FR3129325A1 - Method for controlling the temperature of an air flow sent into a passenger compartment of a vehicle - Google Patents

Abstract

Method for controlling the temperature of an air flow sent into a passenger compartment of a vehicle Method for controlling the temperature of an air flow (28) in which a flap (304) allows at least partial entry of the recirculated air flow (302) in a ventilation, heating and/or air conditioning installation when at least the following conditions are met: i) the temperature of the fresh air flow (301) is below a threshold temperature, ii ) the temperature of the recirculated air flow (302) is higher than the temperature of the new air flow (301) plus a positive and non-zero threshold value and iii) the humidity level of the recirculated air flow (302) is below a threshold humidity level. (Figure 6)

Description

Method for controlling the temperature of an air flow sent into a passenger compartment of a vehicle

The field of the present invention is that of airflows traversing a vehicle, in particular a hybrid or electric motor vehicle. The present invention particularly deals with methods for controlling the temperature of such air flows occurring in a ventilation, heating and/or air conditioning installation.

Motor vehicles are commonly equipped with a refrigerant circuit used to heat or cool different areas or different components of the vehicle. It is in particular known to use these refrigerant circuits to cool an electrical storage device such as a battery of a vehicle equipped with this circuit.

It is also known to use this refrigerant circuit to thermally treat a flow of air sent to the passenger compartment of the vehicle. Such a heat treatment makes it possible to send hot air or cold air, according to the user's wishes, to respectively increase or decrease the temperature of the passenger compartment of the vehicle.

In another use of the refrigerant circuit, the air flow is intended to dehumidify the passenger compartment of the vehicle. “Dehumidifying” means the ability of the refrigerant circuit to limit the presence of water in the air in the vehicle passenger compartment. In fact, when humid air in the passenger compartment comes into contact with a cold surface, the water contained in the air condenses and a film of water droplets is deposited on the cold surfaces of the passenger compartment of the vehicle, especially on the windows. This film of water forms mist, in particular on the inside of the windscreen and the side windows of the vehicle, obstructing the driver's visibility of the road or his mirrors. This loss of visibility represents a significant risk for the safety of the occupants of the vehicle and in particular of collision with another vehicle.

It is known to use the refrigerant circuit to dry the flow of air sent into the passenger compartment of the vehicle. Thus, conventionally, a ventilation, heating and/or air conditioning installation, which will be designated in the rest of this description by the designation "installation", comprises a radiator and an evaporator which participate in the heat treatment of this air flow. The heat source of the radiator is in this case a constituent condenser of the refrigerant circuit. The condenser in combination with the radiator then form a hot spot in the refrigerant circuit which helps to increase the temperature of the air flow intended to be sent to the passenger compartment of the vehicle. The evaporator is a cold point in the refrigerant circuit, this evaporator helping to cool the air flow, and therefore to condense the humidity present in this air flow. This is how the risk of fogging is avoided while providing the thermal comfort required by the occupants of the vehicle.

It is also known that at low temperatures outside the vehicle cabin, the efficiency of the operation of the evaporator is impacted. For example, at outside temperatures close to 5°C, the evaporator presents a risk of obstruction which results from the fact that the water contained in the air freezes on contact with the evaporator, the latter having a surface temperature close to 0°C. This risk of obstruction of the evaporator limits the use of the latter and consequently the thermodynamic efficiency of the refrigerant circuit.

Indeed, when the temperature of the air flow entering the evaporator is low, the evaporator lowers the pressure within a low pressure part of the refrigerant circuit. This low pressure is a limiting factor in the thermodynamic cycle which prevents the production of sufficient calories on the condenser side, thus requiring the use of an additional heat source to reach the temperature desired by the occupants of the passenger compartment.

The present invention proposes to solve these various constraints by proposing a method for controlling the temperature of an air flow sent into a passenger compartment of a vehicle by a ventilation, heating and/or air conditioning installation which equips the vehicle during the implementation of a dehumidification mode of the air flow, the installation comprising a box inside which are installed a first heat exchanger configured to heat the air flow and a second heat exchanger configured to to cool the flow of air, the housing comprising at least one fresh air inlet to the passenger compartment, a recirculated air inlet and at least one shutter controlling a flow of fresh air entering the housing through the inlet of fresh air and a flow of recirculated air entering the housing via the recirculated air inlet, the installation comprising a first sensor determining the temperature of the flow of fresh air, means for determining a temperature of the flow of recirculated air and a means for determining a humidity of the recirculated air flow, method in which the flap allows at least partial entry of the recirculated air flow into the housing when the following conditions are met: i) the temperature of the fresh air flow is lower than a threshold temperature, ii) the temperature of the recirculated air flow is higher than the temperature of the fresh air flow plus a positive and non-zero threshold value and iii) the rate of humidity of the recirculated air flow is lower than a threshold humidity level.

