FR3158261A1 - Method for controlling a thermal conditioning system for a motor vehicle - Google Patents

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) successively comprising:- a compressor (7),- a first heat exchanger (1,- a first expansion valve (31),- a second expansion valve (32),- a second heat exchanger (2),- A first bypass branch (B),- A second bypass branch (C),- A third bypass branch (D),- A fourth bypass branch (E), the method comprising the steps:(ii) circulating a first flow rate (Q1) of refrigerant at high pressure in the first exchanger (1),(iii) circulating the refrigerant coming from the first exchanger (1) in the third exchanger (3),(iv) expanding the first flow rate (Q1) of refrigerant in the second expansion valve (32) to a low pressure,(v) circulating the refrigerant at low pressure in the second exchanger (2). Abstract figure: Figure 4

Description

Method for controlling a thermal conditioning system for a motor vehicle

The present invention relates to the field of thermal conditioning systems. Such systems can, for example, be fitted to motor vehicles. These systems provide thermal regulation for 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 the refrigerant to circulate in the circuit.

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 generally make it possible to perform many different functions, depending on the heat exchangers present on the part of the circuit in which the refrigerant can circulate, and depending on the expansion rate provided by each of the expansion devices present upstream of these exchangers. Possible operating modes include heating the vehicle cabin and cooling it, as well as cooling the electrical energy storage battery, for example during its electrical energy charging.

To optimize battery operation in cold conditions, it may be advantageous to also be able to heat the battery. When the passenger compartment and battery need to be heated simultaneously, it can be difficult to have sufficient heating power to ensure the heating of both components. In addition, controlling this joint heating phase of the battery and the passenger compartment can be tricky. In particular, precise distribution of the total heating power between the passenger compartment and the battery can be difficult to achieve.

It is therefore desirable to be able to simultaneously heat the vehicle interior and the electrical energy storage battery, with improved operation compared to known systems.

Summary

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, depending on the direction of circulation of the refrigerant fluid:
-- a compressor,
-- a first heat exchanger thermally coupled with an air flow inside a passenger compartment of the vehicle,
-- a first regulator,
-- a second regulator,
-- a second heat exchanger configured to exchange heat with an air flow outside the vehicle passenger compartment,
-- a refrigerant fluid accumulation device,
- a first bypass branch connecting a first connection point arranged on the main loop downstream of a compressor outlet and upstream of the first exchanger to a second connection point arranged on the main loop downstream of the second heat exchanger and upstream of the accumulation device, the first bypass branch comprising a third expansion valve,
- a second branch connection 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 connection successively comprising a fourth expansion valve and a third heat exchanger thermally coupled with an element of an electric traction chain of a motor vehicle,
- a third branch connection connecting a fifth connection point located on the second branch connection downstream of the third exchanger and upstream of the fourth connection point to a sixth connection point located on the main loop between the first regulator and the second regulator,
- a fourth branch connection connecting a seventh connection point located on the main loop downstream of the first connection point and upstream of the first exchanger to an eighth connection point located on the second branch connection downstream of the fourth regulator and upstream of the third exchanger, the fourth branch connection comprising a fifth regulator,
the process comprising the steps:
(i) provide a first flow of high-pressure refrigerant fluid at the compressor outlet,
(ii) circulating at least part of the first flow of high-pressure refrigerant fluid in the first exchanger,
(iii) circulating the refrigerant fluid from the first exchanger in the third exchanger,
(iv) circulating the first flow of refrigerant fluid through the second expansion valve and expanding the first flow to a low pressure lower than the high pressure,
(v) circulate the refrigerant at low pressure in the second exchanger.

The high-pressure refrigerant circulating in the first exchanger allows the interior airflow to be heated on demand. After passing through the first exchanger, the refrigerant can also heat the element of the electric powertrain, at the third exchanger. The refrigerant from the first exchanger can, depending on an operating mode, be joined by refrigerant circulating in the fourth branch. This refrigerant coming from the fourth branch increases the thermal energy supplied to the element of the electric powertrain. By adjusting the distribution of the refrigerant flow rates circulating respectively in the first exchanger and in the fourth branch, it is possible to control the heating power of the passenger compartment and the battery.

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

The refrigerant circuit is configured to circulate a refrigerant.

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

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.

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.

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

According to the proposed method, the second exchanger operates as a refrigerant evaporator.

According to the proposed method, the third exchanger operates as a refrigerant cooler.

The third heat exchanger is used to heat the vehicle's electric powertrain element. This allows the vehicle's electric powertrain element to be maintained, or placed, in a preferred temperature range corresponding to the optimal operation of this element.

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

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

Alternatively or additionally, the element of the vehicle's electric drive train comprises an electronic unit for controlling the vehicle's electric traction motor.

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.

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

Each regulator is for example an electronic regulator.

According to the proposed method, the low pressure refrigerant fluid from the second exchanger reaches the compressor.

According to one aspect of the proposed method, the flow rate of refrigerant fluid in the first bypass branch is zero.

The third regulator is thus in the closed position.

According to another aspect of the proposed method, the flow rate of refrigerant fluid circulating in the second bypass branch between the fifth connection point and the fourth connection point is zero.

The sixth regulator is thus in the closed position.

According to yet another aspect of the proposed method, the flow rate of refrigerant circulating in the main loop between the third connection point and the sixth connection point is zero.

The first regulator is thus in the closed position.

According to an example of implementation of the proposed method, the flow rate of refrigerant fluid in the fourth bypass branch is zero.

This operating mode can be used, for example, when the temperature of the drive train element is low, for example below 0°C. In this case, the refrigerant from the first exchanger may be sufficient to heat the drive train element. In this operating mode, in which the first exchanger and the third exchanger are connected in series on the refrigerant circuit, the coefficient of performance is particularly advantageous.

The fifth regulator is in this case in the closed position.

In this operating mode, the refrigerant flow rate is identical in the first exchanger, the third exchanger and the second exchanger.

