FR3129628A1 - Motor vehicle ventilation system - Google Patents

Abstract

The invention relates to a ventilation system (3) for a motor vehicle comprising a hydraulic circuit for circulation of a heat transfer fluid, a first heat exchanger (5), a compressor, a second heat exchanger (6) configured as an evaporator when the system ventilation system (3) implemented in its first mode of operation (100), configured as a condenser when the ventilation system (3) is implemented in its second mode of operation (200), and an expansion valve. According to the invention, downstream of the second heat exchanger (6) according to the direction of the air flow in the ventilation system (3), the ventilation system (3) comprises a controlled device (12) for selectively directing the flow of air leaving the second heat exchanger (6) towards an interior (13) or towards an exterior of said passenger compartment (2). Figure to be published with abstract: Fig. 1

Description

Motor vehicle ventilation system

The technical context of the present invention is that of heating, cooling or ventilation devices. More particularly, the invention relates to a ventilation system for a motor vehicle.

It is known that the cooling of air intended to air-condition a passenger compartment of a motor vehicle by the passage of an air flow through a system comprising a first heat exchanger and a second heat exchanger. The first heat exchanger is placed at the inlet of a ventilation, heating and/or air conditioning installation, otherwise known as an HVAC installation, for the acronym "Heating, Ventilating and Air-Conditioning", while the second heat exchanger is placed at the outlet of said HVAC installation, relative to a flow of air passing through said HVAC installation.

Thus, in such an installation, the flow of air passing through the installation can be cooled or heated in order respectively to cool or heat a motor vehicle passenger compartment to which an outlet of the HVAC installation is connected.

In such an installation, the incoming air flow passes through the first heat exchanger which then operates a first heat transfer between the air flow and a refrigerant fluid circulating in the HVAC installation. Then, when the air flow reaches the outlet of the HVAC installation, it crosses the second heat exchanger which then operates a second heat transfer between the air flow and the refrigerant.

In known HVAC installations, each heat exchanger can operate:

- either in a so-called evaporator mode in which the heat exchanger tends to evaporate the refrigerant fluid circulating in the heat exchanger which, in contact with the air flow passing through the heat exchanger, absorbs its calories towards the flow of air in order to cool it; or, alternatively

- either in a so-called condenser mode in which the heat exchanger tends to condense the refrigerant fluid circulating in the heat exchanger which, in contact with the air flow passing through the heat exchanger, transfers its calories to the air flow to warm it up.

In a known manner, in such an HVAC installation, each heat exchanger is reversible and can operate in one or other of the modes described above. Furthermore, each heat exchanger of known HVAC installations works in a systematically different mode.

A disadvantage of such an HVAC installation is that, when the passenger compartment has been air-conditioned by a flow of air cooled by the HVAC installation and an occupant reverses the implementation of the HVAC installation in order to heat the passenger compartment, mist appears which can suddenly form on the windscreen and the windows of the passenger compartment. This phenomenon, known as “flash fogging” or “flash fogging”, is due to the presence of condensed water on the second heat exchanger of the HVAC installation when it was operating as an evaporator in order to cool the air flow. outgoing. Also, by reversing the air conditioning control to a heating control, the second heat exchanger then functions as a condenser. In doing so, it heats the flow of air passing through it, and it loads it with humidity by evaporating the water that has condensed on its walls. Thus, the flow of outgoing air, thus laden with humidity, is propelled towards the passenger compartment and condenses on the glass walls.

The formation of this mist impairs the good visibility of the driver, which we know is crucial for the safety of the occupants of the vehicle and their environment.

The object of the present invention is to provide a new ventilation system in order to at least largely solve the above problems and also to lead to other advantages.

Another object of the invention is to provide a ventilation system which reduces or prevents the appearance of fogging on the glass walls of the motor vehicle when the air conditioning control is reversed into a heating control.

Another object of the invention is to provide a ventilation system for a motor vehicle which is reliable in its operation.

Another object of the invention is to provide an inexpensive motor vehicle ventilation system, so as not to negatively impact the cost of the motor vehicle, which is intended to be economical.

Another object of the invention is to provide a motor vehicle ventilation system which is universal and configured to adapt to different motor vehicles.

