Method for controlling a thermal conditioning system for a motor vehicle

Abstract

The invention relates to a method for controlling a thermal conditioning system (100) for a motor vehicle, the thermal conditioning system (100) comprising a refrigerant fluid circuit (10) having a main loop (A) comprising a compressor (7), a first heat exchanger (1), a first and a second expansion device (31, 32), a second heat exchanger (2), and a bypass branch (E), wherein the method comprises the steps of: supplying a high-pressure refrigerant flow (D), circulating a first portion (P1) of the high-pressure refrigerant through the first heat exchanger (1), and a second portion (P2) through the bypass branch (E), expanding the refrigerant flowing through the bypass branch (E) to an intermediate pressure, and expanding the refrigerant from the first heat exchanger (1) to the intermediate pressure, circulating the intermediate-pressure refrigerant through a third heat exchanger (3), and expanding same to a low pressure.

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 interior and cooling it, as well as heating and cooling the battery cells storing electrical energy. [3] Heating methods are frequently carried out by a so-called heat pump cycle in which the heat from the high-pressure refrigerant is transferred to one or more components to be heated, and in which the heat required for vaporizing the low-pressure refrigerant is taken from an outside air flow. [4] When the ambient temperature decreases, and in particular when this ambient temperature is negative, the thermal power that can be extracted from the outside air flow decreases, which also limits the power available for heating. In addition, the heat exchanger in which the evaporation of the refrigerant takes place is likely to ice up, which further limits the heating thermal power. It is thus difficult to obtain sufficient heating power to heat the passenger compartment or the battery cells. [5] It is therefore desirable to be able to heat the vehicle interior using another method, and to be able to adjust the heating parameters on demand. Summary [6] 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 successively comprising, according to 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, a first branch branch connecting a first connection point arranged on the main loop downstream of an outlet of the compressor and upstream of the first exchanger to a second connection point arranged on the main loop downstream of the second heat exchanger and upstream of the accumulation device, the first branch branch comprising a third expansion valve, a second branch branch connecting a third connection point arranged on the main loop between the first exchanger and the 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 branch successively comprising a fourth expansion valve, a third heat exchanger thermally coupled with an element of an electric powertrain of a motor vehicle, and a fifth expansion valve,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 regulator and the second regulator, a fourth branch connecting a seventh connection point, arranged on the main loop downstream of the first connection point and upstream of the first exchanger at an eighth connection point arranged on the second branch downstream of the fourth regulator and upstream of the third exchanger, the fourth branch comprising a sixth regulator, the method comprising the steps: (i) provide a high pressure refrigerant flow at the compressor outlet and circulate the refrigerant flow in the main loop, (ii) dividing the high-pressure refrigerant flow into a first part circulating successively in the first exchanger and the fourth expansion valve, and a second part circulating in the fourth bypass branch towards the sixth expansion valve, the refrigerant coming from the fourth expansion valve joining the refrigerant coming from the sixth expansion valve so as to form a refrigerant flow, (iii) circulating the flow of refrigerant fluid formed successively in the third heat exchanger and in the fifth expansion valve, the refrigerant fluid coming from the fifth expansion valve joining the compressor. [7] The high-pressure refrigerant circulating in the first exchanger can heat the interior air flow and thus the passenger compartment of the vehicle. The thermal energy remaining in the refrigerant after heating the interior air flow is generally insufficient to ensure sufficient heating of the element of the powertrain. The flow of refrigerant circulating in the fourth branch branch makes it possible to increase the energy supplied to the element, and thus to increase the heating power. According to the operating mode corresponding to the proposed method, the second exchanger is not thermally active and does not evaporate refrigerant. The passenger compartment and the element of the powertrain can be heated without risking icing the second exchanger. This operating mode is therefore particularly advantageous at ambient temperatures below 0°C. [8] The features listed in the following paragraphs may be implemented independently of each other or in any technically possible combination: [9] In steady state, the different stages of the proposed process are: (i) providing a first flow of high-pressure refrigerant fluid at the compressor outlet and circulating the first flow of refrigerant fluid in the main loop, (ii) dividing the first flow of high-pressure refrigerant into a second flow circulating successively in the first exchanger and the fourth expansion valve, and a third flow circulating in the fourth bypass branch towards the sixth expansion valve, the refrigerant fluid from the fourth expansion valve joining the refrigerant fluid from the sixth expansion valve so as to form the first flow of refrigerant fluid, (iii) circulating the first flow of refrigerant fluid successively in the third heat exchanger and in the fifth expansion valve, the first flow of refrigerant fluid from the fifth expansion valve joining the compressor.

[0010] According to a first example of implementation of the control process: - in step (ii), the fourth expander expands the refrigerant coming from the first exchanger to an intermediate pressure lower than the high pressure, and the sixth expander expands the refrigerant circulating in the fourth bypass branch to the intermediate pressure, and - in step (iii), the fifth expander expands the intermediate pressure refrigerant fluid from the third heat exchanger to a low pressure lower than the intermediate pressure.

[0011] According to this first example of implementation of the method, the high-pressure refrigerant circulating in the first exchanger heats the interior air flow and thus the passenger compartment of the vehicle. The enthalpy of the refrigerant leaving the first exchanger is lower than the enthalpy of the refrigerant entering the compressor. The thermodynamic cycle carried out by the refrigerant passing through the first exchanger is therefore not completed. In order to complete the thermodynamic cycle, the intermediate-pressure refrigerant coming from the fourth branch increases the enthalpy of the refrigerant entering the third exchanger. The thermodynamic cycle can thus be completed thanks to the portion of the refrigerant circulating in the fourth branch.

[0012] The different stages of the proposed control process can thus be written, according to the first example of implementation and in permanent mode: (i) providing a first flow of high-pressure refrigerant fluid at the compressor outlet and circulating the first flow of refrigerant fluid in the main loop, (ii) dividing the first flow of high-pressure refrigerant into a second flow circulating successively in the first exchanger and the fourth expansion valve, and a third flow circulating in the fourth bypass branch to the sixth expansion valve, expanding the second flow of refrigerant coming from the first exchanger to an intermediate pressure lower than the high pressure, expanding the third flow circulating in the fourth bypass branch to the intermediate pressure, the intermediate-pressure refrigerant coming from the first exchanger joining the intermediate pressure refrigerant from the fourth branch so as to form the first flow of intermediate pressure refrigerant, (iii) circulating the first flow of intermediate pressure refrigerant through the third heat exchanger, expanding the intermediate pressure refrigerant from the third exchanger to a low pressure below the intermediate pressure, the low pressure refrigerant returning to the compressor.

[0013] According to a second example of implementation of the control process: - in step (ii), the fourth expander expands the refrigerant coming from the first exchanger to a low pressure, and the sixth expander expands the refrigerant circulating in the fourth bypass branch to the low pressure, and - in step (iii), the low-pressure refrigerant from the third heat exchanger passes through the fifth expansion valve without undergoing expansion.