According to other examples of implementation of the proposed method, the first flow of high-pressure refrigerant fluid is divided into a second flow circulating in the main loop and a third flow circulating in the fourth bypass branch.

In this case, a portion of the high-pressure, high-temperature refrigerant can be directed to the fourth branch and joins the refrigerant coming from the first exchanger. The refrigerant flowing through the fourth branch increases the thermal energy supplied to the element of the electric powertrain and thus increases the heating power supplied to this element. This type of operation can be implemented, for example, when the temperature of the element of the powertrain is greater than or equal to the temperature of the refrigerant coming from the first exchanger. This refrigerant is then unable to heat the element of the powertrain. The heating of this element is then provided by the refrigerant circulating in the fourth branch.

In this mode of operation, the flow rate of refrigerant in the first exchanger is lower than the flow rate of refrigerant in the third exchanger.
The refrigerant flow rate in the third exchanger is identical to the refrigerant flow rate in the second exchanger.

According to a case of implementation of the proposed method, the second flow of refrigerant fluid passes through the fourth expansion valve without undergoing expansion, and
the third flow of refrigerant fluid passes through the fifth expansion valve without undergoing expansion.
An indoor airflow rate may be zero.
In this case, there is no heat exchange in the first exchanger.

This operating mode allows the drive train element to be heated with high-pressure, high-temperature refrigerant.

In other words, the refrigerant circulating in the third exchanger is at high pressure.

According to another case of implementation of the proposed method, the fourth expander expands the second flow of refrigerant fluid to an intermediate pressure lower than the high pressure and higher than the low pressure, and the fifth expander expands the third flow of refrigerant fluid to an intermediate pressure.

In this operating case, the operation of the first exchanger and that of the third exchanger are decoupled. In fact, the pressure of the refrigerant in the third exchanger can be controlled independently of the pressure in the first exchanger. It is thus possible to adjust the temperature level in the two heat exchangers independently. In addition, the distribution of the thermal power between the two exchangers can thus be adjusted on demand by controlling the respective openings of the fourth expansion valve and the fifth expansion valve. The heating power supplied by the first exchanger and the heating power supplied by the third exchanger can thus be controlled independently of each other.

In other words, the refrigerant circulating in the third exchanger is at intermediate pressure. The value of the intermediate pressure is adjusted according to the temperature of the element of the traction chain.

The fourth regulator is thus in the partially open position.
Likewise, the fifth regulator is in the partially open position.
The opening position of the fourth expansion valve may differ from the opening position of the fifth expansion valve. The opening position of the fourth expansion valve and the opening position of the fifth expansion valve are adjusted according to a thermal power to be supplied respectively by the first exchanger and by the third exchanger.

The value of the so-called “high pressure” pressure, at the compressor outlet, is for example between 80 bars and 120 bars.
The value of the so-called "intermediate" pressure, after expansion for example by the first regulator, is lower than the value of the high pressure. The intermediate pressure is for example between 25 bars and 70 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 10 bars and 40 bars.

According to an example of implementation of the control method, the third heat exchanger is thermally coupled with the element of the electric powertrain of the vehicle by means of a heat transfer fluid circulating in a heat transfer fluid circuit, and the method comprises the steps:
- determine the temperature of the heat transfer fluid at the outlet of the third exchanger.

The control process may include the step:
- control the first flow rate of refrigerant circulating in the refrigerant circuit so as to control the temperature of the heat transfer liquid at the outlet of the third exchanger to a first target value.

The control process can thus include the following sub-steps:
- increase the flow rate of refrigerant circulating in the refrigerant circuit if the temperature of the heat transfer liquid at the outlet of the third exchanger is lower than the first target value, and
- reduce the flow rate of refrigerant circulating in the refrigerant circuit if the temperature of the heat transfer liquid at the outlet of the third exchanger is higher than the first target value.

The control process thus includes the sub-step:
- control the compressor rotation speed in order to control the flow of refrigerant circulating in the refrigerant circuit.

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

The control process includes 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 rate of refrigerant circulating in the refrigerant circuit.

The control process may include the steps:
- determine a value of the pressure of the high-pressure refrigerant fluid,
- controlling an expansion of the refrigerant fluid in the second expansion valve so as to control the pressure of the high-pressure refrigerant fluid at a second target value.

The process can thus include the following sub-steps:
- reduce a refrigerant passage section through the second expansion valve if the high-pressure refrigerant pressure is higher than the second target value,
- increase a refrigerant passage section through the second expansion valve if the high-pressure refrigerant pressure is lower than the second target value.

According to an exemplary implementation of the control method, the second target value depends on the first target value and a flow rate of heat transfer fluid in the third exchanger.

According to an example of implementation of the control process:
- the fourth regulator is in the maximum opening position,
- the fifth regulator is in the maximum opening position.

According to an example of implementation, the control method comprises the steps:
- determine the temperature of the interior air flow downstream of the first exchanger,
- controlling the first flow rate of refrigerant circulating in the refrigerant circuit so as to control the temperature of the interior air flow downstream of the first exchanger to a third target value.

According to this implementation example, the control method may include the steps:
- control an expansion of the refrigerant fluid in the fourth expansion valve so as to control the temperature of the heat transfer fluid at the outlet of the third exchanger to a fourth target value.

The process can thus include the following sub-steps:
- reduce a passage section of the refrigerant fluid through the fourth expansion valve if the temperature of the heat transfer fluid at the outlet of the third exchanger is higher than the fourth target value,
- increase a passage section of the refrigerant fluid through the fourth expansion valve if the temperature of the heat transfer fluid at the outlet of the third exchanger is lower than the fourth target value.

According to another example of implementation of the control method, the method comprises the steps:
- determine a total thermal power supplied jointly by the first exchanger and by the third exchanger,
- control the first flow rate of refrigerant circulating in the refrigerant circuit so as to control at a fifth target value the total thermal power supplied jointly by the first exchanger and by the third exchanger.