According to a first aspect of the invention, at least one of the aforementioned objectives is achieved with a ventilation system for a motor vehicle, the ventilation system comprising: (i) a hydraulic circuit allowing circulation of a heat transfer fluid in said hydraulic circuit, the hydraulic circuit forming a closed loop; (ii) a first heat exchanger comprising a surface exchange zone between the heat transfer fluid circulating in the hydraulic circuit and an air flow entering the ventilation system, the first heat exchanger being configured to play the role of a condenser when the ventilation system is configured in its first mode of operation, and to act as an evaporator when the ventilation system is configured in its second mode of operation; (iii) a compressor configured to compress the heat transfer fluid circulating in the hydraulic circuit; (iv) a second heat exchanger comprising a surface exchange zone between the heat transfer fluid circulating in the hydraulic circuit and an air flow leaving the ventilation system, the second heat exchanger being configured to play the role of an evaporator when the ventilation system is configured in its first mode of operation, and to act as a condenser when the ventilation system is configured in its second mode of operation; (v) an expander configured to expand the heat transfer fluid circulating in the hydraulic circuit.

In the ventilation system according to the first aspect of the invention, downstream of the second heat exchanger according to the direction of the air flow in the ventilation system, the ventilation system comprises a controlled device for selectively directing the air flow leaving the second heat exchanger towards an interior of a passenger compartment of the motor vehicle or towards an exterior of said passenger compartment.

The ventilation system according to the first aspect of the invention is configured to alternately heat or cool the air flow. The air flow is heated or cooled upstream of an air distribution circuit supplying the passenger compartment of the vehicle.

In the ventilation system according to the first aspect of the invention, the hydraulic circuit is a closed circuit which allows the circulation of the heat transfer fluid in order to implement a thermodynamic cycle to transfer calories between the air flow passing through the ventilation and each heat exchanger of said ventilation system.

In the ventilation system according to the first aspect of the invention, the heat transfer fluid used is for example a subcritical fluid. Within the meaning of the invention, the heat transfer fluid can be in the liquid or gaseous state, depending on its state and its position in the hydraulic circuit.

In the ventilation system according to the first aspect of the invention, the compressor is a device for compressing heat transfer fluid. The compressor compresses and circulates the heat transfer fluid.

In the ventilation system according to the first aspect of the invention, the first heat exchanger is configured to carry out a heat exchange with the flow of air entering the ventilation system. When the invention is implemented, the air flow enters the ventilation system in front of the motor vehicle on which it is intended to be embarked.

In the first mode of operation of the ventilation system according to the first aspect of the invention, the first heat exchanger is implemented as a condenser and the second heat exchanger is implemented as an evaporator. Then, the flow of air taken at the level of the controlled device is a flow of cooled air.

In the second mode of operation of the ventilation system according to the first aspect of the invention, the first heat exchanger is implemented as an evaporator and the second heat exchanger is implemented as a condenser. Then, the air flow taken in at the level of the controlled device is a heated air flow.

In the ventilation system according to the first aspect of the invention, the second heat exchanger is configured to thermally treat the air flow intended to be directed by the controlled device.

Such a ventilation system, provided with a controlled device, makes it possible to deflect the flow of air, and in particular the flow of heated air, towards the outside of the passenger compartment. This deviation of the flow of air is advantageously implemented for a given time, the ventilation system also allowing a direction of the flow of heated air towards the passenger compartment. Thus, this solution makes it possible to preserve the passenger compartment from a “flash fogging” effect, and makes it possible to heat/cool a passenger compartment, while being simple to implement. The ventilation system according to the invention has the advantage of overcoming the drawbacks mentioned above, without having to make any significant modification to the motor vehicle that it equips.