[0014] According to the second example of implementation of the control method, a flow rate of the interior air flow is preferably less than a predetermined threshold.

[0015] In particular, the indoor airflow rate may be zero.

[0016] In this second example of the method implementation, the high-pressure, high-temperature refrigerant from the compressor is expanded to a low-pressure state before circulating in the third exchanger. The low-pressure, high-temperature gaseous refrigerant cools in the third exchanger and releases heat. The element of the electric powertrain is thus heated. The low-pressure refrigerant from the third exchanger passes through the fifth expansion valve without changing pressure and reaches the compressor inlet. This cycle is referred to as the low pressure triangle.

[0017] The different stages of the proposed control process can thus be written, according to the second implementation example and in steady state: (i) providing a first flow of high-pressure refrigerant fluid at the compressor outlet and circulating the first flow of refrigerant fluid in the main loop, (ii) dividing the first flow of high-pressure refrigerant into a second flow circulating successively in the first exchanger and the fourth expansion valve, and a third flow circulating in the fourth bypass branch to the sixth expansion valve, expanding the second flow of refrigerant coming from the first exchanger to a low pressure lower than the high pressure, expanding the third flow circulating in the fourth bypass branch to low pressure, the low pressure refrigerant fluid coming from the first exchanger joining the low pressure refrigerant fluid coming from the fourth bypass branch so as to form the first flow of low pressure refrigerant fluid, (iii) circulating the first flow of low-pressure refrigerant fluid through the third heat exchanger, the low-pressure refrigerant fluid from the third exchanger reaching the compressor.

[0018] According to a third example of implementation of the control process: - in step (ii), the refrigerant fluid coming from the first exchanger passes through the fourth expansion valve without undergoing any expansion, and the refrigerant fluid circulating in the fourth bypass branch passes through the sixth expansion valve without undergoing any expansion, and - in step (iii), the fifth expander expands the high pressure refrigerant fluid from the third heat exchanger to a low pressure lower than the high pressure.

[0019] According to the third example of implementation of the control method, a flow rate of the indoor air flow is preferably lower than the predetermined threshold.

[0020] In particular, the indoor airflow rate may be zero.

[0021] In this third example of the method's implementation, the high-pressure, high-temperature refrigerant from the compressor circulates through the third exchanger without undergoing any prior expansion. The high-pressure, high-temperature gaseous refrigerant cools in the third exchanger and releases heat. The element of the electric powertrain is thus heated. The high pressure refrigerant from the third exchanger passes to low pressure through the fifth expansion valve and reaches the compressor inlet. This cycle is referred to as the high pressure triangle.

[0022] The different stages of the proposed control process can thus be written, according to the third implementation example and in steady state: (i) providing a first flow of high-pressure refrigerant fluid at the compressor outlet and circulating the first flow of refrigerant fluid in the main loop, (ii) dividing the first flow of high-pressure refrigerant fluid into a second flow circulating successively in the first exchanger and the fourth expansion valve of the second bypass branch (C), and a third flow circulating in the fourth bypass branch towards the sixth expansion valve, the high-pressure refrigerant fluid coming from the first exchanger joining the high-pressure refrigerant fluid coming from the fourth bypass branch so as to form the first flow of high-pressure refrigerant fluid, (iii) circulating the first flow of high pressure refrigerant through the third heat exchanger, expanding the intermediate pressure refrigerant from the third exchanger to a low pressure below the high pressure, the low pressure refrigerant from the third exchanger reaching the compressor.

[0023] The refrigerant circuit is configured to circulate a refrigerant.

[0024] The compressor moves the refrigerant from a low pressure state, at the compressor inlet, to a high pressure state, at the compressor outlet.

[0025] 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.

[0026] According to an alternative embodiment, the first heat exchanger is configured to exchange heat with a heat transfer fluid circulating in a closed 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.

[0027] According to the proposed method, the first exchanger can operate as a refrigerant fluid cooler. According to the proposed method, the third exchanger can operate as a refrigerant cooler.

[0028] The third heat exchanger can be used to heat or cool the element of the vehicle's electric powertrain. The element of the vehicle's electric powertrain can thus be maintained, or placed, in a preferred temperature range corresponding to the optimal operation of this element.

[0029] The third exchanger can be thermally inactive.

[0030] According to the proposed method, the second exchanger is thermally inactive.

[0031] The fifth connection point is located on the second branch downstream of the third exchanger and upstream of the fifth regulator.

[0032] According to an exemplary embodiment, the element of the electric powertrain of the vehicle comprises an electrical energy storage battery.

[0033] Alternatively or additionally, the element of the vehicle's electric powertrain comprises an electric vehicle traction motor.

[0034] 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.

[0035] 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.

[0036] Each regulator is for example an electronic regulator.

[0037] According to one aspect of the proposed control method, the flow rate of refrigerant in the first bypass branch is zero. The third regulator is thus in the closed position.

[0038] According to another aspect of the proposed control method, the flow rate of refrigerant circulating in the third bypass branch is zero. The first regulator is thus in the closed position. Likewise, the second regulator is in the closed position.

[0039] According to yet another aspect of the proposed control method, the flow rate of refrigerant circulating in the second exchanger is zero. The flow rate of refrigerant circulating in the main loop between the third connection point and the fourth connection point is zero.

[0040] The fourth regulator is in the open position. The fifth regulator is in the open position. The sixth regulator is in the open position.

[0041] The opening position of the fourth regulator may differ from the opening position of the fifth regulator.

[0042] The value of the so-called “high pressure” pressure at the compressor outlet is, for example, between 110 bars and 130 bars. The value of the so-called "intermediate" pressure, after expansion for example by the fourth regulator on the one hand, and by the sixth regulator on the other hand, is lower than the value of the high pressure. The intermediate pressure is for example between 40 bars and 120 bars. The value of the so-called “low pressure”, after expansion for example in the second regulator, is lower than the value of the intermediate pressure. Low pressure is for example between 35 bars and 65 bars.

[0043] According to one aspect of the proposed control method, the method comprises the steps: - determine a thermal power supplied by the first exchanger, - controlling the flow rate of refrigerant circulating in the refrigerant circuit so as to control the thermal power supplied by the first exchanger to a first target value.

[0044] The control process may include the following sub-steps: - increase the flow rate of refrigerant circulating in the refrigerant circuit if the thermal power supplied by the first exchanger is lower than the first target value, and - reduce the flow rate of refrigerant circulating in the refrigerant circuit if the thermal power supplied by the first exchanger is greater than the first target value.

[0045] The flow rate of refrigerant circulating in the refrigerant circuit is equal to the flow rate of refrigerant discharged by the compressor.

[0046] The control process may include the step: - control the compressor rotation speed in order to control the flow of refrigerant circulating in the refrigerant circuit.

[0047] The control process may include the following sub-steps: - increase the rotation speed of the compressor so as to increase the flow rate of refrigerant circulating in the refrigerant circuit, and - reduce the compressor rotation speed so as to reduce the flow of refrigerant circulating in the refrigerant circuit.