The flow of air sent to the passenger compartment of a vehicle can meet several needs, one of them being that of dehumidifying the air inside the vehicle passenger compartment. The flow of air leaving the housing comes from a flow of new air, coming from outside the vehicle, and/or a flow of recirculated air, coming from inside the passenger compartment of the vehicle . Thus, the air flow leaving the housing is formed by the fresh air flow and/or the recirculated air flow entering the housing. The dehumidification of the air inside the passenger compartment of the vehicle is carried out by means of a ventilation, heating and/or air conditioning installation comprising at least two heat exchangers operating a heat exchange with the air flow. Depending on the configuration of the installation, the first heat exchanger, configured to heat the air flow, present in the installation, can be a heat exchanger, performing the function of condenser, placed in the casing and acting directly on the airflow temperature. This heat exchanger will also be designated in the following description by the term "condenser". The first heat exchanger can also be auxiliary equipment, such as a radiator, operating a heat exchange on the one hand with the condenser, by means of 'a fluid traversing the radiator and the condenser, and on the other hand, with the flow of air.

According to a characteristic of the invention, the flap prevents the entry of the recirculated air flow into the housing when at least one of the conditions is not fulfilled. The process acts on the position of this flap to modulate the source of the air flow. Thus, the shutter can be in a plurality of positions. When all the conditions are met, the flap is in a position allowing, at least partially or totally, the entry of the flow of recirculated air into the housing. When these conditions are not met, the flap is in a position preventing the recirculated air flow from entering the housing.

According to another characteristic of the invention, the ventilation, heating and/or air conditioning installation comprises a refrigerant fluid circuit equipping the vehicle which is traversed by at least one refrigerant fluid and which comprises at least one primary circuit and one secondary circuit , this primary circuit comprising at least one device for compressing the refrigerant fluid, a heat exchanger configured to operate a heat exchange between the refrigerant fluid and a fluid, acting on the temperature of the air flow and a third heat exchanger configured to operate a heat exchange between the refrigerant fluid and an external air flow, the secondary circuit comprising the second heat exchanger, the refrigerant circuit also comprising an expansion device upstream of the second heat exchanger and an expansion device upstream of the third heat exchanger, the secondary circuit being connected to the primary circuit in parallel with the third heat exchanger and the expansion element, a process in which the shutter allows at least partial entry of the recirculated air flow into the housing when the second heat exchanger and third heat exchanger are used as evaporators, while the first heat exchanger heats the airflow.

These heat exchangers are integrated into a refrigerant circuit. The refrigerant circuit comprises two circuit portions called the primary circuit and the secondary circuit. The primary circuit comprises a compression device, a heat exchanger, a third heat exchanger, an expansion element and a refrigerant fluid accumulation device. The secondary circuit comprises an expansion device, a closure means and a second heat exchanger. The housing of the ventilation, heating and/or air conditioning system comprises two heat exchangers, the first heat exchanger configured to heat the air flow and the second heat exchanger performing the function of evaporator. The temperature of the air flow entering the second heat exchanger modulates the efficiency of the thermodynamic cycle implemented in the refrigerant circuit. The control process makes it possible to improve the efficiency of this thermodynamic cycle by adapting the source of the air flow operating a heat exchange within the case. When the various conditions are met, the air flow entering the second heat exchanger comes at least in part from the recirculated air flow. This recirculated air flow is then warmer than the fresh air flow coming from outside the passenger compartment. The exchange of calories taking place between the second heat exchanger and the air flow is greater. As a result, the pressure of the refrigerant fluid in a low-pressure part of the refrigerant fluid circuit is higher than when this air flow comes from the fresh air flow.

According to one characteristic of the invention, the ventilation, heating and/or air conditioning installation comprises a refrigerant fluid circuit equipping the vehicle which is traversed by at least one refrigerant fluid and which comprises at least one primary circuit and one secondary circuit, this primary circuit comprising at least one device for compressing the refrigerant fluid, a heat exchanger configured to operate a heat exchange between the refrigerant fluid and a fluid, acting on the temperature of the air flow and a third heat exchanger configured to operate a heat exchange between the refrigerant fluid and the air flow outside the passenger compartment, the secondary circuit comprising a closure means, the second heat exchanger, the refrigerant fluid circuit also comprising an expansion device upstream of the second exchanger heat exchanger and an expansion element upstream of the third heat exchanger, the secondary circuit being connected to the primary circuit in parallel with the third heat exchanger and the expansion element, a process in which the shutter allows at least partial entry of the flow of air recirculated in the installation when the temperature of the fresh air flow is lower than 15°C +/- 2°C and when the expansion element is in a closed position preventing the passage of refrigerant fluid up to the third heat exchanger, the second heat exchanger being used as an evaporator, while the first heat exchanger heats the air flow.

According to an advantageous characteristic, the installation comprises a heat transfer liquid loop comprising at least one pump and traversing a radiator placed in the casing and configured to effect a heat exchange between the air flow and the heat transfer liquid, the heat exchanger being crossed by the heat transfer liquid so as to raise the temperature of the latter, the radiator being crossed by the heat transfer liquid so as to heat the air flow. This heat transfer liquid loop allows the heat exchanger to indirectly perform a heat exchange with the air flow.

According to another advantageous characteristic, the installation comprises the heat exchanger installed in the casing, the heat exchanger carrying out a heat exchange with the flow of air passing through the casing. In this configuration of the installation in which the first heat exchanger is the heat exchanger installed in the housing, the heat exchanger performs a direct heat exchange with the air flow. Thus, this configuration of the installation makes it possible to dispense with the use of a heat transfer liquid loop and a radiator.

According to one characteristic of the invention, the threshold temperature is equal to 15°C +/- 2°C.