The ventilation system in accordance with the first aspect of the invention advantageously comprises at least one of the improvements below, the technical characteristics forming these improvements being able to be taken alone or in combination:

- the controlled device comprises: (i) at least one first conduit in fluid communication with the ventilation system at the level of the second heat exchanger, the at least one first conduit opening into the passenger compartment; (ii) at least one second duct in fluid communication with the ventilation system at the level of the second heat exchanger, the at least one second duct opening outside the passenger compartment; (iii) a piloted valve configured to be able to assume any configuration between a first configuration in which the first conduit is closed and the second conduit is open and a second configuration in which the first conduit is open and the second conduit is closed. In the controlled device, the at least first conduit is intended to conduct the flow of air from the second heat exchanger to the passenger compartment. In the controlled device, the at least second conduit is intended to conduct the flow of air from the second heat exchanger to an environment outside the passenger compartment. In the piloted device, the piloted valve is intended to direct the flow of air towards the passenger compartment or towards the environment outside the passenger compartment. The controlled valve of the controlled device makes it possible to direct, towards the passenger compartment or in an environment outside the passenger compartment, the flow of air cooled by the second exchanger as an evaporator and the flow of air heated by the second exchanger as a condenser . Advantageously, to avoid "flash fogging", the controlled valve of the controlled device makes it possible to direct successively: (i) towards the passenger compartment the flow of air cooled by the second exchanger in evaporator, (ii) then in an external environment to the passenger compartment the air flow heated by the second condenser exchanger, (iii) and finally to the passenger compartment the air flow heated by the second condenser exchanger;

- the ventilation system in accordance with the first aspect of the invention is preferably controlled by a control method in accordance with a second aspect of the invention and as described below.

According to a second aspect of the invention, there is proposed a method for controlling a ventilation system in accordance with the first aspect of the invention or according to any one of its improvements, the ventilation system being configurable according to at least ( I) a first mode of operation in which the ventilation system cools air propelled into the passenger compartment of the motor vehicle, and (II) a second mode of operation in which the ventilation system heats the air propelled into said passenger compartment, the control method comprising the following steps: (i) a step of determining an enthalpy produced by the ventilation system in its first mode of operation to cool the air propelled into the passenger compartment; (ii) a step of calculating a quantity of water condensed on the second heat exchanger when the ventilation system is in its first mode of operation; (iii) a step of determining a heating time necessary to evaporate the condensed water on the second heat exchanger; (iv) a step of controlling the controlled device in order to direct the air propelled by the ventilation system outside the passenger compartment for the determined duration.

In the control method in accordance with the second aspect of the invention, the ventilation system can be implemented according to two alternative modes. The first operating mode makes it possible to cool the passenger compartment of the motor vehicle, and the second operating mode makes it possible to heat the passenger compartment of the motor vehicle. It is understood that the air propelled into the passenger compartment is an air flow directed by the controlled device of the ventilation system.

In the control method in accordance with the second aspect of the invention, the step of determining the enthalpy makes it possible to determine an enthalpy produced by the ventilation system in its first mode of operation. In other words, the determination step makes it possible to determine a quantity of energy produced by the ventilation system to cool the air propelled into the passenger compartment. Advantageously, the enthalpy is determined during the step of determining an enthalpy by numerical model.

In the control method in accordance with the second aspect of the invention, the calculation step makes it possible to calculate a quantity of condensed water on the second heat exchanger when the ventilation system is in its first mode of operation. It is understood that the quantity of water condensed on the second heat exchanger when the ventilation system is in its first mode of operation depends on the enthalpy produced by the ventilation system in its first mode of operation. Advantageously, the quantity of water condensed on the second heat exchanger is calculated during the calculation step by a numerical model of humid air based on the Mollier diagram. In particular, in the control method in accordance with the second aspect of the invention, the quantity of water condensed on the second heat exchanger can be calculated using simulation and/or modeling software. Such software makes it possible, for example, to calculate the properties of the air flow at the inlet of the second heat exchanger. Then, the enthalpy of airflow at condensation saturation is calculated. Then, an enthalpy balance makes it possible to calculate the energy necessary to start the condensation. The enthalpy balance is in the form of the following equation: Q = m_air * (H1-H2), where "Q" is the energy required for the condensation of water on the condenser, "m_air" is the flow mass of the air passing through the evaporator and “(H1-H2)” the enthalpy. If the energy changed with the heat transfer fluid exceeds the saturation energy of condensation, the water in the air stream begins to condense, then the relative humidity value remains 100%. Using the same enthalpy balance the outlet enthalpy of the air can be calculated. The mass of condensed water on the second heat exchanger is in the form of the following equation: M_cond = M(x_int-x_ext), where "M" is the mass of condensed water on the second heat exchanger, "x_int » the humidity of the air entering the second heat exchanger and « x_ext » the humidity of the air leaving the second heat exchanger. By reversing the method, the time required for the evaporation of the mass of condensed water can be calculated.