[0048] According to one embodiment, in which the compressor is an electric compressor, the method comprising the steps: - determine the electrical power absorbed by the compressor, - control the rotation speed of the compressor so as to control the electrical power absorbed by the compressor to a second target value. The second target value depends on the high pressure value and depends on the low pressure value.

[0049] The method may comprise the sub-step: - determine a value of adiabatic efficiency of the compressor.

[0050] The second target value is for example equal to the first target value divided by the determined value of an adiabatic efficiency of the compressor.

[0051] The proposed method may comprise a sub-step of determining the rotation speed of the compressor.

[0052] According to another aspect of the proposed control method, the method comprises the steps: - determine a value of the pressure of the high-pressure refrigerant fluid, - controlling an expansion of the refrigerant fluid in the fourth expansion valve so as to control the pressure of the high-pressure refrigerant fluid at a third target value.

[0053] The proposed control method may include the following sub-steps: - reduce a refrigerant passage section through the fourth expansion valve if the high-pressure refrigerant pressure is higher than the third target value, - increase a refrigerant passage section through the fourth expansion valve if the high-pressure refrigerant pressure is lower than the third target value.

[0054] According to another aspect of the proposed control method, the method comprises the steps: - determine a value of the pressure of the refrigerant fluid at low pressure, - controlling an expansion of the refrigerant fluid in the sixth expansion valve so as to control the pressure of the low-pressure refrigerant fluid at a fourth target value.

[0055] The control process may include the following sub-steps: - reduce a refrigerant passage section through the sixth expansion valve if the low-pressure refrigerant pressure is higher than the fourth target value, - increase a refrigerant passage section through the sixth expansion valve if the low-pressure refrigerant pressure is lower than the fourth target value.

[0056] According to one embodiment, in which the third heat exchanger is thermally coupled with the element of the electric powertrain of the vehicle via a heat transfer fluid which can circulate in a heat transfer fluid circuit, the flow rate of heat transfer fluid in the third exchanger is less than a predetermined threshold.

[0057] The flow rate of heat transfer fluid circulating in the third exchanger is zero. In this case, the heat exchange in the third exchanger is zero. All the heating power is thus dissipated at the first exchanger. In other words, all the heating power is allocated to the passenger compartment.

[0058] A thermal conditioning system for a motor vehicle is also proposed, comprising a refrigerant circuit comprising: a main loop successively comprising, according to 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, a first branch branch connecting a first connection point arranged on the main loop downstream of an outlet of the compressor and upstream of the first exchanger to a second connection point arranged on the main loop downstream of the second heat exchanger and upstream of the accumulation device, the first branch branch comprising a third expansion valve, a second branch branch connecting a third connection point arranged on the main loop between the first exchanger and the 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 branch successively comprising a fourth expansion valve, a third heat exchanger thermally coupled with an element of an electric powertrain of a motor vehicle, and a fifth expansion valve,a third branch branch connecting a fifth connection point arranged on the second branch 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, - an electronic control unit comprising a memory and a computer program stored on the memory, the computer program being configured to implement the method described above.

[0059] According to one embodiment, the thermal conditioning system comprises an internal exchanger configured to allow heat exchange between the refrigerant circulating between the first expansion valve and the second expansion valve and the refrigerant downstream of the accumulation device and upstream of an inlet of the compressor.

[0060] The internal exchanger is configured to allow heat exchange between the refrigerant circulating between the first expansion valve and the sixth connection point and the refrigerant downstream of the accumulation device and upstream of a compressor inlet.

[0061] 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.

[0062] According to one embodiment, the thermal conditioning system comprises a fifth bypass 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 bypass branch successively comprising a seventh expansion valve and a fourth heat exchanger configured to exchange heat with an interior air flow.

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

[0064] The main loop includes a second shutoff valve located between the second connection point and the fourth connection point.

[0065] The main loop includes a second shut-off valve located between the second connection point and the tenth connection point.

[0066] The first shut-off valve is an electrically operated valve. Similarly, the second shut-off valve is an electrically operated valve.

[0067] The refrigerant circuit comprises a first one-way valve arranged on the main loop between the first exchanger and the third connection point.

[0068] 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.

[0069] The refrigerant circuit includes a second one-way valve arranged on the third bypass branch.

[0070] 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.

[0071] The refrigerant circuit includes a third one-way valve located on the main loop between the fourth exchanger and the tenth connection point.

[0072] The third one-way valve is configured to allow refrigerant fluid to flow through the third one-way valve of the fourth exchanger to the sixth connection point.

[0073] The third one-way valve is also configured to prohibit a circulation of refrigerant fluid through the third one-way valve from the sixth connection point to the fourth exchanger.

[0074] The first one-way valve is for example a check valve.

[0075] Similarly, the second one-way valve and the third one-way valve can also be a check valve.

[0076] Alternatively, each one-way valve may be an electrically operated valve.

[0077] 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

[0078] Other features, details and advantages will become apparent upon reading the detailed description below, and upon analyzing the attached drawings, in which:

[0079] [Fig. 1] is a schematic view of a thermal conditioning system according to a first embodiment of the invention,

[0080] [Fig. 2] is a schematic view of a thermal conditioning system according to a second embodiment of the invention,

[0081] [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,

[0082] [Fig. 4] is a schematic view illustrating the operation of the thermal conditioning system of Figure 2, according to a second or third example of implementation of the proposed method,

[0083] [Fig. 5] is a diagram illustrating the operation of the thermal conditioning system of Figure 2, comparing the first, second and third examples of implementation of the proposed method,

[0084] [Fig. 6] is a block diagram of the proposed process. Description of the embodiments

[0085] 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.

[0086] 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.

[0087] 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.

[0088] When it is specified that a subsystem includes a given element, this does not exclude the presence of other elements in this subsystem.

[0089] The thermal conditioning system 100 which will be described comprises an electronic control unit 64 receiving information from various sensors measuring in particular the characteristics of the refrigerant fluid at various points in the circuit. The electronic control unit 64 also receives instructions issued by the occupants of the vehicle, for example the desired temperature inside the passenger compartment. The electronic control unit 64 can also receive instructions from other electronic subsystems, such as an electrical energy storage battery management system. The electronic control unit 64 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 64 can execute software encoding the proposed method.

[0090] 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. An electronic unit makes it possible to control the electric current supplied to the different windings of the electric motor of the compressor 7. The electric motor of the compressor 7 is, for example, a brushless motor.

[0091] The refrigerant circuit 10 forms a closed circuit in which the refrigerant can circulate. The refrigerant circuit 10 is sealed when it is in a nominal operating state, i.e. without defects or leaks. Each connection point of the circuit 10 allows the refrigerant to pass into one or other of the circuit portions joining at this connection point. The distribution of the refrigerant between the circuit portions joining at a connection point is achieved by adjusting the opening or closing of the stop valves, non-return valves or expansion devices included on each of these portions. In other words, each connection point is a means of redirecting the refrigerant arriving at this connection point. Various stop valves and non-return valves thus make it possible to selectively direct the refrigerant into the different branches of the refrigerant circuit, in order to ensure different operating modes, as will be described later.