The control process can thus include the following sub-steps:
- increase the first flow rate of refrigerant circulating in the refrigerant circuit if the total thermal power supplied jointly by the first exchanger and by the third exchanger is less than the fifth target value, and
- reduce the first flow rate of refrigerant circulating in the refrigerant circuit if the total thermal power supplied jointly by the first exchanger and by the third exchanger is greater than the fifth target value.

According to this implementation example, the control method may include the steps:
- determine the temperature of the interior air flow downstream of the first exchanger,
- control an expansion of the refrigerant fluid in the fourth expansion valve so as to control the temperature of the interior air flow downstream of the first exchanger to a sixth target value.

According to this implementation example, the control method may include the following sub-steps:
- reduce a flow section of the refrigerant fluid through the fourth expansion valve if the determined temperature of the interior air flow downstream of the first exchanger is higher than the sixth target value,
- increase a refrigerant fluid passage section through the fourth expansion valve if the determined temperature of the indoor air flow downstream of the first exchanger is lower than the sixth target value.

According to another aspect of this exemplary implementation, the control method may comprise the steps:
- control an expansion of the refrigerant fluid in the fifth expansion valve so as to control the temperature of the heat transfer fluid at the outlet of the third exchanger to a seventh target value.

The control process can thus include the following sub-steps:
- reduce a passage section of the refrigerant fluid through the fifth expansion valve if the determined temperature of the heat transfer fluid at the outlet of the third exchanger is higher than the seventh target value,
- increase a passage section of the refrigerant fluid through the fifth expansion valve if the determined temperature of the heat transfer fluid at the outlet of the third exchanger is lower than the seventh target value.

According to yet another aspect of this exemplary implementation, in which the refrigerant fluid circulating in the third exchanger is in a subcritical state, the control method may comprise the steps:
- determine sub-cooling of the refrigerant fluid at the outlet of the third exchanger,
- - control a section of passage of the refrigerant fluid through the second expansion valve so as to adjust the subcooling of the refrigerant fluid at the outlet of the third exchanger to an eighth target value.
In this case, the intermediate pressure is, for example, less than 65 bars.

The control process can thus include the following sub-steps:
- increase a passage section of the refrigerant fluid through the second expansion valve if the determined subcooling of the refrigerant fluid at the outlet of the third exchanger is greater than the eighth target value,
- reduce a passage section of the refrigerant fluid through the second expansion valve if the determined subcooling of the refrigerant fluid at the outlet of the third exchanger is lower than the eighth target value.

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

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 a compressor inlet.

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.

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.

The main loop includes a first shut-off valve arranged between the first connection point and the seventh connection point.

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

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

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

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.

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

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

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

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.

The third one-way valve is also configured to prohibit the flow of refrigerant fluid through the third one-way valve from the sixth connection point to the fourth exchanger.

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

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

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

The disclosure also relates to a computer program stored in a memory and configured to implement the method described above.

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

FIG. 1 is a schematic view of a thermal conditioning system according to a first embodiment of the invention,

FIG. 2 is a schematic view of a thermal conditioning system according to a second embodiment of the invention,

FIG. 3 is a schematic view illustrating the operation of the thermal conditioning system of the FIG. 2 , according to a first example of implementation of the proposed method,

FIG. 4 is a schematic view illustrating the operation of the thermal conditioning system of the FIG. 2 , according to a second example of implementation of the proposed method,

FIG. 5 is a schematic view illustrating the operation of the thermal conditioning system of the FIG. 2 , according to a third example of implementation of the proposed method,

FIG. 6 is a block diagram of the proposed process.

To facilitate reading the figures, the different elements are not necessarily represented to scale. In these figures, identical elements bear the same references. Some elements or parameters may be indexed, i.e. designated for example by first element or second element, or first parameter and second parameter, etc. This indexing 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.

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.

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.

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

The thermal conditioning system 100 which will be described comprises an electronic control unit 63 receiving information from various sensors measuring in particular the characteristics of the refrigerant fluid at various points in the circuit. The electronic control unit 63 also receives instructions issued by the occupants of the vehicle, for example the desired temperature inside the passenger compartment. The electronic control unit 63 can also receive instructions from other electronic subsystems, such as a system for managing electrical energy storage batteries. The electronic control unit 63 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 63 can execute software encoding the proposed method.

A compression device 7, 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 7a side to a high pressure on the outlet 7b side. After expansion in one or more expansion members and after circulation in at least part of the circuit 10, the refrigerant fluid returns to the inlet 7a of the compressor 7 and begins a new thermodynamic cycle.

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 portions of the circuit 10 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 circuit 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 on demand, as will be described later.

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.

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.

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 system, frequently referred to by the English term "HVAC", for "Heating, Ventilating and Air Conditioning". This system 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 system in order to increase the flow rate of the interior air flow Fi if necessary.

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, 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 and by the second motor-fan unit can be adjusted in real time according to the heat exchange requirements, for example by the electronic unit 63 for controlling the thermal conditioning system 100.

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". The term "compression device" is equivalent to the term "compressor".

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.

It has been represented on the FIG. 1 a 100 thermal conditioning system 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 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 traction chain of a motor vehicle.
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 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 63 configured to implement the method which will be described below.

A computer program stored in a memory can implement the proposed method. The memory can be integrated into the electronic control unit 63.

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

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

According to an example of realization, shown diagrammatically on the FIG. 2 , the first heat exchanger 1 is configured to exchange heat with the interior air flow Fi to the passenger compartment of the vehicle.

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.

According to another example of realization, shown diagrammatically on the FIG. 1 , the first heat exchanger 1 is configured to exchange heat with a heat transfer fluid circulating in a closed circuit 30 of heat transfer fluid, the circuit 30 of heat transfer fluid comprising a heat exchanger 1A configured to exchange heat with the interior air flow Fi in the passenger compartment of the vehicle.

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 circulating in 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.

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

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.
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.

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 heat transfer fluid circulating in the circuit 40 is, for example, a mixture of water and glycol.