According to another characteristic of the invention, the threshold temperature is equal to 10°C +/- 2°C.

According to another characteristic of the invention, the positive and non-zero threshold value is equal to 10°C.

According to one characteristic of the invention, the means for determining the temperature of the recirculated air flow is a temperature sensor.

According to another characteristic of the invention, the means for determining the humidity of the recirculated air flow is a humidity sensor.

According to one characteristic of the invention, the flap allows at least partial entry of the recirculated air flow into the housing as long as the temperature of the recirculated air flow is below a target temperature, the flap preventing the flow from entering of air recirculated into the enclosure when the temperature of the recirculated air stream is above the target temperature. The flap is in its position allowing the recirculated air flow to reach the housing when an additional condition is verified. In this additional condition, the flap is in its position allowing the recirculated air flow to reach the housing when the temperature of the recirculated air flow is below a target temperature. This target temperature is defined by the user(s) of the vehicle.

The invention also relates to a refrigerant circuit comprising at least one primary circuit and at least one secondary circuit, the primary circuit comprising at least one device for compressing the refrigerant fluid, a heat exchanger configured to effect a heat exchange between the refrigerant and a fluid, acting on the temperature of an air flow and a third heat exchanger configured to effect a heat exchange between the refrigerant fluid and an external air flow, the secondary circuit comprising a second heat exchanger, the refrigerant circuit also comprising an expansion member upstream of the second heat exchanger and an expansion member upstream of the third heat exchanger, the secondary circuit being connected to the primary circuit in parallel with the third heat exchanger and the expansion element, characterized in that the refrigerant circuit implements the method of controlling the temperature of an air flow.

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 :

is a schematic representation of a refrigerant circuit implementing the control method according to the invention.

is a schematic representation of a variant of the refrigerant circuit implementing the control method according to the invention, in which the heat exchanger is integrated into the installation.

is a schematic representation of the refrigerant fluid circuit in an operating mode ensuring cooling of the passenger compartment of the vehicle.

is a schematic representation of the refrigerant fluid circuit in an operating mode ensuring the heating of the passenger compartment of the vehicle.

is a diagrammatic representation of the refrigerant circuit in an operating mode ensuring the dehumidification of the passenger compartment of the vehicle.

is a schematic representation of a means of circulating an air flow sent to the passenger compartment of a vehicle.

is a flowchart presenting the different conditions implemented in the control process.

is a flowchart presenting the conditions implemented in the process for controlling the to which a fourth condition was added.

The terms upstream and downstream used in the following description refer to the direction of circulation of the fluid considered, i.e. the refrigerant fluid or the flow of recirculated or new or external air. The refrigerant fluid is symbolized by an arrow which illustrates the direction of circulation of the latter in the pipe considered. In FIGS. 3 to 5, the solid lines illustrate a circuit portion where the refrigerant fluid circulates, the broken lines illustrating a portion of the refrigerant fluid circuit where the refrigerant fluid does not circulate. In these figures, the open position of the valves is illustrated by a solid white filling and the closed position of these valves by a solid black filling.

There illustrates a refrigerant circuit 1 comprising a primary circuit 25, a secondary circuit 24 and a bypass branch 26 inside which a refrigerant fluid circulates. The secondary circuit 24, the primary circuit 25 and the bypass branch 26 are arranged such that the refrigerant circuit 1 is a closed circuit in which a thermodynamic cycle takes place.

The primary circuit 25 and the secondary circuit 24 separate at a point of divergence 14 and meet at a point of convergence 15 so that between the point of divergence 14 and the point of convergence 15, the secondary circuit 24 and the primary circuit 25 are mounted in parallel with respect to each other.

The primary circuit 25 will be described according to a direction of circulation of the refrigerant fluid in this primary circuit 25 from an outlet orifice 92 of a compression device 9 to an inlet orifice 91 of the compression device 9. The device compression 9 is, in the embodiment shown, an electric compressor with fixed displacement and variable speed. This compression device 9 is intended to compress the low-pressure refrigerant fluid entering through the inlet 91. This compression of the refrigerant fluid releases a high-pressure refrigerant fluid through the outlet orifice 92 of the compression device. Due to the principles of thermodynamics implemented in the refrigerant circuit 1, the passage of the refrigerant from the gaseous state, at the outlet of the compression device 9, to the liquid state at the outlet of a heat exchanger 2 generates heat. The volume of high-pressure refrigerant fluid at the outlet of the compression device 9 depends on the compression speed of this compression device 9. The higher the rotation speed of the compression device 9, the more the refrigerant circuit 1 will produce calories. Thus, it is possible to control the thermal power of the refrigerant circuit 1 by adapting the speed of rotation of this compression device 9.

The high-pressure refrigerant fluid leaving the compression device 9 circulates through the heat exchanger 2, which in the embodiment shown is a condenser. The heat exchanger 2 carries out a heat exchange with a fluid which, in the embodiment represented by the , is a heat transfer liquid circulating in a heat transfer liquid loop 200. The calories of the high pressure refrigerant fluid generated during the change of state of the refrigerant fluid are transmitted at the level of this heat exchanger 2, to the heat transfer liquid of the liquid loop heat carrier 200.