[0092] The refrigerant used by the refrigerant circuit 10 is here a natural fluid, such as R744. It is also possible to use a chemical refrigerant, such as R1234yf, or R 134a.

[0093] 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.

[0094] 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.

[0095] 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.

[0096] The term "first exchanger" is equivalent to the term "first heat exchanger". Similarly, the term "internal exchanger" is equivalent to the term "internal heat exchanger". The term "accumulation device" is equivalent to the term "refrigerant accumulation device".

[0097] 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.

[0098] Figure 1 shows a thermal conditioning system 100 for a motor vehicle. 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 external air flow Fe to the passenger compartment of the vehicle, - a refrigerant fluid accumulation device 8. The refrigerant circuit 10 comprises a first bypass branch B connecting a first connection point 11 arranged on the main loop A downstream of an outlet 7b of the compressor 7 and upstream of the first exchanger 1 to a second connection point 12 arranged on the main loop A downstream of the second heat exchanger 2 and upstream of the accumulation device 8, the first bypass branch B comprising a third expansion valve 33. The refrigerant circuit 10 comprises a second bypass branch C connecting a third connection point 13 arranged on the main loop A between the first exchanger 1 and the first expander 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 expander 34, a third heat exchanger 3 thermally coupled with an element 25 of an electric traction chain of a motor vehicle, and a fifth expander 35. The refrigerant circuit 10 comprises a third bypass branch D connecting a fifth connection point 15 arranged on the second bypass 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. The refrigerant circuit 10 comprises a fourth bypass 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 bypass branch C downstream of the fourth expansion valve 34 and upstream of the third exchanger 3, the fourth bypass branch E comprising a sixth expansion valve 36. The thermal conditioning system 100 comprises an electronic control unit 64 configured to implement the method which will be described below.

[0099] A computer program stored in a memory may implement the proposed method. The memory may be integrated into the electronic control unit 64.

[0100] 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.

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

[0102] According to an exemplary embodiment, illustrated schematically in FIG. 2, the first heat exchanger 1 is configured to exchange heat with the interior air flow Fi in the passenger compartment of the vehicle.

[0103] 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.

[0104] According to an alternative embodiment, illustrated schematically in FIG. 1, the first heat exchanger 1 is configured to exchange heat with a heat transfer liquid circulating in a closed heat transfer liquid circuit, the heat transfer liquid circuit comprising a heat exchanger 1 A configured to exchange heat with the interior air flow Fi in the passenger compartment of the vehicle.

[0105] The second heat exchanger 2 is for example arranged on the front of the vehicle, so as to receive the outside air flow directly. The second heat exchanger 2 can be arranged just behind the grille of the vehicle.

[0106] According to the example illustrated in the various figures, the third heat exchanger 3 is thermally coupled with the element 25 of the electric traction chain by means of a heat transfer liquid circulating in a heat transfer liquid circuit 40. The heat transfer fluid circuit 40 comprises, for example, a circulation pump, not shown. When the pump is activated, the heat transfer fluid circulates in the circuit 40. When the pump is inactive, the heat transfer fluid does not circulate in the circuit 40, and the flow rate in the circuit 40 is zero. The pump is, for example, an electrically controlled pump. 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. The third heat exchanger 3 makes it possible to heat or cool 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.

[0107] The heat transfer fluid circulating in circuit 40 is, for example, a mixture of water and glycol. According to the illustrated example, circuit 30 and circuit 40 are independent, that is to say they are not connected.

[0108] 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 a 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.

[0109] The heat transfer fluid of the circuit 40 can, for example, circulate between the elements of the electrical energy storage battery, or inside the electric motor, or the casing of the electronic control unit of the electric motor. The heat transfer fluid can thus exchange heat.

[0110] The fifth connection point 15 is arranged on the second branch of bypass C downstream of the third exchanger 3 and upstream of the fifth regulator 35.

[0111] The second embodiment of the thermal conditioning system 100, illustrated in FIG. 2, also differs from the first embodiment by the presence of additional elements in the refrigerant circuit 10.

[0112] In this second embodiment, the thermal conditioning system 100 comprises 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 downstream of the accumulation device 8 and upstream of an inlet 7a of the compressor 7.

[0113] The internal exchanger 6 is configured to allow heat exchange between the refrigerant circulating between the first expansion valve 31 and the sixth connection point 16 and the refrigerant downstream of the accumulation device 8 and upstream of an inlet 7a of the compressor 7.

[0114] According to the second embodiment, the thermal conditioning system 100 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 comprising a seventh expansion valve 37 and a fourth heat exchanger 4 configured to exchange heat with an interior air flow Fi.

[0115] The fourth exchanger 4 is arranged in the heating, ventilation and / or air conditioning system of the vehicle. According to the first embodiment, the fourth exchanger 4 is arranged upstream of the exchanger 1A in a direction of flow of the interior air flow Fi. According to the second embodiment, 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 Fi and thus the passenger compartment of the vehicle to be cooled.

[0116] The presence of the fifth bypass branch F is independent of the presence of the internal exchanger 6. In other words, the thermal conditioning system 100 may include the fifth bypass branch F but not include the internal exchanger 6, and vice versa.

[0117] 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.

[0118] The main loop A comprises a first shut-off valve 41 arranged between the first connection point 11 and the seventh connection point 17.

[0119] 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.

[0120] 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 41, 42 is for example controlled by the electronic control unit 64.

[0121] 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.

[0122] 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.

[0123] 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.

[0124] According to the second embodiment, 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 sixth connection point 16. The third one-way valve 45 is also configured to prohibit circulation of refrigerant fluid through the third one-way valve 45 from the sixth connection point 16 to the fourth exchanger 4.

[0125] 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. Alternatively, each one-way valve 43, 44, 45 may be an electrically operated valve.

[0126] Each regulator 31, ..., 36 is for example an electronic regulator.

[0127] The thermal conditioning system 100 may operate in several operating modes. The proposed method, when implemented, corresponds to particular operating modes of the thermal conditioning system 100.

[0128] A method for controlling a thermal conditioning system for a motor vehicle is proposed. The thermal conditioning system 100 comprises a refrigerant circuit 10 comprising: a main loop A comprising successively, according to the direction of circulation of the refrigerant: -- a compressor 7, -- a first heat exchanger 1 thermally coupled with an interior air flow Fi to a passenger compartment of the vehicle, -- a first regulator 31, -- a second regulator 32, -- a second heat exchanger 2 configured to exchange heat with an outside air flow Fe to the passenger compartment of the vehicle, -- a refrigerant fluid accumulation device 8, 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,a third heat exchanger 3 thermally coupled with an element 25 of an electric powertrain of a motor vehicle, and a fifth expansion valve 35, 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 sixth, regulator 36. The process involves the following steps: (i) provide a flow D of high-pressure refrigerant fluid at the outlet of the compressor 7 and circulate the flow D of refrigerant fluid in the main loop A, (ii) dividing the flow D of high-pressure refrigerant into a first part P1 circulating successively in the first exchanger 1 and the fourth expansion valve 34, and a second part P2 circulating in the fourth bypass branch E towards the sixth expansion valve 36, the refrigerant coming from the fourth expansion valve 34 joining the refrigerant coming from the sixth expansion valve 36 so as to form a flow D' of refrigerant, (iii) circulating the flow D' of refrigerant fluid formed successively in the third heat exchanger 3 and in the fifth expansion valve 35, the refrigerant fluid coming from the fifth expansion valve 35 reaching the compressor 7.