In the control method according to the second aspect of the invention, the step of determining a heating duration makes it possible to determine the heating duration necessary to evaporate the condensed water on the second heat exchanger. It is understood that as long as there is condensed water on the second heat exchanger, the air propelled into the passenger compartment is loaded with humidity and thus contributes to “flash fogging”. In the absence of condensed water on the second heat exchanger, in particular after evaporation of the latter, the propelled air becomes not loaded with humidity which helps to avoid "flash fogging". Advantageously, the heating duration is determined during the step of determining a heating duration by digital model.

In the piloting method in accordance with the second aspect of the invention, the piloting step makes it possible to pilot the piloted device in order to direct the air propelled by the ventilation system outside the passenger compartment for the determined duration. It is understood that at the end of the period determined during the determination step, the water which was condensed on the second heat exchanger is evaporated and the propelled air, not loaded with humidity, can be directed towards the cabin.

Such a control method, provided with a ventilation system with a controlled device, makes it possible to ensure a deflection of the flow of heated air towards the outside of the passenger compartment, for an optimal duration allowing the elimination of humidity in an environment outside the cabin. This deviation of the air flow is implemented for a determined period before the ventilation system allows the entry of the heated air flow to the passenger compartment. Thus, this solution makes it possible to preserve the passenger compartment from a “flash fogging” effect, and makes it possible to heat/cool a passenger compartment, while being simple to implement.

The control method in accordance with the second aspect of the invention advantageously comprises at least one of the improvements below, the technical characteristics forming these improvements being able to be taken alone or in combination:

- the enthalpy determination step is performed when the ventilation system is configured in its first operating mode. It is understood that it is when it is implemented in the first mode of operation that the ventilation system produces a given quantity of energy to cool the air propelled into the passenger compartment, said quantity of energy being determined during the determination step;

- the step of determining the heating duration is carried out when the ventilation system has switched from the first operating mode to the second operating mode. It is understood that, when the ventilation system is implemented in its first mode of operation and then in its second mode of operation, the effect of "flash fogging" is likely to occur. Also, the step of determining the duration of heating then contributes to avoiding it;

- the step of determining the heating duration is determined according to the calculated quantity of water and a heating power of the ventilation system. The heating time will be proportional to the calculated amount of water and inversely proportional to the heating power of the ventilation system. It is understood that the calculation of the heating time is done by considering the phenomenon of evaporation and assuming the existence of a mass of condensed water at the level of the second heat exchanger. This mass of condensed water is in a state of saturation compared to the wet diagram on a saturation curve. Knowing the heating power of the ventilation system transferred by the second heat exchanger in condenser mode, this power makes it possible to reach the enthalpy of evaporation. An evaporation temperature of this mass of water is for example calculated by a simulation and/or numerical modeling tool. The amount of heat is determined by the following formula: "Q = mcdT" where "Q" is the amount of heat; “c” is the known heat capacity of water; “dT” is the temperature difference between the water temperature and the evaporation temperature. The duration "t" is finally calculated using the equation "t = Q/Pth", where "Pth" is the power transferred by the condenser;

- the control process includes a preliminary step of determining a temperature and/or a humidity of air outside the passenger compartment. The determination step makes it possible to measure a temperature and/or a hygrometry of air outside the passenger compartment. Advantageously, a measurement is implemented by a sensor or a reading of information available on a communication network of the motor vehicle.

According to a third aspect of the invention, a motor vehicle is proposed comprising a ventilation system in accordance with the first aspect of the invention or according to any one of its improvements and a control unit configured to control the ventilation system in implementing the piloting method in accordance with the second aspect of the invention or according to any one of its improvements.

Various embodiments of the invention are provided, integrating according to all of their possible combinations the various optional characteristics set out here.