Thus, this heat transfer liquid transports the calories from the heat exchanger 2 to a radiator 8 located in the installation 20. The heat transfer liquid loop 200 comprises a first branch 21, by which the heat transfer fluid circulates from the heat exchanger 2 to the radiator 8, and a second branch 29 through which the heat transfer fluid circulates from the radiator 8 to the heat exchanger 2. This loop of heat transfer liquid 200 forms a closed loop in which a pump 22 ensures the circulation of the heat transfer liquid in this loop of heat transfer liquid 200.

The refrigerant, which has changed from a gaseous state to a liquid state, by condensation within the heat exchanger 2, passes through an accumulation device 4 which, in the embodiment shown, is a dehydrating bottle, comprising a desiccant element and an accumulator, intended to eliminate the humidity and fine particles present in the refrigerant fluid and acting as a fluid reservoir. It should be noted that this dehydrating bottle can advantageously be integrated into the heat exchanger 2.

At the outlet of the accumulation device 4, the refrigerant fluid reaches the point of divergence 14. At this point of divergence 14, the refrigerant fluid can join the secondary circuit 24 and/or reach an expansion element 12. This element of expansion 12 is located upstream of a third heat exchanger 13. This expansion element 12 can advantageously be electrically controlled and controlled electrically or electronically. Thus, the expansion element 12 is able to allow, in an open position, or to prevent, in a closed position, the passage of the refrigerant fluid to the third heat exchanger 13. This expansion element 12 is also able to take all intermediate positions to generate an expansion of the refrigerant fluid, that is to say to reduce the pressure of the refrigerant fluid. It should be noted that this expansion element 12 can be thermodynamically neutral, that is to say that the expansion element 12 can be an element of the refrigerant circuit 1 not involved in the thermodynamic cycle, in particular when this is at maximum opening and that it does not generate a loss of pressure.

The refrigerant fluid leaving the expansion element 12 enters the third heat exchanger 13 which, in the embodiment shown, is an evapo-condenser located on the front face of the vehicle. When the refrigerant fluid at the outlet of the expansion element 12 is at low pressure, that is to say when the expansion element 12 has generated an expansion of the high pressure refrigerant fluid, the third heat exchanger 13 behaves like an evaporator. When the refrigerant at the outlet of the expansion element 12 is at high pressure, that is to say when the expansion element 12 is thermodynamically neutral, the third heat exchanger 13 behaves like a condenser. It should be noted that the third heat exchanger 13 is crossed by a flow of air outside the passenger compartment 27 sent to the outside of the passenger compartment. This flow of air outside the passenger compartment 27 is intended to effect a heat exchange with the refrigerant fluid.

The refrigerant at the outlet of the third heat exchanger 13 reaches a first connection point 40, located downstream of the third heat exchanger 13, at which the bypass branch 26 is connected to the primary circuit 25.

This bypass branch 26 extends from the first connection point 40 to a second connection point 41 located on the secondary circuit 24. Thus, the bypass branch 26 allows the refrigerant fluid to pass from the primary circuit 25 to the secondary circuit 24. It should be noted that the bypass branch 26 comprises a non-return valve 10 preventing the refrigerant fluid from circulating from the secondary circuit 24 to the primary circuit 25 in certain operating modes.

On the primary circuit 25, downstream of the first connection point 40 is a first valve 11. This first valve 11 takes two positions, an open position and a closed position. In its open position, the first valve 11 allows the refrigerant fluid to borrow the primary circuit 25 beyond the connection point 40. In this open position of the first valve 11, the refrigerant fluid does not borrow the bypass branch 26 due to the pressure differential between the secondary circuit 24 and the primary circuit 25. In its closed position, the first valve 11 prevents the refrigerant from borrowing the primary circuit 25. The refrigerant then borrows the bypass branch 26 to join the secondary circuit 24. Advantageously, when the expansion element 12 generates an expansion of the refrigerant fluid, the first valve 11 is in its open position allowing the low pressure refrigerant fluid to reach the compression device 9 via the primary circuit 25. When the expansion element 12 is thermodynamically neutral, the refrigerant fluid at the outlet of the third heat exchanger 13 is at high pressure, the first valve 11 is then in its closed position and the refrigerant fluid borrows the bypass branch 26. It should be noted that this first valve 11 is advantageously electrically controlled and of the “all or nothing” type. Thus, when the expansion element 12 is thermodynamically neutral, the first valve 11 is in the closed position, while when the expansion element 12 generates an expansion of the refrigerant fluid, the first valve 11 is in its open position.

The low-pressure refrigerant fluid downstream of the first valve 11 reaches the point of convergence 15, at which the secondary circuit 24 and the primary circuit 25 meet. The refrigerant circuit comprises an internal heat exchanger 16 which makes it possible to exchanging calories between the low pressure refrigerant fluid and the high pressure refrigerant fluid. This heat transfer makes it possible to improve the performance of the thermodynamic cycle implemented in the refrigerant circuit 1. The primary circuit 25, downstream of the point of convergence 15 joins the compression device 9 and its inlet 91.

The secondary circuit 24 extends from the point of divergence 14 to the point of convergence 15 and comprises an expansion device 6, a second heat exchanger 7 and a closure means 5 which, in the embodiment shown, is a second valve 5a. The second valve 5a is located between the point of divergence 14 and the second connection point 41 and is advantageously electrically controlled and of the “all or nothing” type. The second valve 5a has two positions, an open position in which the second valve 5a allows the high-pressure refrigerant fluid to borrow the secondary circuit 24 and a closed position in which the second valve 5a prevents the high-pressure refrigerant fluid from borrowing the secondary circuit 24.