[0129] The high-pressure refrigerant circulating in the first exchanger 1 can heat the interior air flow Fi and thus the passenger compartment of the vehicle. The thermal energy remaining in the refrigerant after heating the interior air flow Fi is generally insufficient to ensure sufficient heating of the element 25 of the powertrain. The flow of refrigerant circulating in the fourth branch E makes it possible to increase the energy supplied to the element 25, and thus to increase the heating power. According to the operating mode corresponding to the proposed method, the second exchanger 2 is not thermally active and does not evaporate refrigerant. The passenger compartment and the element 25 of the powertrain can thus be heated without risking icing the second exchanger 2. This operating mode is therefore particularly advantageous in cold ambient temperatures, in particular below 0°C.

[0130] The second part P2 of the flow rate D of high-pressure refrigerant fluid is complementary to the first part P1 of the flow rate D of high-pressure refrigerant fluid.

[0131] According to the proposed method, the first exchanger 1 can operate as a refrigerant fluid cooler. In other words, the refrigerant fluid can release heat by passing through the first exchanger 1. According to the proposed method, the third exchanger 3 can operate as a refrigerant fluid cooler. As previously, the refrigerant fluid can thus, under certain operating conditions, release heat by passing through the third exchanger 3. According to the proposed method, the second exchanger 2 is thermally inactive. According to the proposed method, the flow rate of refrigerant in the second exchanger 2 is zero. In other words, the refrigerant does not circulate in the second exchanger 2. There is therefore no heat exchange at the level of the second exchanger 2. The third exchanger 3 may be thermally inactive. In other words, the refrigerant may, under certain operating conditions, not carry out any heat exchange while passing through the third exchanger 3.

[0132] In steady state, the time variation of the mass of refrigerant in a heat exchanger is zero, and the flow rate of refrigerant downstream of a heat exchanger is equal to the flow rate of refrigerant upstream of this heat exchanger. Similarly, there is no accumulation of refrigerant in an expansion valve, and the flow rate of refrigerant downstream of an expansion valve is equal to the flow rate upstream of that valve. Thus, in steady state, the flow rate of refrigerant fluid at the outlet of the first exchanger 1 is equal to the flow rate of refrigerant fluid at the inlet of the first exchanger 1. Likewise, the flow rate of refrigerant fluid circulating in the fourth bypass branch E downstream of the sixth expansion valve 36 is equal to the flow rate of refrigerant fluid circulating in the fourth bypass branch E upstream of the sixth expansion valve 36. In steady state, the flow rate D' sucked in by compressor 7 is identical to the flow rate D discharged by compressor 7.

[0133] Thus, in steady state the different stages of the proposed process are: (i) supply a first flow Q1 of high-pressure refrigerant fluid at the outlet of the compressor 7 and circulate the first flow Q1 of refrigerant fluid in the main loop A, (ii) dividing the first flow Q1 of high-pressure refrigerant into a second flow Q2 circulating successively in the first exchanger 1 and the fourth expansion valve 34, and a third flow Q3 circulating in the fourth bypass branch E towards the sixth expansion valve 36, the refrigerant coming from the fourth expansion valve 34 joining the refrigerant coming from the sixth expansion valve 36 so as to form the first flow Q1 of refrigerant, (iii) circulating the first flow Q1 of refrigerant fluid successively in the third heat exchanger 3 and in the fifth expansion valve 35, the first flow Q1 of refrigerant fluid coming from the fifth expansion valve 35 reaching the compressor 7.

[0134] Figures 3 and 4 illustrate the circulation of the refrigerant in the circuit 10 when the proposed method is implemented. Figure 3 corresponds to a first example of implementation. Figure 4 corresponds to a second example and a third example. In these figures, the portions of the circuit 10 in which a flow of refrigerant circulates are in solid thick lines, while the portions in which the refrigerant does not circulate are in thin dotted lines. The different arrows indicate the direction of circulation of the refrigerant in the different portions of the refrigerant circuit 10.

[0135] Figure 5 schematically illustrates the value of the refrigerant pressure at different points in the circuit. On the vertical axis, the value designated by the HP sign represents the high pressure value, the value designated by the BP sign represents the low pressure value, and the value designated by the IP sign represents the intermediate pressure value. The diagram is not to scale and is only intended to differentiate the three pressure levels. On the horizontal axis, the sign P34a designates the pressure at the inlet 34a of the fourth regulator 34. The sign P34b designates the pressure at the outlet 34b of the fourth regulator 34, therefore after a possible expansion in the fourth regulator 34. In the same way, the sign P36a designates the inlet pressure 36a of the sixth regulator 36, and the sign P36b designates the outlet pressure 36b of the sixth regulator 36. The sign P35a designates the inlet pressure 35a of the fifth regulator 35. The sign P35b designates the outlet pressure 35b of the fifth regulator 35.

[0136] A first example of implementation of the control method makes it possible to heat the vehicle's passenger compartment.

[0137] According to the first example of implementation of the control process: - in step (ii), the fourth expander 34 expands the refrigerant coming from the first exchanger 1 to an intermediate pressure lower than the high pressure, and the sixth expander 36 expands the refrigerant circulating in the fourth bypass branch E to the intermediate pressure, and - in step (iii), the fifth expander 35 expands the intermediate pressure refrigerant fluid coming from the third heat exchanger 3 to a low pressure lower than the intermediate pressure.

[0138] According to this first example of implementation of the method, illustrated in figure 3, the high pressure refrigerant fluid circulating in the first exchanger 1 makes it possible to heat the interior airflow Fi and thus the vehicle's passenger compartment. The enthalpy of the refrigerant fluid leaving the first exchanger 1 is lower than the enthalpy of the refrigerant fluid entering the compressor 7. The thermodynamic cycle carried out by the refrigerant fluid passing through the first exchanger 1 is therefore not completed. In order to complete the thermodynamic cycle, the refrigerant fluid at intermediate pressure coming from the fourth branch of bypass E increases the enthalpy of the refrigerant fluid at the inlet of the third exchanger 3. The thermodynamic cycle is thus completed thanks to the enthalpy provided by the refrigerant fluid circulating in the fourth branch of bypass E.