Other characteristics and advantages of the invention will become apparent through the description which follows on the one hand, and several embodiments given by way of indication and not limiting with reference to the appended diagrammatic drawings on the other hand, on which :

illustrates a schematic view of a motor vehicle according to the third aspect of the invention;

illustrates a schematic view of a ventilation system according to the first aspect of the invention;

illustrates by a flowchart a piloting method in accordance with the second aspect of the invention;

illustrates a psychrometric model making it possible to implement the process shown in .

Of course, the characteristics, the variants and the different embodiments of the invention can be associated with each other, according to various combinations, insofar as they are not incompatible or exclusive of each other. In particular, variants of the invention may be imagined comprising only a selection of characteristics described below in isolation from the other characteristics described, if this selection of characteristics is sufficient to confer a technical advantage or to differentiate the invention from to the state of the prior art.

In particular, all the variants and all the embodiments described can be combined with each other if nothing prevents this combination from a technical point of view.

In the figures, the elements common to several figures retain the same reference.

There shows a motor vehicle 1 according to the third aspect of the invention, seen from above. The motor vehicle 1 comprises a passenger compartment 2 and a ventilation system 3 as illustrated in and in accordance with the invention. In the , paths of an air flow circulating within the ventilation system 3 is indicated by different arrows 4.

In the , a first heat exchanger 5 of the ventilation system 3 and a second heat exchanger 6 of the ventilation system 3 are shown. In the motor vehicle 1, the ventilation system 3 is housed at the front of the motor vehicle 1, behind a front bumper 7 of the motor vehicle 1. Openings 8 allow the flow of air to enter when the motor vehicle 1 is in the rolling phase. The openings 8 are placed at the front of the motor vehicle 1, at the level of a front face 9 of the motor vehicle 1. The first heat exchanger 5 of the ventilation system 3 is downstream of the incoming air flow. The flow of air entering the motor vehicle 1 through the openings 8 and passing through the first heat exchanger 5 of the ventilation system 3 is shown in by first arrows 10.

There shows that, in accordance with the invention, downstream of the second heat exchanger 6 in the direction of the air flow in the ventilation system 3 represented by a second arrow 11, the ventilation system 3 comprises a controlled device 12. The device controlled 12 is configured to selectively direct the flow of air leaving the second heat exchanger 6, represented by the second arrow 11, alternately towards an interior 13 of the passenger compartment 2 of the motor vehicle 1 or towards an external environment 14 to said passenger compartment 2. In this case, the controlled device 12 comprises a first conduit 15 and a second conduit 16, both shown schematically to facilitate understanding of the invention. The first conduit 15 and the second conduit 16 are in fluid communication with the ventilation system 3 at the level of the second heat exchanger 6. The first conduit 15 opens into the passenger compartment 2 at the level of a first outlet 17. The second conduit 16 emerges outside the passenger compartment 2 at a second exit 18.

There shows that the piloted device 12 comprises a piloted valve 19. The piloted valve 19 is configured to be able to assume any configuration between a first configuration 24 in which the first conduit 15 is closed and the second conduit 16 is open, and a second configuration 25 in which the first conduit 15 is open and the second conduit 16 is closed. The first configuration 24 of the piloted valve 19 is represented by a first broken line 20 and the second configuration 25 of the piloted valve 19 is represented by a second broken line 21. In the first configuration 24, the air flow represented by a third arrow 22 is entirely blown into the environment 14 outside the passenger compartment 2. In the second configuration 25, the airflow represented by a fourth arrow 23 is completely blown into the passenger compartment 2.

It is understood that the flow of air directed by the controlled device 12 is advantageously heated or cooled by the second heat exchanger 6 upstream of said controlled device 12. The shows that the ventilation system 3 is configurable according to a first mode of operation 100 in which the ventilation system 3 cools propelled air represented by a first solid arrow 101, in the passenger compartment 2 of the motor vehicle 1, and a second mode of operation 200 in which the ventilation system 3 heats the propelled air, represented by a second solid arrow 201, in said passenger compartment 2. In the first mode of operation 100, the flow of air leaving the second heat exchanger 6 is cooled. In the second mode of operation 200, the flow of air leaving the second heat exchanger 6 is heated.