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.

The heat transfer fluid of circuit 40 can, for example, circulate between the elements of the battery, or inside the wall of the electric motor casing.

According to the example illustrated, the second branch C comprises a sixth regulator 36 arranged between the fourth connection point 14 and the fifth connection point 15.

According to the proposed method, the first exchanger 1 operates as a refrigerant fluid cooler.
According to the proposed method, the second exchanger 2 operates as a refrigerant fluid evaporator.

According to the proposed method, the third exchanger 3 operates 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 a mode of operation not shown, the third exchanger 3 can operate as a refrigerant fluid evaporator.

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

According to 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.

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.

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

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 first 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 can cool the interior air flow Fi and thus the vehicle interior.

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

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.

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

In the first embodiment corresponding to the FIG. 1 , the main loop A comprises a second shut-off valve 42 arranged between the second connection point 12 and the fourth connection point 14.
In the second embodiment corresponding to the FIG. 2 , the main loop A comprises a second shut-off valve 42 arranged between the second connection point 12 and the tenth connection point 20.

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 63.

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.

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.

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.

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.

Each regulator 31, …, 37 is for example an electronic regulator.

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.

A method for controlling a thermal conditioning system 100 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 of the refrigerant fluid:
-- a compressor 7,
-- a first heat exchanger 1 thermally coupled with an interior air flow Fi to a passenger compartment of the vehicle,
-- a first regulator 31,
-- a second regulator 32,
-- a second heat exchanger 2 configured to exchange heat with an outside air flow Fe to the passenger compartment of the vehicle,
-- a refrigerant fluid accumulation device 8,
- 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 traction chain of a motor vehicle,
- a third branch D connecting a fifth connection point 15 arranged on the second 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.
The process comprising the steps:
(i) provide a first flow Q1 of high-pressure refrigerant fluid at the outlet of the compressor 7,
(ii) circulating at least part of the first flow Q1 of high-pressure refrigerant fluid in the first exchanger 1,
(iii) circulating the refrigerant fluid from the first exchanger 1 in the third exchanger 3,
(iv) circulating the first flow Q1 of refrigerant fluid in the second expansion valve 32 and expanding the first flow Q1 to a low pressure lower than the high pressure,
(v) circulating the refrigerant at low pressure in the second exchanger 2.

The high-pressure refrigerant circulating in the first exchanger 1 makes it possible to heat the interior air flow Fi on demand. After passing through the first exchanger 1, the refrigerant can also heat the element 25 of the electric powertrain, at the third exchanger 3. The refrigerant coming from the first exchanger 1 can, depending on one operating mode, be joined by refrigerant circulating in the fourth branch E. This refrigerant coming from the fourth branch E increases the thermal energy supplied to the element 25 of the electric powertrain. By adjusting the distribution of the refrigerant flow rates circulating respectively in the first exchanger 1 and in the fourth branch E, it is possible to control the heating power supplied to the passenger compartment as well as that supplied to the battery.

The high-pressure refrigerant fluid flow supplied by the compressor 7 in step (i) can be divided between a flow directed towards the first exchanger 1, corresponding to step (ii), and a complementary flow circulating in the fourth bypass branch E.
The entire flow of refrigerant fluid from the first exchanger 1 then circulates in the third exchanger 3, as indicated in step (iii).
The flow of refrigerant fluid circulating in the fourth branch of bypass E joins the refrigerant fluid coming from the first exchanger 1 and circulates in the third exchanger 1.
The flow rate of refrigerant circulating in the fourth branch E can be zero. The flow rate of refrigerant circulating in the third exchanger 3 is therefore formed by the combination of the flow rate of refrigerant coming from the first exchanger 1 and the flow rate of refrigerant coming from the fourth branch E, the latter flow rate being able to be zero.
In steady state, this combination of the flow rate of refrigerant coming from the first exchanger 1 and the flow rate of refrigerant coming from the fourth branch of bypass E is equal to the flow rate circulating upstream of the division between a flow rate directed towards the first exchanger 1 and a complementary flow rate circulating in the fourth branch of bypass E, i.e. equal to the first flow rate Q1 supplied by the compressor 7.
After circulating in the third exchanger 3, the first flow Q1 is expanded to a low pressure state by the second expander 32, which corresponds to step (iv).
After this expansion, the low-pressure refrigerant circulates in the second exchanger 2, which corresponds to step (v).

The low-pressure refrigerant fluid from the second exchanger 2 reaches the compressor 7. The thermodynamic cycle is thus completed.
In other words, the method comprises, after step (v), a step: Circulating the refrigerant fluid coming from the second exchanger 2 towards an inlet 7a of the compressor 7.

According to the example of the FIG. 3 , the different stages of the process can be written:
(i) provide a first flow Q1 of high-pressure refrigerant fluid at the outlet of the compressor 7,
(ii) circulating the first flow Q1 of high-pressure refrigerant fluid in the first exchanger 1,
(iii) circulating the refrigerant fluid from the first exchanger 1 in the third exchanger 3,
(iv) circulating the refrigerant fluid from the third exchanger 3 in the second expansion valve 32 and carrying out an expansion to a low pressure lower than the high pressure,
(v) circulating in the second exchanger 2 the low-pressure refrigerant fluid coming from the second expansion valve 32.

According to the example of figures 4 and 5, the different stages of the process can be written:
(i) provide a first flow Q1 of high-pressure refrigerant fluid at the outlet of the compressor 7,
(i-1) dividing the first flow Q1 of high-pressure refrigerant into a first part circulating towards the first exchanger 1 and a second part circulating in the fourth bypass branch E,
(ii) circulating the first part of the first flow Q1 of high-pressure refrigerant fluid in the first exchanger 1,
(iii) circulating in the third exchanger 3 the refrigerant coming from the first exchanger 1 and the refrigerant coming from the fourth branch E,
(iv) circulating the refrigerant fluid from the third exchanger 3 in the second expansion valve 32 and carrying out an expansion to a low pressure lower than the high pressure,
(v) circulating in the second exchanger 2 the low-pressure refrigerant fluid coming from the second expansion valve 32.