[0139] According to the first example of implementation of the process, during steady-state operation, the different stages of the proposed process are written: (i) supply a first flow Q1 of high-pressure refrigerant fluid at the outlet of the compressor 7 and circulate the first flow Q1 of refrigerant fluid in the main loop A, (ii) dividing the first flow Q1 of high-pressure refrigerant into a second flow Q2 circulating successively in the first exchanger 1 and the fourth expansion valve 34, and a third flow Q3 circulating in the fourth bypass branch E towards the sixth expansion valve 36, expanding the second flow Q2 of refrigerant coming from the first exchanger 1 to an intermediate pressure lower than the high pressure, expanding the third flow Q3 circulating in the fourth bypass branch E to the intermediate pressure, the intermediate-pressure refrigerant coming from the first exchanger 1 joining the intermediate-pressure refrigerant coming from the fourth bypass branch E so as to form the first flow Q1 of intermediate-pressure refrigerant, (iii) circulating the first flow Q1 of intermediate pressure refrigerant fluid in the third heat exchanger 3, expanding the intermediate pressure refrigerant fluid coming from the third exchanger 3 to a low pressure lower than the intermediate pressure, the low pressure refrigerant fluid joining the compressor 7.

[0140] Part A of Figure 5 illustrates the level of expansion provided respectively by the fourth regulator 34, the sixth regulator 36 and the fifth regulator 35, during operation according to the first example of implementation of the method.

[0141] A second example of implementation of the control method makes it possible to heat element 25 of the vehicle's electric powertrain.

[0142] According to the second example of implementation of the control method: - in step (ii), the fourth expander 34 expands the refrigerant coming from the first exchanger 1 to a low pressure, and the sixth expander 36 expands the refrigerant circulating in the fourth bypass branch E to the low pressure, and - in step (iii), the low-pressure refrigerant fluid coming from the third heat exchanger 3 passes through the fifth expansion valve 35 without undergoing expansion.

[0143] According to the second example of implementation of the control method, a flow rate of the indoor air flow Fi is preferably less than a predetermined threshold. The predetermined threshold is for example 50kg / h (kilogram per hour). In particular, the flow rate of the indoor air flow Fi can be zero.

[0144] In this second example of implementation of the method, the high-pressure, high-temperature refrigerant fluid from the compressor 7 is expanded to a low-pressure state before circulating in the third exchanger 3. The low-pressure, high-temperature gaseous refrigerant fluid cools in the third exchanger 3 and releases heat. The element 25 of the electric powertrain is thus heated. After passing through the third exchanger 3, the low-pressure refrigerant fluid passes through the fifth expansion valve 5 without changing pressure and reaches the inlet 7a of the compressor 7. This thermodynamic cycle is referred to as the low pressure triangle.

[0145] According to the second example of implementation of the method, during steady-state operation, the different stages of the proposed control method are written: (i) supply a first flow Q1 of high-pressure refrigerant fluid at the outlet of the compressor 7 and circulate the first flow Q1 of refrigerant fluid in the main loop A, (ii) dividing the first flow Q1 of high-pressure refrigerant into a second flow Q2 circulating successively in the first exchanger 1 and the fourth expansion valve 34, and a third flow Q3 circulating in the fourth bypass branch E to the sixth expansion valve 36, expanding the second flow Q2 of refrigerant coming from the first exchanger 1 to a low pressure lower than the high pressure, expanding the third flow Q3 circulating in the fourth bypass branch E to the low pressure, the low pressure refrigerant fluid coming from the first exchanger 1 joining the low pressure refrigerant fluid coming from the fourth branch E so as to form the first flow Q1 of low pressure refrigerant fluid, (iii) circulating the first flow Q1 of low-pressure refrigerant fluid in the third heat exchanger 3, the low-pressure refrigerant fluid coming from the third exchanger 3 joining the compressor 7.

[0146] Part B of Figure 5 illustrates the level of expansion provided respectively by the fourth regulator 34, the sixth regulator 36 and the fifth regulator 3, during operation according to the second example of implementation of the method.

[0147] A third example of implementation of the control method also makes it possible to heat element 25 of the vehicle's electric powertrain.

[0148] According to the third example of implementation of the control method: - in step (ii), the refrigerant fluid coming from the first exchanger 1 passes through the fourth expansion valve 34 without undergoing any expansion, and the refrigerant fluid circulating in the fourth bypass branch E passes through the sixth expansion valve 36 without undergoing any expansion, and - in step (iii), the fifth expander 35 expands the high-pressure refrigerant fluid coming from the third heat exchanger 3 to a low pressure lower than the high pressure.

[0149] According to the third example of implementation of the control method, a flow rate of the indoor air flow Fi is preferably lower than the predetermined threshold.

[0150] In particular, the indoor airflow rate Fi may be zero.

[0151] In this third example of implementation of the method, the high-pressure, high-temperature refrigerant fluid from the compressor 7 circulates in the third exchanger 3 without undergoing prior expansion. The high-pressure, high-temperature gaseous refrigerant fluid cools in the third exchanger 3 and releases heat. The element 25 of the electric powertrain is thus heated. The high-pressure refrigerant fluid from the third exchanger 3 circulates in the second bypass branch C to the fifth expansion valve 35 and passes to low pressure by passing through the fifth expansion valve 5. The low-pressure refrigerant fluid circulates successively in the accumulator 8, in the internal exchanger 6, and joins the inlet 7a of compressor 7. This cycle is referred to as the high pressure triangle.

[0152] According to the third example of implementation of the method, the different stages of the proposed control method are written during steady-state operation: (i) supply a first flow Q1 of high-pressure refrigerant fluid at the outlet of the compressor 7 and circulate the first flow Q1 of refrigerant fluid in the main loop A, (ii) dividing the first flow Q1 of high-pressure refrigerant into a second flow Q2 circulating successively in the first exchanger 1 and the fourth expansion valve 34, and a third flow Q3 circulating in the fourth bypass branch E towards the sixth expansion valve 36, the high-pressure refrigerant coming from the first exchanger 1 joining the high-pressure refrigerant coming from the fourth bypass branch E so as to form the first flow Q1 of high-pressure refrigerant, (iii) circulating the first flow Q1 of high-pressure refrigerant fluid in the third heat exchanger 3, expanding the intermediate-pressure refrigerant fluid from the third exchanger 3 to a low pressure lower than the high pressure, the low-pressure refrigerant fluid from the third exchanger 3 joining the compressor 7.

[0153] Part C of Figure 5 illustrates the level of expansion provided respectively by the fourth regulator 34, the sixth regulator 36 and the fifth regulator 35, during operation according to the third example of implementation of the method.

[0154] According to the first example of implementation of the process: - the first exchanger 1 operates as a refrigerant fluid cooler, - the third exchanger 3 is thermally inactive.

[0155] According to the second and third examples of implementation of the process: - the first exchanger 1 is thermally inactive. - the third exchanger 3 operates as a refrigerant fluid cooler.

[0156] According to the proposed method, the second exchanger 2 is thermally inactive. In other words, depending on the operation corresponding to the first, second or third example, the second exchanger 2 does not participate in the heat exchanges. Likewise, the fourth exchanger 4 is thermally inactive, since it is not crossed by a flow of refrigerant fluid. The internal exchanger 6 does not participate in heat exchanges either, since the first heat exchange section 6a is not crossed by a flow of refrigerant fluid.