There shows that the motor vehicle 1 comprises a control unit 26 configured to control the ventilation system 3. The control unit 26 is connected, for example by means of an electric cable 27, to the controlled device 12 of the ventilation system 3 The control unit 26 makes it possible to implement a control method 300 in accordance with the second aspect of the invention described in .

There shows the ventilation system 3 according to the first aspect of the invention. The ventilation system 3 comprises a hydraulic circuit 28 which comprises a network of pipes 29 connecting components of the ventilation system 3, in this case the first heat exchanger 5, a compressor 30, the second heat exchanger 6, an expansion valve 31. In the embodiment illustrated in , the components of the ventilation system 3 are arranged in series.

It is understood that the hydraulic circuit 28 forms a closed circulation loop of a heat transfer fluid, not shown. The first heat exchanger 5 is configured to operate as a condenser when the second heat exchanger 6 operates as an evaporator, and vice versa. It is understood that the hydraulic circuit 28 may include a valve for reversing the direction of circulation of the heat transfer fluid, not shown, in order to reverse the direction of circulation of the heat transfer fluid according to the operating mode 100, 200 chosen. It is understood that such a reversal valve respects the one-way flow of the heat transfer fluid through the condenser.

There shows that the first heat exchanger 5 and the second heat exchanger 6 each comprise a surface exchange zone 32, 33 allowing the heat transfer fluid circulating in the hydraulic circuit 28 and the air flow passing through the heat exchanger 5, 6 considered, to perform a heat exchange.

There illustrates by a flowchart 301 the piloting method 300 in accordance with the second aspect of the invention. The piloting method 300 comprises a succession of steps. A step 320 for determining an enthalpy, a step 330 for calculating a quantity of condensed water, a step 340 for determining a heating time, a step 350 for controlling the controlled device 12. In this case , the control method 300 comprises a preliminary step 310 of determining a temperature and/or a humidity of an air outside the passenger compartment 2, preceding the step 320 of determining an enthalpy.

There shows that, in the control method 300 in which the step 320 of determining the enthalpy is carried out during the first operating mode 100 of the ventilation system 3 as represented by an arrow 302. The step of determining 340 the heating time is achieved when the ventilation system 3 has switched from the first operating mode 100 to the second operating mode 200, as represented by an arrow 303.

There illustrates a psychrometric model 400 making it possible to implement the method shown in . In the psychometric model 400 shown in , an abscissa axis 401 represents the dry bulb temperature (in °C), an ordinate axis 402 represents a humidity ratio (in g water/g dry air), enthalpy values 403 are located on oblique straight lines and wet bulb temperature 404 values are located on curves.

There represents a first point 410 corresponding to the state of the moist air flow at the inlet of the second evaporator. A second point 420 corresponds to the humidity saturation point of the air flow. Passing from the first point 410 to the second point 420, the humidity of the air flow condenses. A third point 430 corresponds to the state of the airflow after the enthalpy jump.

In summary, the invention relates to a ventilation system 3 for a motor vehicle 1, the ventilation system 3 comprising a hydraulic circuit 28 forming a closed circulation loop for a heat transfer fluid, a first heat exchanger 5 configured as a condenser when the system ventilation system 3 implemented in its first operating mode 100, configured as an evaporator when the ventilation system 3 is implemented in its second operating mode 200, a compressor 30, the second heat exchanger 6 configured as an evaporator when the system ventilation system 3 implemented in its first mode of operation 100 and configured as a condenser when the ventilation system 3 is implemented in its second mode of operation 200, and an expansion valve 31. In accordance with the invention, downstream of the second heat exchanger 6 according to the direction of the air flow in the ventilation system 3, the ventilation system 3 comprises a controlled device 12 to selectively direct the flow of air leaving the second heat exchanger 6 towards an interior 13 of a passenger compartment 2 of the motor vehicle 1 or to an exterior 14 of said passenger compartment 2.

Of course, the invention is not limited to the examples which have just been described and many adjustments can be made to these examples without departing from the scope of the invention. In particular, the different characteristics, forms, variants and embodiments of the invention may be associated with each other in various combinations insofar as they are not incompatible or exclusive of each other. In particular, all the variants and embodiments described above can be combined with each other.