The expansion device 6, located downstream of the second valve 5a, between the second connection point 41 and the second heat exchanger 7, is a component of the secondary circuit 24 able to generate an expansion of the refrigerant fluid, it is that is to say to reduce the pressure of the refrigerant fluid. This expansion of the high-pressure refrigerant fluid contributes to the evaporation of the refrigerant fluid within the second heat exchanger 7. Due to the principles of thermodynamics implemented in the refrigerant circuit 1, the passage of the refrigerant fluid from the The liquid state, at the outlet of the heat exchanger 2, in the gaseous state at the outlet of the second heat exchanger 7 generates cold temperatures.

It should be noted that in an alternative embodiment of the invention, the expansion member 6 can be the closure means 5. In this case the closure means 5 ensures the expansion of the refrigerant fluid and modulates the passage refrigerant to the third heat exchanger 7.

The installation 20 comprises two heat exchangers, the first heat exchanger which, in the embodiment shown is the radiator 8, and the second heat exchanger 7 which, in the embodiment shown, is used as an evaporator. The first heat exchanger and the second heat exchanger 7 are traversed by the flow of air 28, coming from outside or inside the passenger compartment of the vehicle and going towards the passenger compartment of the vehicle. Thus, within this installation 20, a heat exchange takes place between the air flow 28 and on the one hand the second heat exchanger 7 and on the other hand the first heat exchanger. A temperature measuring device 17 installed in the air flow 28 at the outlet of the second heat exchanger 7 measures the temperature of the air flow 28. This data relating to the temperature of the air flow 28 is transmitted to a management device, such as a computer, to modulate the position of the second valve 5a. The low-pressure refrigerant fluid, at the outlet of the second heat exchanger 7, joins the primary circuit 25, at the level of the convergence point 15, upstream of the compression device 9.

Thus, the valves 11 and 5 control the refrigerant circuit to allow the refrigerant fluid to circulate between the primary circuit 25, the secondary circuit 24 and the bypass branch 26. This circulation of the refrigerant fluid allows the refrigerant circuit to ensure various functions, and in particular the functions of heating, cooling and dehumidifying the passenger compartment of the vehicle.

There illustrates a variant of the refrigerant circuit 1, in this variant the first heat exchanger is the heat exchanger 2 which is installed in the installation 20 and operates a heat exchange with a fluid which, in the embodiment shown, is the air flow 28. This variant of the refrigerant circuit 1 allows it to overcome the heat transfer liquid loop 200.

It should be noted that the element of the refrigerant circuit 1 present in the installation 20 and operating a heat exchange with the air flow 28 is the first heat exchanger. Thus, in the embodiment represented by the , the first heat exchanger is the radiator 8 whereas, in the embodiment represented by the , the first heat exchanger is heat exchanger 2.

There illustrates the refrigerant circuit 1 ensuring the refrigeration function of the passenger compartment of the vehicle. In this configuration of the refrigerant circuit 1, each of the first valve 11 and the second valve 5a are in their closed position. In this configuration of the refrigerant circuit 1, the refrigerant circulates in a direction of circulation of the refrigerant 30 in the primary circuit 25, the bypass branch 26 and the secondary circuit 24. In this configuration of the refrigerant circuit 1 represented over there , the expansion element 12 is thermodynamically neutral, that is to say wide open, and the third heat exchanger 13 is used as a condenser. The refrigerant undergoes a single expansion at the level of the expansion device 6. The air flow 28 performs a heat exchange with the second heat exchanger 7 so that the air flow 28 at the outlet of the installation 20 lowers the temperature of the vehicle interior relative to the temperature outside the vehicle interior.

There illustrates the refrigerant circuit 1 ensuring the function of heating the passenger compartment of the vehicle. In this configuration of the refrigerant circuit 1, the first valve 11 is in its open position, while the second valve 5a is in its closed position. The refrigerant fluid circulates in the primary circuit 25 and does not circulate in the secondary circuit 24 and in the bypass branch 26. This refrigerant fluid circulates in the refrigerant fluid circuit 1 according to a direction of circulation of the refrigerant fluid 30 going from the compression 9 to the third heat exchanger 13 and from this third heat exchanger 13 to the compression device 9. In this configuration of the second valve 5a, the refrigerant fluid does not reach the second heat exchanger 7, which, not supplied with refrigerant fluid, is thermally neutral. Within the installation 20, an exchange of calories takes place between the air flow 28 and the radiator 8 such that the air flow 28 is able to increase the temperature of the passenger compartment with respect to the outside cabin temperature.

There illustrates the refrigerant circuit 1 ensuring the dehumidification of the passenger compartment of the vehicle by overcoming the icing constraints of the second heat exchanger 7 and ensuring the heating of the air flow 28. In the configuration represented by the , the refrigerant circulates in parallel in the primary circuit 25 and in the secondary circuit 24. The first valve 11 of the primary circuit 25 is in its open position and the expansion element 12 generates an expansion of the high pressure refrigerant fluid coming from the heat exchanger 2.