The refrigerant flow rate in the first branch of bypass B is zero.
The third regulator 33 is in the closed position.

The flow rate of refrigerant fluid circulating in the second branch C between the fifth connection point 15 and the fourth connection point 14 is zero.
The sixth regulator 36 is thus in the closed position.

The flow rate of refrigerant circulating in the main loop A between the third connection point 13 and the sixth connection point 16 is zero.
The first regulator 31 is thus in the closed position.

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 the FIG. 2 .
The portions of the circuit 10 in which a flow of refrigerant fluid circulates are shown in thick continuous lines, while the portions in which the refrigerant fluid does not circulate are shown 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.

According to a first example of implementation of the proposed process, shown schematically on the FIG. 3 , the flow rate of refrigerant in the fourth branch of bypass E is zero.
The fifth regulator 35 is in this case in the closed position.

This operating mode can be used for example when the temperature of the element 25 of the traction chain is low, for example below 0°C. In this case, the refrigerant coming from the first exchanger 1 and having heated the interior air flow Fi is still sufficiently hot to heat the element 25 of the traction chain. In this operating mode in which the first exchanger 1 and the third exchanger 3 are connected in series on the refrigerant circuit 10, the thermodynamic coefficient of performance of the thermal conditioning system 100 is particularly advantageous. Indeed, the enthalpy of the refrigerant coming from the first exchanger 1 and having undergone expansion in the fourth expansion valve 34 is lowered by heating the element 25 of the traction chain. This results in an increase in the coefficient of performance.

In this operating mode, the refrigerant fluid discharged by the compressor 7 passes successively through the first connection point 11, the first stop valve 41, the seventh connection point 17, the first exchanger 1, the third connection point 13, the fourth expansion valve 34, the third exchanger 3, the fifth connection point 15, the second one-way valve 44, the sixth connection point 16, the second expansion valve 32, the second exchanger 2, the second connection point 12, the second stop valve 42, the tenth connection point 20, the fourth connection point 14, the accumulator 8, the second heat exchange section 6b of the internal exchanger 6, and reaches the low pressure inlet 7a of the compressor 7.

In this operating mode, the refrigerant flow rate is identical in the first exchanger 1, the third exchanger 3 and the second exchanger 2.

It is understood that the flow rates are identical, or equal, during steady-state operation of the thermal conditioning system 100.

According to a second and a third example of implementation of the proposed method, illustrated respectively on the FIG. 4 and on the FIG. 5 , the first flow Q1 of high-pressure refrigerant fluid is divided into a second flow Q2 circulating in the main loop A and a third flow Q3 circulating in the fourth bypass branch E.

In these operating modes, a portion of the high-pressure, high-temperature refrigerant can be directed toward the fourth branch E and joins the refrigerant coming from the first exchanger 1. The refrigerant flowing through the fourth branch E makes it possible to increase the thermal energy supplied to the element 25 of the electric traction chain and thus to increase the heating power supplied to this element 25. This type of operation can be implemented for example when the temperature of the element 25 of the traction chain is greater than or equal to the temperature of the refrigerant coming from the first exchanger 1. This refrigerant is then not able to heat the element 25 of the traction chain. The heating of this element 25 is then ensured by the refrigerant circulating in the fourth branch E.

In these operating modes, the flow rate of refrigerant in the first exchanger 1 is lower than the flow rate of refrigerant in the third exchanger 3.
The flow rate of refrigerant in the third exchanger 3 is identical to the flow rate of refrigerant in the second exchanger 2.
As before, we mean that the flow rates are equal during steady-state operation.

According to the third example of implementation of the method, illustrated in FIG. 5 , the second flow Q2 of refrigerant fluid passes through the fourth expansion valve 4 without undergoing expansion, and
the third flow Q3 of refrigerant fluid passes through the fifth expansion valve 35 without undergoing expansion.
The term "without undergoing any expansion" means not undergoing any reduction in pressure other than the inevitable pressure losses of a fluid circulating in a portion of the circuit.

For this, the fourth regulator 4 is in an opening position greater than a predetermined threshold.
The predetermined threshold is, for example, 80% of the maximum opening position of the fourth regulator 4.
Likewise, the fifth regulator 35 is in an opening position greater than a predetermined threshold, this threshold being for example 80% of the maximum opening position of the fifth regulator 4.

According to an example of implementation of the control process:
- the fourth regulator 34 is in the maximum opening position,
- the fifth regulator 35 is in the maximum opening position.

According to the operation illustrated on the FIG. 5 , the indoor airflow rate Fi may be zero.
For this purpose, the first motor-fan unit can be kept stationary. Alternatively or additionally, a movable flap, not shown in the figures, can be arranged in a position blocking the passage of air over the first exchanger 1.
In this case, there is no heat exchange in the first exchanger 1.
All the heating power is thus allocated to element 25 of the traction chain.

This operating mode allows element 25 of the drive train to be heated with high-pressure, high-temperature refrigerant.
In other words, the refrigerant circulating in the third exchanger 3 is at high pressure.

According to the implementation of the process illustrated in the FIG. 4 , the fourth expander 34 expands the second flow rate Q2 of refrigerant fluid to an intermediate pressure lower than the high pressure and higher than the low pressure, and the fifth expander 35 expands the third flow rate Q3 of refrigerant fluid to an intermediate pressure.

According to this operating case, the operation of the first exchanger 1 and that of the third exchanger 3 are decoupled. Indeed, the pressure of the refrigerant in the third exchanger 3 can be controlled independently of the pressure in the first exchanger 1. It is thus possible to independently adjust the temperature level in the two heat exchangers 1, 3. In addition, the distribution of the thermal power between the two exchangers 1, 3 can thus be adjusted on demand by controlling the respective openings of the fourth expansion valve 34 and the fifth expansion valve 35. The heating power supplied by the first exchanger 1 and the heating power supplied by the third exchanger 3 can thus be controlled independently of each other. In other words, the heating power supplied to the passenger compartment of the vehicle and the heating power supplied to the element 25 of the powertrain are controlled independently of each other.