Claims (8)

Ventilation system (3) for a motor vehicle (1), the ventilation system (3) comprising:
- a hydraulic circuit (28) allowing circulation of a heat transfer fluid in said hydraulic circuit (28), the hydraulic circuit (28) forming a closed loop;
- a first heat exchanger (5) comprising a surface exchange zone (32) between the heat transfer fluid circulating in the hydraulic circuit (28) and an air flow entering the ventilation system (3), the first heat exchanger (5) being configured to act as a condenser when the ventilation system (3) is configured in its first operating mode (100), and to act as an evaporator when the ventilation system (3) is configured in its second mode of operation (200);
- a compressor (30) configured to compress the heat transfer fluid circulating in the hydraulic circuit (28);
- a second heat exchanger (6) comprising a surface exchange zone (33) between the heat transfer fluid circulating in the hydraulic circuit (28) and a flow of air leaving the ventilation system (3), the second heat exchanger ( 6) being configured to play the role of an evaporator when the ventilation system (3) is configured in its first operating mode (100), and to play the role of a condenser when the ventilation system (3) is configured in its second mode of operation (200);
- an expansion valve (31) configured to expand the heat transfer fluid circulating in the hydraulic circuit (28);
characterized in that, downstream of the second heat exchanger (6) in the direction of the air flow in the ventilation system (3), the ventilation system (3) comprises a controlled device (12) for selectively directing the flow of air leaving the second heat exchanger (6) towards an interior (13) of a passenger compartment (2) of the motor vehicle (1) or towards an exterior (14) of said passenger compartment (2). Ventilation system (3) according to the preceding claim, in which the controlled device (12) comprises:
- at least one first conduit (15) in fluid communication with the ventilation system (3) at the level of the second heat exchanger (6), the at least one first conduit (15) opening into the passenger compartment (2);
- at least one second conduit (16) in fluid communication with the ventilation system (3) at the level of the second heat exchanger (6), the at least one second conduit (16) opening outside the passenger compartment (2) ;
- a piloted valve (19) configured to be able to take any configuration between a first configuration (24) in which the first conduit (15) is closed and the second conduit (16) is open and a second configuration (25) in which the first conduit (15) is open and the second conduit (16) is closed. Control method (300) of a ventilation system (3) according to any one of the preceding claims, the ventilation system (3) being configurable according to at least (i) a first operating mode (100) in which the ventilation system (3) cools an air propelled into the passenger compartment (2) of the motor vehicle (1), and (ii) a second mode of operation (200) in which the ventilation system (3) heats the air propelled in said cockpit (2), the piloting method (300) comprising the following steps:
- a step (320) of determining an enthalpy produced by the ventilation system (3) in its first operating mode (100) to cool the air propelled into the passenger compartment (2);
- a step (330) of calculating a quantity of water condensed on the second heat exchanger (6) when the ventilation system (3) is in its first operating mode (100);
- a step of determining (340) a heating time required to evaporate the condensed water on the second heat exchanger (6);
- a control step (350) of the controlled device (12) in order to direct the air propelled by the ventilation system (3) outside the passenger compartment (2) for the determined duration. Control method (300) according to claim 3, in which the step (320) of determining the enthalpy is carried out when the ventilation system (3) is configured in its first mode of operation (100). Control method (300) according to any one of claims 3 or 4, in which the step of determining (340) the duration of heating is carried out when the ventilation system (3) has switched from the first operating mode (100) to the second operating mode (200). Control method (300) according to any one of Claims 3 to 5, in which the step of determining (340) the duration of heating is determined according to the quantity of water calculated and a heating power the ventilation system (3). Piloting method (300) according to any one of claims 3 to 6, in which the piloting method (300) includes a preliminary step (310) of determining a temperature and/or a hygrometry of an air outside the passenger compartment (2). Motor vehicle (1) comprising a ventilation system (3) according to any one of claims 1 or 2 and a control unit (26) configured to control the ventilation system (3) by implementing the control method ( 300) according to any one of claims 3 to 7.