In the embodiment shown, the dehumidification of the passenger compartment of the vehicle is carried out by sending a flow of air with a low humidity rate so as to dry the air inside the passenger compartment and a temperature ensuring the comfort of the passengers. occupants of the vehicle.

In this context, the refrigerant circuit 1 is able to provide such a function of dehumidifying the air inside the vehicle cabin. A suitable heat exchange takes place between the air flow 28 and, on the one hand, the second heat exchanger 7 and, on the other hand, the first heat exchanger in the installation 20. The heat exchange between the second heat exchanger heat 7 and the air flow 28 makes it possible to dry this air flow 28 while the heat exchange between the first heat exchanger and the air flow 28 makes it possible to increase the temperature of this flow of air 28. Indeed, the water contained in the air flow 28 condenses during the heat exchange between the air flow 28 and the second heat exchanger 7, thus at the outlet of this second heat exchanger 7 the air flow 28 is dry and cold. However, when the temperature outside the passenger compartment is significantly lower than 20° C., this air flow 28 must be heated to ensure the comfort of the occupants of the vehicle. For this purpose, the air flow 28 operates an exchange of calories with the first heat exchanger so that at the outlet of the installation 20, the air flow 28 is dry and hot.

There illustrates a means of circulation of the air flow 28 to the second heat exchanger 7. This is for example a recirculated and/or new air inlet box. This air flow circulation means 28 is, in the embodiment shown, a pipe portion 300 in which the air flow 28 is formed in a mixing chamber 309 and passes to the second heat exchanger 7 Into this mixing chamber 309 emerge an inlet for a fresh air flow 308 via which the fresh air flow arrives 301 and an inlet for a recirculated air flow 306 via which the recirculated air flow arrives. 302. The fresh air flow 301 is an air flow coming from outside the vehicle while the recirculated air flow 302 is an air flow coming from inside the passenger compartment of the vehicle.

The access of the new and recirculated air flows 301 and 302 into the mixing chamber 309 is controlled by an actuator 303. This actuator 303 comprises a connecting member 307 and a movable element which, in the embodiment represented, is a flap 304. In the embodiment represented by the , the actuator 303 can have a plurality of positions. Indeed, the flap 304 has two positions, a first position 3040 in which the flap 304 prevents the flow of fresh air 301 from reaching the mixing chamber 309, then the second heat exchanger 7. It should be noted that in this first position 3040 of the flap 304, only the flow of recirculated air 302 can reach the mixing chamber 309. The flap 304 also has a second position 3041 in which the flap 304 prevents the flow of recirculated air 302 from reaching the mixing chamber 309. It should be noted that in this second position 3041 of the shutter 304, only the fresh air flow 301 can reach the mixing chamber 309 and the second heat exchanger 7. The shutter 304 can also take a plurality of positions between the first position 3040 and the second position 3041 such that the flap 304 is capable of at least partially allowing the recirculated air flow 301 to reach the mixing chamber 309, then the installation 20. The flow of air 28 comes from the fresh air flow 301 and/or from the recirculated air flow 302, depending on the position of the flap 304.

The air flow circulation means 28 also comprises a first temperature sensor 3010 capable of measuring the temperature of the fresh air flow 301 and a means for determining a temperature of the recirculated air flow 302 which, in the mode embodiment shown, is a second temperature sensor 3020 capable of measuring the temperature of the recirculated air flow 302. It should be noted that in the embodiment shown, the first and second temperature sensor are placed in the duct portion 300. Nevertheless, these temperature sensors can be located at any other position on the vehicle as long as these sensors are capable of measuring the flow of recirculated air 302 and the flow of fresh air 301. Thus, the first temperature sensor 3010 can, for example, be located in a rear-view mirror of the vehicle and the second temperature sensor 3020 can, for example, be located on a dashboard of the passenger compartment of the vehicle.

There is a flowchart which illustrates the conditions for implementing the control method. This control method makes it possible to modulate the opening of the flap 304 so that the air flow 28 can come from the recirculated air flow 302 and/or from the fresh air flow 301.

The control method according to the invention authorizes the flow of recirculated air 302 to reach the installation 20 if at least three conditions 500, 503 and 504 are met. It should be noted that when at least one of the three conditions is not verified, the flap 304 is in its second position 3041 in which the flap 304 prevents the flow of recirculated air 302 from reaching the installation 20 This configuration of the flap 304 in which the recirculated air flow 302 cannot reach the installation 20 is represented in FIGS. 7 and 8 by the step 502. It should be noted that as long as at least one of the conditions 500, 503 and 504 is not checked, the shutter 304 is in its second position 3041.

In the first condition 500, the method implemented evaluates the temperature of the fresh air flow 301, this information relating to the temperature of the fresh air flow 301 being able to be obtained by means of the first temperature sensor 3010 located at the level of the fresh air flow inlet 308 through which the fresh air flow 301 passes, or even via a temperature sensor placed outside the vehicle. If the outside temperature is below a threshold temperature, substantially equal to 15° C., then the first condition 500 is verified. If the temperature is above this threshold temperature, then the first condition is not verified and the control method implements step 502 in which the air flow 28 comes from the fresh air flow 301.