[0157] When the proposed method is implemented, the flow rate of refrigerant fluid in the first branch of bypass B is zero. The third regulator 33 is thus in the closed position. Similarly, the flow rate of refrigerant circulating in the third branch of bypass D is zero. The first regulator 31 is thus in the closed position. The second regulator 32 is also in the closed position. Similarly, the flow rate of refrigerant circulating in the second exchanger 2 is zero. The flow rate of refrigerant circulating in the main loop A between the third connection point 13 and the fourth connection point 16 is zero.

[0158] The fourth regulator 34 is in the open position. The opening of the fourth regulator 34 can be partial or total. The fifth regulator 35 is in the open position. The opening of the fifth regulator 35 can be partial or total. The sixth regulator 36 is in the open position. The opening of the sixth regulator 36 can be partial or total. The opening position of the fourth regulator 34 may differ from the opening position of the fifth regulator 35.

[0159] According to the first example of implementation of the process: The value of the so-called “high pressure” pressure, at the outlet of compressor 7, is for example between 110 bars and 130 bars. The value of the so-called "intermediate" pressure, after expansion for example by the fourth regulator 34 on the one hand, and by the sixth regulator 36 on the other hand, is lower than the value of the high pressure. The intermediate pressure is for example between 40 bars and 120 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 35 bars and 65 bars.

[0160] We will now describe various aspects of the control methods used when the method according to the first example is implemented. According to this first example, heating of the passenger compartment is carried out.

[0161] The proposed control method includes the following steps: - determine a thermal power Pw1 supplied by the first exchanger 1, - controlling the flow rate D of refrigerant circulating in the refrigerant circuit 10 so as to control the thermal power Pw1 supplied by the first exchanger 1 to a first target value.

[0162] When the thermal couple between the first exchanger 1 and the indoor air flow is direct, the thermal power Pw1 supplied by the first exchanger 1 is determined from a value of the flow rate of the indoor air flow Fi and a value of the increase in temperature of the indoor air flow Fi when passing through the first exchanger 1. When the thermal couple between the first exchanger 1 and the indoor air flow is indirect, the flow rate of the indoor air flow Fi and the temperature increase are those occurring when crossing the exchanger 1A.

[0163] The control process includes the following sub-steps: - increase the flow rate D of refrigerant circulating in the refrigerant circuit 10 if the thermal power Pw1 supplied by the first exchanger 1 is lower than the first target value, and - reduce the flow rate Q1 of refrigerant circulating in the refrigerant circuit 10 if the thermal power Pw1 supplied by the first exchanger 1 is greater than the first target value.

[0164] The flow rate of refrigerant circulating in the refrigerant circuit 10 is equal to the flow rate of refrigerant discharged by the compressor 7.

[0165] The flow rate of refrigerant delivered by the compressor 7 depends on the rotation speed, or rotation rate, of the compressor 7. The control process thus includes the step: - control the rotation speed of the compressor 7 in order to control the flow of refrigerant circulating in the refrigerant circuit 10.

[0166] The control process includes the following sub-steps: - increase the rotation speed of the compressor 7 so as to increase the flow rate D of refrigerant circulating in the refrigerant circuit 10, and - reduce the rotation speed of the compressor 7 so as to reduce the flow rate D of refrigerant circulating in the refrigerant circuit 10.

[0167] According to the illustrated example in which the compressor 7 is an electric compressor, the method comprising the steps: - determine an electrical power Pe absorbed by the compressor 7, - control the rotation speed N of the compressor 7 so as to control the electrical power Pe absorbed by the compressor 7 to a second target value. The second target value depends on the high pressure value and depends on the low pressure value.

[0168] The method may comprise the sub-step: - determine a value of an adiabatic efficiency of the compressor 7.

[0169] The second target value is for example equal to the first target value divided by the determined value of an adiabatic efficiency of the compressor 7.

[0170] The value of the adiabatic efficiency of the compressor 7 is for example determined from the rotation speed of the compressor 7 and from a flow rate circulating in the compressor 7. The value of the adiabatic efficiency of compressor 7 is for example read in a map with two input variables. One of the input variables is the rotation speed of compressor 7 and the other input variable is the flow rate circulating in compressor 7. Correction terms to take into account other parameters can be added. The value of the adiabatic efficiency of compressor 7 is greater than 0.90, for example equal to 0.95.

[0171] The proposed method comprises a sub-step of determining the rotation speed of the compressor 7.

[0172] According to another aspect of the proposed control method, the method comprises the steps: - determine a value of the pressure P1 of the high-pressure refrigerant fluid, - controlling an expansion of the refrigerant fluid in the fourth expansion valve 34 so as to control the pressure P1 of the refrigerant fluid 10 at high pressure to a third target value.

[0173] The proposed control method includes the following sub-steps: - reducing a passage section of the refrigerant fluid through the fourth expansion valve 34 if the pressure P1 of the high-pressure refrigerant fluid 10 is greater than the third target value, - increasing a passage section of the refrigerant fluid through the fourth expansion valve 34 if the pressure P1 of the high-pressure refrigerant fluid 10 is lower than the third target value.

[0174] According to another aspect, the method comprises the steps: - determine a value of the pressure P8 of the low pressure refrigerant, - controlling an expansion of the refrigerant fluid in the sixth expansion valve 36 so as to control the pressure P8 of the refrigerant fluid 10 at low pressure to a fourth target value.

[0175] The control process includes the following sub-steps: - reduce a passage section of the refrigerant fluid through the sixth expansion valve 36 if the pressure P8 of the refrigerant fluid 10 at low pressure is higher than the fourth target value, - increasing a passage section of the refrigerant fluid through the sixth expansion valve 36 if the pressure P8 of the refrigerant fluid 10 at low pressure is lower than the fourth target value.

[0176] According to the illustrated example, the third heat exchanger 3 is thermally coupled with the element 25 of the electric drive train of the vehicle by means of a heat transfer liquid which can circulate in a heat transfer liquid circuit 40. According to the first example of implementation of the method, the flow rate QL of heat transfer liquid in the third exchanger 3 is less than a predetermined threshold.

[0177] In other words, the flow rate of heat transfer fluid circulating in the third exchanger 3 is very low so as to limit the heat exchange in the third exchanger 3 as much as possible. The flow rate QL of heat transfer fluid circulating in the third exchanger 3 is for example zero. In this case, the heat exchange in the third exchanger 3 is zero. All the heating power is thus dissipated at the level of the first exchanger 1. In other words, all the heating power supplied by the thermal conditioning system is dedicated to the passenger compartment. According to the example illustrated, the flow rate of heat transfer liquid in the circuit 40 is zero. For this, the circulation pump of the circuit 40 is kept stopped. In the case not shown where the circuit 40 comprises several circulation branches arranged in parallel, the circulation in the branch containing the third exchanger 3 can be stopped by a stop valve.