The refrigerant circulating in the third exchanger 3 is at intermediate pressure. The value of the intermediate pressure is adjusted according to the temperature of element 25 of the traction chain.

The second flow Q2 of refrigerant fluid is expanded by passing through the fourth expansion valve 34 and passes to an intermediate pressure lower than the high pressure and higher than the low pressure, and
the third flow Q3 of refrigerant fluid is expanded by passing through the fifth expansion valve 35 and passes to an intermediate pressure.

The fourth regulator 34 is thus in the partially open position.
Likewise, the fifth regulator 35 is in the partially open position.
The opening position of the fourth regulator 34 may differ from the opening position of the fifth regulator 35. The opening position of the fourth regulator 34 and the opening position of the fifth regulator 35 are adjusted as a function of a thermal power to be supplied respectively by the first exchanger 1 and by the third exchanger 3.

The value of the so-called “high pressure” pressure, at the outlet of compressor 7, is for example between 80 bars and 120 bars.
The value of the so-called "intermediate" pressure, after expansion for example by the first regulator 31, is lower than the value of the high pressure. The intermediate pressure is for example between 25 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.

In the operating mode of the FIG. 4 and in that of the FIG. 5 , the flow of refrigerant fluid Q1 discharged by the compressor 7 passes successively through the first connection point 11, the first stop valve 41, and reaches the seventh connection point 17.
At the seventh connection point 17, the refrigerant fluid is divided between a second flow Q2 circulating in the main loop A towards the first exchanger 1, and a third flow Q3 circulating in the fourth bypass branch E towards the fifth expansion valve 35. The sum of the second flow Q2 and the third flow Q3 is equal to the first flow Q1.
The second flow Q2 circulating in the main loop A passes successively through the first exchanger 1, the third connection point 13, the fourth regulator 34, the eighth connection point 18.
The third flow Q3 circulating in the fourth branch of bypass E passes successively through the fifth regulator 35 and the eighth connection point 18, where it joins the second flow Q2 coming from the fourth regulator 34.
The two combined flows Q2 and Q3 pass through the third exchanger 3, the fifth connection point 15, the second one-way valve 44, the sixth connection point 16, the second expansion valve 32, the second exchanger 2, the second connection point 12, the second shut-off valve 42, the tenth connection point 20, the fourth connection point 14, the accumulator 8, the second heat exchange section 6b of the internal exchanger 6, and reach the low pressure inlet 7a of the compressor 7.
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.

According to the example illustrated in the various figures, 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 circulating in a heat transfer liquid circuit 40, the method comprises the steps:
- determine a temperature T3 of the heat transfer fluid at the outlet of the third exchanger 3.

The control process may include the step:
- controlling the first flow rate Q1 of refrigerant circulating in the refrigerant circuit 10 so as to control the temperature T3 of the heat transfer liquid at the outlet of the third exchanger 3 to a first target value.

The control process can thus include the following sub-steps:
- increase the flow rate Q1 of refrigerant circulating in the refrigerant circuit 10 if the temperature T3 of the heat transfer liquid at the outlet of the third exchanger 3 is lower than the first target value, and
- reduce the flow rate Q1 of refrigerant circulating in the refrigerant circuit 10 if the temperature T3 of the heat transfer liquid at the outlet of the third exchanger 3 is higher than the first target value.

The flow rate Q1 of refrigerant circulating in the refrigerant circuit 10 is equal to the flow rate of refrigerant discharged by the compressor 7.

The control process thus includes the sub-step:
- control the rotation speed of the compressor 7 in order to control the flow of refrigerant circulating in the refrigerant circuit 10.

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

The proposed method comprises a sub-step of determining the rotation speed of the compressor 7.
The control of the rotation speed of the compressor 7 is here achieved by controlling the electric current supplying the electric motor of the compressor 7, in order to increase or decrease the rotation speed.

An adjustment of the rotation speed of the compressor 7 thus makes it possible to adjust the temperature of the heat transfer liquid after the heat exchange undergone in the third exchanger 3.

The control process may include the steps:
- determine a value of the pressure P1 of the high-pressure refrigerant fluid,
- controlling an expansion of the refrigerant fluid in the second expansion valve 32 so as to control the pressure P1 of the refrigerant fluid 10 at high pressure to a second target value.

The process can thus include the following sub-steps:
- reducing a passage section of the refrigerant fluid through the second expansion valve 32 if the pressure P1 of the high-pressure refrigerant fluid 10 is greater than the second target value,
- increasing a passage section of the refrigerant fluid through the second expansion valve 32 if the pressure P1 of the high-pressure refrigerant fluid 10 is lower than the second target value.

The value of the pressure of the high-pressure refrigerant fluid can, for example, be determined at the outlet of the compressor 7.
The proposed method thus includes a sub-step:
- determine a pressure P1 of the refrigerant fluid at the outlet of compressor 7.

Alternatively, the value of the pressure of the high-pressure refrigerant fluid can be determined at the first exchanger 1.
The proposed method thus includes a sub-step:
- determine a pressure P1 of the refrigerant fluid in the first exchanger 1.

Control of the expansion of the refrigerant fluid in an expansion valve is achieved by controlling the flow section of the refrigerant fluid in the expansion valve.
By increasing the flow section of the refrigerant fluid, the expansion rate between upstream and downstream of the expansion valve decreases.
By reducing the flow section of the refrigerant fluid, the expansion rate between upstream and downstream of the expansion valve increases.

According to an exemplary implementation of the control method, the second target value depends on the first target value and a flow rate of heat transfer liquid in the third exchanger 3.

The process thus includes a sub-step:
- determine a flow rate of heat transfer fluid circulating in the heat transfer fluid circuit 40.