In the second condition 503, the control method verifies that the temperature of the recirculated air flow 302 is higher than the temperature of the fresh air flow 301 plus a threshold value, for example 10°C. This information relating to the temperature of the recirculated air flow 302 can be obtained by means of the second temperature sensor 3020 located at the inlet of the recirculated air flow 306 through which passes the recirculated air flow 302 or even placed in the passenger compartment of the vehicle. If the temperature of the recirculated air flow 302 is greater than the temperature of the fresh air flow 301 plus a threshold value then the second condition 503 is verified. If the temperature of the passenger compartment is lower than the temperature outside the passenger compartment of the vehicle, then the second condition 503 is not verified and the control method implements the step 502 in which the air flow 28 comes from fresh air flow 301.

The third condition 504 verifies that the humidity level of the passenger compartment of the vehicle does not exceed a threshold humidity level. This information relating to the percentage of humidity present in the interior air of the passenger compartment is obtained by a means for determining a humidity of the recirculated flow 302 which can, for example, be a humidity sensor placed in the passenger compartment. of the vehicle or even a humidity sensor placed in the driving portion 300. If the humidity content of the passenger compartment of the vehicle is lower than the threshold humidity level, then the third condition 504 is verified and the control method puts implements a step 505 in which the flap 304 is in its first position 3040, the air flow 28 coming from the recirculated air flow 302. It should be noted that when the method implements the step 505, the flap 304 can be in a plurality of positions when the air flow 28 can come at least in part from the recirculated air flow 302. If the humidity content of the vehicle interior is higher than the rate of threshold humidity, then the third condition 503 is not verified and the control method implements step 502 in which the air flow 28 comes from the fresh air flow 301, the flap 304 being in its second position 3041, as long as the conditions are not met.

It should be noted that each of these three conditions can be checked in a different order or simultaneously. As soon as each condition is verified, the air flow 28 comes at least in part, or even entirely, from the recirculated air flow 302, the flap 304 being in a position located between its first position 3040 inclusive and its second position 3041 excluded.

There is a flowchart which illustrates the conditions for implementing the control method as represented by the to which is added a fourth condition 501. This fourth condition 501 of the control method is verified as long as the temperature of the recirculated air flow 302 is below a target temperature. This target temperature is defined by the occupant(s) of the vehicle. As soon as the temperature of the recirculated air flow 301 is higher than this target temperature, the control method implements step 502 in which the flap 304 is in its second position 3041. If the target temperature, chosen by the passengers of the vehicle, has not been reached, then the control method implements a step 505 in which the air flow 28 comes at least in part from the recirculated air flow 302, the flap 304 being in a position located between its first position 3040 and its second position 3041.

The temperature of the air flow 28 leaving the mixing chamber 309 when all the conditions are met is higher than the temperature of the air flow 28 leaving the mixing chamber when at least one condition is not met. . The method according to the invention thus makes it possible to increase the exchange of calories between the air flow 28 and the second heat exchanger 7 and to evacuate more heat on the heat exchanger 2. As a result, the pressure in the low pressure part of the refrigerant circuit 1 is greater when the conditions 500, 501, 503 and 504 are fulfilled and the air flow 28 comes at least in part from the recirculated air flow 302 than when, in similar temperature and humidity conditions, the air flow 28 comes from the fresh air flow 301.

The invention, as it has just been described, achieves the goal it has set itself, and makes it possible to propose a method for controlling the temperature of a flow of air sent to the passenger compartment of a vehicle making it possible to improve the ability of the refrigerant circuit to generate an air flow capable of dissipating fog from a vehicle, limits the energy consumption of the circuit and in particular by limiting the use of auxiliary devices for ensure the generation of such an air flow. Variants not described here could be implemented without departing from the context of the invention, since, in accordance with the invention, they include a method for controlling the temperature of an air flow in accordance with the invention. .

Claims (13)