[0178] The method comprises a sub-step: - determine a flow rate QL of heat transfer fluid circulating in the heat transfer fluid circuit 40.

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), 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 expander (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 expander (34), a third heat exchanger (3) thermally coupled with an element (25) of an electric powertrain of a motor vehicle, and a fifth expander (35), 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 connection (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 sixth regulator (36), the method comprising the steps: (i) providing a flow rate (Q) of high-pressure refrigerant fluid at the outlet of the compressor (7) and circulating the flow rate (Q) of refrigerant fluid in the main loop (A), (ii) dividing the flow rate (Q) of high-pressure refrigerant into a first part (P1) circulating successively in the first exchanger (1) and the fourth expansion valve (34) of the second bypass branch (C), and a second part (P2) circulating in the fourth bypass branch (E) towards the sixth expansion valve (36), the refrigerant coming from the fourth expansion valve (34) joining the refrigerant coming from the sixth expansion valve (36) so as to form a flow rate (D') of refrigerant, (iii) circulating the flow (D') of refrigerant fluid formed successively in the third heat exchanger (3) and in the fifth expansion valve (35), the refrigerant fluid coming from the fifth expansion valve (35) reaching the compressor (7).

2. A control method according to claim 1, wherein: - in step (ii), the fourth expander (34) expands the refrigerant coming from the first exchanger (1) to an intermediate pressure lower than the high pressure, and the sixth expander (36) expands the refrigerant circulating in the fourth bypass branch (E) to the intermediate pressure, and - in step (iii), the fifth expander (35) expands the intermediate pressure refrigerant fluid coming from the third heat exchanger (3) to a low pressure lower than the intermediate pressure.

3. A control method according to claim 1, wherein: - in step (ii), the fourth expander (34) expands the refrigerant coming from the first exchanger (1) to a low pressure, and the sixth expander (36) expands the refrigerant circulating in the fourth bypass branch (E) to the low pressure, and - in step (iii), the low-pressure refrigerant fluid from the third heat exchanger (3) passes through the fifth expansion valve (35) without undergoing expansion.

4. A control method according to claim 1, wherein: - in step (ii), the refrigerant fluid coming from the first exchanger (1) passes through the fourth expansion valve (34) without undergoing expansion, and the refrigerant fluid circulating in the fourth bypass branch (E) passes through the sixth regulator (36) without undergoing any relaxation, and - in step (iii), the fifth expander (35) expands the high pressure refrigerant fluid coming from the third heat exchanger (3) to a low pressure lower than the high pressure.

5. Control method according to one of the preceding claims, in which: - the flow rate of refrigerant circulating in the first bypass branch (B) is zero, - the flow rate of refrigerant circulating in the third bypass branch (D) is zero, and - the flow rate of refrigerant circulating in the second exchanger (2) is zero.

6. Control method according to one of the preceding claims, comprising the steps: - determine a thermal power (Pw1) supplied by the first exchanger (1), - controlling the flow rate (Q) of refrigerant circulating in the refrigerant circuit (10) so as to control the thermal power (Pw1) supplied by the first exchanger (1) to a first target value.

7. Control method according to the preceding claim, comprising the sub-steps: - increasing the flow rate (Q) of refrigerant circulating in the refrigerant circuit (10) if the thermal power (Pw1) supplied by the first exchanger (1) is lower than the first target value, and - reduce the flow rate (Q) of refrigerant circulating in the refrigerant circuit (10) if the thermal power (Pw1) supplied by the first exchanger (1) is greater than the first target value.

8. Control method according to one of the preceding claims, comprising the step: - control the rotation speed of the compressor (7) in order to control the flow of refrigerant circulating in the refrigerant circuit (10).

9. Control method according to one of the preceding claims, in which the compressor (7) is an electric compressor, the method comprising the steps: - determine an electrical power (Pe) absorbed by the compressor (7), - controlling the rotation speed (N) of the compressor (7) so as to control the electrical power (Pe) absorbed by the compressor (7) to a second target value.

10. Control method according to one of the preceding claims, comprising the steps: - determine a value of the pressure (P1) of the high-pressure refrigerant, - controlling an expansion of the refrigerant fluid in the fourth expansion valve (34) so as to control the pressure (P1) of the refrigerant fluid (10) at high pressure to a third target value.

11. Control method according to the preceding claim, comprising the sub-steps: - reducing a passage section of the refrigerant fluid through the fourth expansion valve (34) if the pressure (P1) of the refrigerant fluid (10) at high pressure is higher than the third target value, - increasing a passage section of the refrigerant fluid through the fourth expansion valve (34) if the pressure (P1) of the refrigerant fluid (10) at high pressure is lower than the third target value.

12. Control method according to one of the preceding claims, comprising the steps: - determine a value of the pressure (P8) of the low pressure refrigerant, - controlling an expansion of the refrigerant fluid in the sixth expansion valve (36) so as to control the pressure (P8) of the refrigerant fluid (10) at low pressure to a fourth target value.

13. Control method according to the preceding claim, comprising the sub-steps: - reducing a passage section of the refrigerant fluid through the sixth expansion valve (36) if the pressure (P8) of the refrigerant fluid (10) at low pressure is higher than the fourth target value, - increasing a passage section of the refrigerant fluid through the sixth expansion valve (36) if the pressure (P8) of the refrigerant fluid (10) at low pressure is lower than the fourth target value.

14. Control method according to the preceding claim, in which the third heat exchanger (3) is thermally coupled with the element (25) of the electric traction chain of the vehicle by means of a heat transfer liquid which can circulate in a heat transfer liquid circuit (40), and in which the flow rate (QL) of heat transfer liquid in the third exchanger (3) is less than a predetermined threshold.

15. Thermal conditioning system (100) for a motor vehicle, comprising a refrigerant circuit (10) comprising: a main loop (A) successively comprising, according to the direction of circulation of the refrigerant: -- a compressor (7), -- a first heat exchanger (1) thermally coupled with an interior air flow (Fi) to a passenger compartment of the vehicle, -- a first regulator (31), -- a second regulator (32), -- a second heat exchanger (2) configured to exchange heat with an external air flow (Fe) to the passenger compartment of the vehicle, -- a refrigerant fluid accumulation device (8), a first 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 bypass 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 bypass branch (C) successively comprising a fourth expansion valve (34), a third heat exchanger (3) thermally coupled with an element (25) of an electric traction chain of a motor vehicle, and a fifth expansion valve (35), 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 sixth regulator (36), - an electronic control unit (64) comprising a memory and a computer program stored on the memory, the computer program being configured to implement the method according to one of the preceding claims, - an internal exchanger (6) configured to allow heat exchange between the refrigerant circulating between the first expansion valve (31) and the second expansion valve (32) and the refrigerant downstream of the accumulation device (8) and upstream of an inlet (7a) of the compressor (7), - 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).

16. Computer program stored in a memory and configured to implement the method according to any one of claims 1 to 14.

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