The target value of the high pressure P1 of the thermodynamic cycle thus depends on two independent parameters.
This second target value is determined for example by reading a two-dimensional map, i.e. dependent on two independent parameters. One of the input parameters of the map is the first target value of the temperature T3 of the heat transfer fluid at the outlet of the third exchanger 3.
The other input parameter of the mapping is the flow rate of heat transfer fluid in the third exchanger 3.
The flow rate of heat transfer liquid in the third exchanger 3 can for example be determined from the rotation speed of the pump of the circuit 40, or by a flow meter arranged on the circuit.

According to the implementation example illustrated in FIG. 3 , the control process includes the steps:
- determine a temperature T1 of the interior air flow Fi downstream of the first exchanger 1,
- controlling the first flow rate Q1 of refrigerant circulating in the refrigerant circuit 10 so as to control the temperature T1 of the interior air flow Fi downstream of the first exchanger 1 to a third target value.

An adjustment of the flow rate of high-pressure refrigerant delivered by the compressor 7 thus makes it possible to adjust the temperature level of the interior air flow Fi blown into the passenger compartment after having been heated at the level of the first exchanger 1, or of the exchanger 1A depending on the embodiment.
As before, this adjustment of the refrigerant flow rate is made by adjusting the rotation speed of the compressor 7.

According to this implementation example, the control method may include the steps:
- controlling an expansion of the refrigerant fluid in the fourth expansion valve 34 so as to control the temperature T3 of the heat transfer fluid at the outlet of the third exchanger 3 to a fourth target value.

The process can thus include the following sub-steps:
- reduce a passage section of the refrigerant fluid through the fourth expansion valve 34 if the temperature T3 of the heat transfer fluid at the outlet of the third exchanger 3 is higher than the fourth target value, and
- increase a passage section of the refrigerant fluid through the fourth expansion valve 34 if the temperature T3 of the heat transfer fluid at the outlet of the third exchanger 3 is lower than the fourth target value.

According to the implementation example illustrated in FIG. 4 , the process involves the following steps:
- determine a total thermal power PTot supplied jointly by the first exchanger 1 and by the third exchanger 3,
- controlling the first flow rate Q1 of refrigerant circulating in the refrigerant circuit 10 so as to control at a fifth target value the total thermal power Ptot supplied jointly by the first exchanger 1 and by the third exchanger 3.

The total thermal power Ptot supplied is equal to the sum of the thermal power supplied by the first exchanger 1 and the thermal power supplied by the third exchanger 3.
The thermal power supplied by the first exchanger 1 is determined from the flow rate of the indoor air flow Fi and the increase in temperature of the indoor air flow Fi when passing through the first exchanger 1.
In a similar manner, the thermal power supplied by the third exchanger 3 is determined from the flow rate of heat transfer liquid in the third exchanger 3 and the increase in temperature of the heat transfer liquid when passing through the third exchanger 3.

The control process can thus include the following sub-steps:
- increase the first flow rate Q1 of refrigerant circulating in the refrigerant circuit 10 if the total thermal power PTot supplied jointly by the first exchanger 1 and by the third exchanger 3 is less than the fifth target value, and
- reduce the first flow rate Q1 of refrigerant circulating in the refrigerant circuit 10 if the total thermal power PTot supplied jointly by the first exchanger 1 and by the third exchanger 3 is greater than the fifth target value.

According to the implementation example illustrated in FIG. 4 , the control process includes the steps:
- determine a temperature T1 of the interior air flow Fi downstream of the first exchanger 1,
- controlling an expansion of the refrigerant fluid in the fourth expansion valve 34 so as to control the temperature T1 of the interior air flow Fi downstream of the first exchanger 1 to a sixth target value.

According to the implementation example of the FIG. 4 , the control process may include the following sub-steps:
- 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 downstream of the first exchanger 1 is higher than the sixth target value,
- increase a passage section of the refrigerant fluid through the expansion valve 34 if the determined temperature T1 of the interior air flow Fi downstream of the first exchanger 1 is lower than the sixth target value.

According to the implementation example of the FIG. 4 , the control process may include the steps:
- controlling an expansion of the refrigerant fluid in the fifth expansion valve 35 so as to control the temperature T3 of the heat transfer fluid at the outlet of the third exchanger 3 to a seventh target value.

The control process can thus include the following sub-steps:
- reduce a passage section of the refrigerant fluid through the fifth expansion valve 35 if the determined temperature of the heat transfer fluid at the outlet of the third exchanger 3 is higher than the seventh target value,
- increase a passage section of the refrigerant fluid through the fifth expansion valve 35 if the determined temperature of the heat transfer fluid at the outlet of the third exchanger 3 is lower than the seventh target value.

According to yet another aspect of the example of the FIG. 4 , in which the refrigerant fluid circulating in the third exchanger 3 is in a subcritical state, the control method may comprise the steps:
- determine a sub-cooling Sc3 of the refrigerant fluid at the outlet of the third exchanger 3,
- controlling a passage section of the refrigerant fluid through the second expansion valve 32 so as to adjust the subcooling Sc3 of the refrigerant fluid at the outlet of the third exchanger 3 to an eighth target value.
In this case, the intermediate pressure is, for example, less than 65 bars.
A "subcritical" state is understood to mean a state in which the refrigerant is in a two-phase state, i.e. a mixture of liquid and vapor.

The subcooling Sc3 of the refrigerant fluid at the outlet of the third exchanger 3 is equal to the difference between:
- the saturation temperature Ts3 of the refrigerant, for a pressure equal to the pressure P3 of the refrigerant in the third exchanger 3, and
- the temperature TR3 of the refrigerant fluid at the outlet of the third exchanger 3.
Subcooling Sc3 is by definition positive, or zero.

