the outlet of the compressor (7), (ii) dividing the first flow (Q1) of high-pressure refrigerant into a second flow (Q2) circulating in the main loop (A) and a third flow (Q3) circulating in the first bypass branch (B), (iii) circulating at least part of the second flow (Q2) of high-pressure refrigerant fluid in the first heat exchanger (1), (iv) expanding at least a portion of the high pressure refrigerant fluid from the first heat exchanger (1) to a low pressure, (v) circulating the refrigerant at low pressure in the second exchanger (2), (vi) expanding the third flow (Q3) to low pressure so that the third flow (Q3) joins the refrigerant coming from the second exchanger (2) so as to form the first flow (Q1), the first flow (Q1) of low pressure refrigerant joining the compressor (7).

2. Method according to claim 1, in which the refrigerant coming from the first exchanger (1) circulates in the first expansion valve (31) where it passes at intermediate pressure, in the internal exchanger (6), then in the second expansion valve (32) where it passes at low pressure, and in which the flow rate of refrigerant circulating in the second exchanger (2) is equal to the flow rate of refrigerant circulating in the first exchanger (1).

3. Method according to claim 1, in which the second flow (Q2) of high-pressure refrigerant fluid circulates in the first exchanger (1) and is divided into a first part (Q2A) circulating in the main loop (A) and a second part (Q2C) circulating in the second bypass branch (C), in which the refrigerant fluid (Q2C) circulating in the second bypass branch (C) circulates in the fourth expansion valve (34) where it passes at low pressure, and in which the low pressure refrigerant fluid coming from the third exchanger (3) joins the low pressure refrigerant fluid coming from the second exchanger (2) and the first bypass branch (B).

4. Method according to claim 1, in which the second flow (Q2) of high-pressure refrigerant circulating in the main loop (A) is divided into a first part (Q2-1) circulating in the first exchanger (1) then in the second bypass branch (C), and a second part (Q2-2) complementary to the first part (Q2-1) circulating in the fourth bypass branch (E), the first part (Q2-1) and the second part (Q2-2) joining upstream of the third exchanger (3) and forming the second flow (Q2), the second flow (Q2) circulating successively in the third exchanger (3), in the second bypass branch (C), in the third bypass branch (D), in the second expansion valve (32), in the second exchanger (2), the second flow (Q2) joining the third flow (Q3) and forming the first flow (Q1), the first flow (Q1) joining the compressor (7).

5. A method according to claim 4, wherein: - the refrigerant fluid coming from the first exchanger (1) is expanded by the fourth expander (34) to an intermediate pressure lower than the high pressure, - the refrigerant fluid circulating in the fourth bypass branch (E) is expanded by the fifth expansion valve (35) to the intermediate pressure, and - the refrigerant fluid circulating in the third bypass branch (D) is expanded by the second expansion valve (32) to a low pressure lower than the intermediate pressure.

6. A method according to claim 4, wherein: - a flow rate of refrigerant circulating in the fourth bypass branch (E) is lower than a first predefined threshold, - an indoor airflow rate (Fi) is lower than a second predefined threshold.

7. Control method according to one of the preceding claims, comprising the steps: - determine a maximum admissible temperature (Tmax) of the refrigerant fluid at the outlet of the compressor (7), - determine a temperature (T7) 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 (T7) is lower than the maximum temperature (Tmax).

8. Control method according to one of the preceding claims, comprising the steps: - determine a pressure (P7) of the refrigerant fluid at the outlet of the compressor (7), - increasing a passage section of the refrigerant fluid through the second expansion valve (32) if the determined pressure (P7) of the refrigerant fluid at the outlet of the compressor (7) is greater than a second target value, - reduce a passage section of the refrigerant fluid through the second expansion valve (32) if the determined pressure (P7) of the refrigerant fluid at the outlet of the compressor (7) is lower than the second target value.

9. Control method according to one of claims 1 to 3, in which the first exchanger (1) provides a thermal power (P1), the method comprising the sub-steps: - controlling a flow rate (Q1) of refrigerant fluid delivered by the compressor (7) and controlling a passage section of the refrigerant fluid through the third expansion valve (33) so as to control the pressure of the refrigerant fluid in the second exchanger (2) at a predefined minimum threshold and so as to control at a third target value the thermal power (P1) supplied by the first exchanger (1).

10. 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).

11. Control method according to claim 3, comprising the sub-steps: - determine an overheating (Sh3) of the refrigerant fluid at the outlet of the third exchanger (3), - controlling a passage section of the refrigerant fluid through the fourth expansion valve (34) so as to adjust the superheat (Sh3) of the refrigerant fluid at the outlet of the third exchanger (3) to a fourth target value.

12. A control method according to claim 4, comprising the steps: - determine a thermal power (P3) supplied by the third exchanger (3) to the element (25) of the traction chain, - check a section of passage of the refrigerant fluid through the fifth expansion valve (35) so as to adjust the thermal power (P3) supplied by the third exchanger (3) to a fifth target value.

13. A control method according to claim 4 or 12, comprising the steps: - receive a temperature setpoint (Tel) of the interior air flow (Fi) at the outlet of the first exchanger (1), - determine a temperature (T1) of the interior air flow (Fi) at the outlet of the first exchanger (1), - control a passage section of the refrigerant fluid in the fourth expansion valve (34) so that the determined temperature (T 1 ) of the interior air flow (Fi) at the outlet of the first exchanger (1 ) is equal to the temperature setpoint (Tel ).

14. Thermal conditioning system (100) 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 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 external 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 fluid circulating between the first expansion valve (31) and the second expansion valve (32) and the refrigerant fluid circulating downstream of the accumulation device (8) and upstream of an inlet (7a) of the compressor (7), 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 point of connection (13) arranged on the main loop (A) between the first exchanger (1) and the first pressure reducer (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 pressure reducer (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 second branch branch (C) downstream of the third exchanger (3) and upstream of the fourth connection point (14) to a sixth connection point (16) arranged on the main loop (A) between the first regulator (31) and the second regulator (32), A fourth branch branch (E) connecting a seventh connection point (17) arranged on the main loop (A) downstream of the first connection point (11) and upstream of the first exchanger (1) to an eighth connection point (18) arranged on the second branch branch (C) downstream of the fourth regulator (34) and upstream of the third exchanger (3), the fourth branch branch (E) comprising a fifth regulator (35), - A fifth branch branch (F) connecting a ninth connection point (19) arranged on the main loop (A) between the first expansion valve (31) and the sixth connection point (16) to a tenth connection point (20) arranged on the main loop (A) between the second connection point (12) and the fourth connection point (14), the fifth branch branch (F) successively comprising a seventh expansion valve (37) and a fourth heat exchanger (4) configured to exchange heat with an interior air flow (Fi), - an electronic control unit (62) configured to implement the method according to one of the preceding claims.

15. Computer program stored in a memory and configured to implement the method according to any one of claims 1 to 13.

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