Method for controlling the temperature of a flow of air (28) sent into a passenger compartment of a vehicle by a ventilation, heating and/or air conditioning installation (20) which equips the vehicle during the implementation of a dehumidification mode of said air flow (28), the installation (20) comprising a box inside which are installed a first heat exchanger configured to heat the air flow (28) and a second heat (7) configured to cool the air flow (28), the housing comprising at least one fresh air flow inlet (308), one recirculated air flow inlet (306) and at least one at least one flap (304) controlling a fresh airflow (301) entering the housing through the fresh airflow inlet (308) and a recirculated airflow (302) entering the housing through the inlet of the recirculated air flow (306), the installation (20) comprising a first temperature sensor (3010) determining the temperature of the fresh air flow (301), means for determining a temperature of the flow of recirculated air (302) and a means for determining a humidity of the recirculated air flow (302), method in which the flap (304) allows at least partial entry of the recirculated air flow (302) into the housing when at least the following conditions are met: i) the temperature of the fresh air flow (301) is lower than a threshold temperature, ii) the temperature of the recirculated air flow (302) is higher than the temperature of the flow of fresh air (301) plus a positive and non-zero threshold value and iii) the humidity level of the recirculated air flow (302) is lower than a threshold humidity level. Method for controlling the temperature of an air flow (28) according to the preceding claim, characterized in that the shutter (304) prevents the entry of the interior air flow (302) into the housing when at least one of the conditions (i, ii, iii) is not met Method for controlling the temperature of an air flow (28) according to any one of the preceding claims, characterized in that the threshold temperature is equal to 10°C +/- 2°C. Method for controlling the temperature of an air flow (28) according to the preceding claim, in which the ventilation, heating and/or air conditioning installation (20) comprises a refrigerant circuit (1) fitted to the vehicle which is through which at least one refrigerant fluid flows and which comprises at least one primary circuit (25) and one secondary circuit (24), this primary circuit (25) comprising at least one refrigerant fluid compression device (9), a heat exchanger ( 2) configured to operate a heat exchange between the refrigerant fluid and a fluid, acting on the temperature of the air flow (28) and a third heat exchanger (13) configured to operate a heat exchange between the refrigerant fluid and the flow air outside the passenger compartment (27), the secondary circuit (24) comprising the second heat exchanger (7), the refrigerant circuit (1) also comprising an expansion device (6) upstream of the second heat exchanger (7) and an expansion element (12) upstream of the third heat exchanger (13), the secondary circuit (24) being connected to the primary circuit (25) in parallel with the third heat exchanger (13) and the expansion element (12), a method in which the flap (304) allows at least partial entry of the recirculated air flow (302) into the installation (20) when the temperature of the fresh air flow (301) is lower than 10°C +/- 2°C and when the second heat exchanger (7) and the third heat exchanger (13) are used as evaporators, while the first heat exchanger heats the air flow ( 28). Method for controlling the temperature of an air flow (28) according to Claims 1 and 2, characterized in that the threshold temperature is equal to 15°C +/- 2°C. Method for controlling the temperature of an air flow (28) according to the preceding claim, in which the ventilation, heating and/or air conditioning installation (20) comprises a refrigerant circuit (1) fitted to the vehicle which is through which at least one refrigerant fluid flows and which comprises at least one primary circuit (25) and one secondary circuit (24), this primary circuit (25) comprising at least one refrigerant fluid compression device (9), a heat exchanger ( 2) configured to operate a heat exchange between the refrigerant fluid and a fluid, acting on the temperature of the air flow (28) and a third heat exchanger (13) configured to operate a heat exchange between the refrigerant fluid and the flow air from outside the passenger compartment (27), the secondary circuit (24) comprising a closure means (5), the second heat exchanger (7), the refrigerant circuit (1) also comprising a expansion (6) upstream of the second heat exchanger (7) and an expansion element (12) upstream of the third heat exchanger (13), the secondary circuit (24) being connected to the primary circuit (25) in parallel with the third heat exchanger (13) and the expansion element (12), a method in which the flap (304) allows at least partial entry of the recirculated air flow (302) into the installation (20) when the temperature of the fresh air flow (301) is less than 15°C +/- 2°C and when the expansion element (12) is in a closed position preventing the passage of the refrigerant fluid to the third heat exchanger ( 13), the second heat exchanger (7) being used as an evaporator, while the first heat exchanger heats the air flow (28). Method for controlling the temperature of an air flow (28) according to any one of the preceding claims, characterized in that the means for determining the temperature of the recirculated air flow (302) is a sensor (3020) . Method of controlling the temperature of an air flow (28) according to any one of the preceding claims, characterized in that the means for determining the humidity of the recirculated air flow (302) is a sensor of humidity. A method of controlling the temperature of an air flow (28) according to any one of the preceding claims, in combination with claim 4 or 6, in which the installation (20) comprises a heat transfer liquid loop (200 ) comprising at least one pump (22) and traversing a radiator (8) placed in the casing and configured to effect a heat exchange between the air flow (28) and the heat transfer liquid, the heat exchanger (2) being through which the heat transfer liquid passes so as to raise the temperature of the latter, the radiator (8) being passed through by the heat transfer liquid so as to heat the air flow (28). Method for controlling the temperature of an air flow (28) according to any one of Claims 1 to 3, characterized in that the installation (20) comprises the heat exchanger (2) installed in the housing, a heat exchanger (2) operating a heat exchange with the air flow (28) passing through the housing. Method for controlling the temperature of an air flow (28) according to any one of the preceding claims, characterized in that the positive and non-zero threshold value is equal to 10°C Method for controlling the temperature of an air flow (28) according to any one of the preceding claims, characterized in that the flap (304) allows at least partial entry of the recirculated air flow (302) into the housing as long as the temperature of the recirculated air flow (302) is below a target temperature, the shutter (304) preventing the entry of the recirculated air flow (302) into the housing when the temperature of the flow of recirculated air (302) is above the target temperature. Refrigerant circuit (1) comprising at least one primary circuit (25) and at least one secondary circuit (24), the primary circuit (25) comprising at least one device (9) for compressing the refrigerant fluid, a heat exchanger ( 2) configured to operate a heat exchange between the refrigerant fluid and a fluid, acting on the temperature of an air flow (28) and a third heat exchanger (13) configured to operate a heat exchange between the refrigerant fluid and an external air flow (27), the secondary circuit (24) comprising a second heat exchanger (7), the refrigerant circuit (1) also comprising an expansion device (6) upstream of the second heat exchanger (7) and an expansion element (12) upstream of the third heat exchanger (13), the secondary circuit (24) being connected to the primary circuit (25) in parallel with the third heat exchanger (13) and the expansion element (12), characterized in that the refrigerant circuit (1) implements the method for controlling the temperature of an air flow (28) according to any one of the preceding claims,