The control process can thus include the following sub-steps:
- increasing a passage section of the refrigerant fluid through the second expansion valve 32 if the determined subcooling Sc3 of the refrigerant fluid at the outlet of the third exchanger 3 is greater than the eighth target value, and
- reduce a passage section of the refrigerant fluid through the second expansion valve 32 if the determined subcooling Sc3 of the refrigerant fluid at the outlet of the third exchanger 3 is less than the eighth target value.

According to the illustrated examples of implementation of the method, the fourth exchanger 4 does not participate in the heat exchanges. The seventh expansion valve 37 is in the closed position, and the fifth bypass branch F is not crossed by a flow of refrigerant fluid.
Likewise, the internal exchanger 6 does not participate in the heat exchanges, since the first heat exchange section 6a is not crossed by a flow of refrigerant fluid.

Claims (17)

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 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 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 process comprising the steps:
(i) providing a first flow (Q1) of high-pressure refrigerant fluid at the outlet of the compressor (7),
(ii) circulating at least part of the first flow (Q1) of high-pressure refrigerant fluid in the first exchanger (1),
(iii) circulating the refrigerant fluid from the first exchanger (1) in the third exchanger (3),
(iv) circulating the first flow (Q1) of refrigerant fluid in the second expansion valve (32) and expanding the first flow (Q1) to a low pressure lower than the high pressure,
(v) circulating the refrigerant at low pressure in the second exchanger (2). Method according to claim 1, in which the flow rate of refrigerant fluid in the fourth bypass branch (E) is zero. Method according to claim 1, in which the first flow (Q1) of high pressure refrigerant fluid is divided into a second flow (Q2) circulating in the main loop (A) and a third flow (Q3) circulating in the fourth bypass branch (E). Method according to claim 3, in which the second flow (Q2) of refrigerant fluid passes through the fourth expansion valve (4) without undergoing expansion, and
the third flow (Q3) of refrigerant fluid passes through the fifth expansion valve (35) without undergoing expansion. Method according to claim 3, in which the fourth expander (34) expands the second flow rate (Q2) of refrigerant fluid to an intermediate pressure lower than the high pressure and higher than the low pressure, and the fifth expander (35) expands the third flow rate (Q3) of refrigerant fluid to an intermediate pressure. Control method according to one of the preceding claims, in which the third heat exchanger (3) is thermally coupled with the element (25) of the electric powertrain of the vehicle by means of a heat transfer fluid circulating in a heat transfer fluid circuit (40), the method comprising the steps:
- determine a temperature (T3) of the heat transfer fluid at the outlet of the third exchanger (3),
- controlling the first flow rate (Q1) of refrigerant circulating in the refrigerant circuit (10) so as to control the temperature (T3) of the heat transfer liquid at the outlet of the third exchanger (3) to a first target value. Control method according to claim 2 or 4, comprising the steps:
- determine a value of the pressure (P1) of the high-pressure refrigerant,
- controlling an expansion of the refrigerant fluid in the second expansion valve (32) so as to control the pressure (P1) of the refrigerant fluid (10) at high pressure to a second target value. Control method according to the preceding claim, in which the second target value depends on the first target value and on a flow rate of heat transfer liquid in the third exchanger (3). Control method according to claim 4, in which:
- the fourth regulator (34) is in the maximum opening position,
- the fifth regulator (35) is in the maximum opening position. Control method according to claim 2, comprising the steps:
- determine a temperature (T1) of the interior air flow (Fi) downstream of the first exchanger (1),
- controlling the first flow rate (Q1) of refrigerant circulating in the refrigerant circuit (10) so as to control the temperature (T1) of the interior air flow (Fi) downstream of the first exchanger (1) to a third target value. Control method according to claim 2 or 10, comprising the steps:
- controlling an expansion of the refrigerant fluid in the fourth expansion valve (34) so as to control the temperature (T3) of the heat transfer fluid at the outlet of the third exchanger (3) to a fourth target value. Control method according to claim 3 or 5, comprising the steps:
- determine a total thermal power (PTot) supplied jointly by the first exchanger (1) and by the third exchanger (3),
- controlling the first flow rate (Q1) of refrigerant circulating in the refrigerant circuit (10) so as to control at a fifth target value the total thermal power (Ptot) supplied jointly by the first exchanger (1) and by the third exchanger (3). Control method according to one of claims 3, 5, or 12, comprising the steps:
- determine a temperature (T1) of the interior air flow (Fi) downstream of the first exchanger (1),
- controlling an expansion of the refrigerant fluid in the fourth expansion valve (34) so as to control the temperature (T1) of the interior air flow (Fi) downstream of the first exchanger (1) to a sixth target value. Control method according to one of claims 3, 5, 12 or 13, comprising the steps:
- controlling an expansion of the refrigerant fluid in the fifth expansion valve (35) so as to control the temperature (T3) of the heat transfer fluid at the outlet of the third exchanger (3) to a seventh target value. Control method according to claim 3 or 5 or according to one of claims 12 to 14, comprising the steps:
- determine a sub-cooling (Sc3) of the refrigerant fluid at the outlet of the third exchanger (3),
- - control a passage section of the refrigerant fluid through the second expansion valve (32) so as to adjust the subcooling (Sc3) of the refrigerant fluid at the outlet of the third exchanger (3) to an eighth target value. Thermal conditioning system (100) for a motor vehicle, comprising a refrigerant fluid circuit (10) comprising:
- a main loop (A) comprising successively, depending on the direction of circulation of the refrigerant fluid:
-- a compressor (7),
-- a first heat exchanger (1) thermally coupled with 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 pressure reducer (31) to a fourth connection point (14) arranged on the main loop (A) downstream of the second exchanger (2) and upstream of the accumulation device (8), the second branch branch (C) successively comprising a fourth pressure reducer (34) and a third heat exchanger (3) thermally coupled with an element (25) of an electric powertrain of a motor vehicle,
- a third branch branch (D) connecting a fifth connection point (15) arranged on the 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),
- an electronic control unit (63) 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). Computer program stored in a memory and configured to implement the method according to any one of claims 1 to 15.