FR3129326A1 - Process for dehumidifying a passenger compartment of a vehicle - Google Patents

Abstract

Process for dehumidifying the passenger compartment of a vehicle. The present invention relates to a dehumidification method implementing a refrigerant fluid circuit (1) for a vehicle, characterized in that the dehumidification method implements: - at least a first step in which, at a temperature of a flow interior air (28) at the outlet of a third heat exchanger (7) above a first temperature, a closure means (5) is placed in an open position, - at least a second step in which, at a temperature of the interior air flow (28) leaving the third heat exchanger (7) lower than a second temperature, the closure means (5) is placed in a closed position, the second temperature being lower than the first temperature. (Figure 1)

Description

Process for dehumidifying a passenger compartment of a vehicle

The field of the present invention is that of refrigerant fluid circuits for vehicles, in particular for hybrid or electric motor vehicles. The present invention particularly deals with dehumidification methods implementing such refrigerant circuits.

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 heating, ventilation and air conditioning installation, which will be designated in the remainder 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 radiator is then a hot spot in the coolant 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 its use.

Furthermore, when the temperature of the air flow at the inlet of the evaporator is low, in particular when this temperature is below 12° C., 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 means of a method for dehumidifying a passenger compartment of a vehicle through which a refrigerant fluid passes and comprising at least one primary circuit and one secondary circuit, the primary circuit comprising at least one device compression of the refrigerant fluid, a first heat exchanger configured to operate a heat exchange between the refrigerant fluid and a fluid, an expansion element and a second heat exchanger configured to operate a heat exchange between the refrigerant fluid and a flow of air outside the passenger compartment of the vehicle, the secondary circuit being connected to the primary circuit in parallel with the second heat exchanger and the expansion element and comprising an expansion member and a third heat exchanger configured to effect a heat exchange between the refrigerant fluid and an interior air flow sent into the passenger compartment of the vehicle, the secondary circuit comprising at least one closure means able to adopt a closed position in which the circulation of the refrigerant fluid is prevented within the secondary circuit and an open position allowing the circulation of the refrigerant fluid within the secondary circuit, the primary circuit and the secondary circuit are traversed simultaneously by the refrigerant fluid, method of dehumidifying a passenger compartment of a vehicle during which the expansion element and the expansion member operates an expansion and where the second heat exchanger and the third heat exchanger ensure the evaporation of the refrigerant characterized in that, at an air temperature outside the vehicle below a first threshold, the process dehumidification implements:

- at least a first step in which, at a temperature of the internal air flow at the outlet of the third heat exchanger greater than a first temperature, the closure means is placed in its open position,

- at least a second step in which, at a temperature of the internal air flow at the outlet of the third heat exchanger lower than a second temperature, the closure means is placed in its closed position, the second temperature being lower than the first temperature.

The refrigerant circuit for a vehicle comprises two portions of circuits called the primary circuit and the secondary circuit. The primary circuit comprises a compression device, a first heat exchanger, an expansion element, a second heat exchanger and a refrigerant fluid accumulation device. The secondary circuit comprises an expansion device, a closure means and a third heat exchanger. The refrigerant circuit is configured so that this secondary circuit can be isolated from the rest of the circuit. This isolation of the secondary circuit is possible by means of closure which can take two positions, an open position and a closed position. In its open position, the closure means allows the refrigerant fluid to circulate in the secondary circuit, and more particularly to reach the third heat exchanger. In the closed position of the closure means, the refrigerant does not circulate in the secondary circuit which is isolated from the rest of the refrigerant circuit. The open or closed position of the closure means depends on the temperature of the interior air flow at the outlet of the third heat exchanger. This data relating to the temperature of the interior air flow at the outlet of the third heat exchanger is provided, for example, by a sensor located at the level of the interior air flow, at the outlet of the third heat exchanger. By way of example, when the temperature of the outside air is, for example, less than 12° C., advantageously less than 7° C., advantageously between 5° C. and 7° C., the method implements the first and the second step. During the implementation of these steps, when the temperature of the interior air flow at the outlet of the third heat exchanger is greater than or equal to, for example 7° C., the closure means is in its open position while when the temperature of the interior air flow at the outlet of this third heat exchanger is less than or equal to, for example 3° C., the closure means is in its closed position. The temperature of the interior air flow at the outlet of the third heat exchanger fluctuates between 3°C and 7°C to tend, in this example, towards an average temperature of 5°C. The position of the obturation means forms a cycle of openings and closings of the obturation means. It should be noted on the one hand, that the temperature towards which the interior air flow at the outlet of the third heat exchanger tends depends on the temperature range at which the interior air flow at the outlet of the third heat exchanger oscillates. and on the other hand, that the closure means remains in its open or closed position in which it is located until reaching the first temperature or the second temperature depending on the position of the closure means. According to another example, when the flow of outside air is at 5° C., the closure means will be in its closed position at 3° C. and in its open position at 3.8° C.

According to a feature of the invention, the first heat exchanger raises the temperature of the interior air flow. It is understood that the first heat exchanger acts on the temperature of the air flow by transmitting calories to the interior air flow. This exchange of calories can take place directly between the first heat exchanger and the interior air flow sent to the passenger compartment of the vehicle. This exchange of calories can also take place indirectly, in this case, an auxiliary equipment, such as a radiator, operates an exchange of calories with the first heat exchanger, by means of a fluid flowing through the radiator and the first exchanger of heat, then transfers the calories from the first heat exchanger to the interior air flow sent to the passenger compartment of the vehicle.

According to an advantageous characteristic, the means for closing the secondary circuit is an “all-or-nothing” type valve. The refrigerant circuit is divided into two circuits separating at a point of divergence and joining at a point of convergence, to form two parallel circuit portions. The primary circuit forms a loop going from the compression device to the second heat exchanger and the secondary circuit forms a loop going from the point of divergence to the point of convergence. The secondary circuit comprises a valve, adjustable according to two positions, open and closed, located between the point of divergence and the third heat exchanger. This valve is an embodiment of the closure means making it possible to isolate the secondary circuit from the rest of the refrigerant circuit. Indeed, in its open position, the valve allows the refrigerant fluid to circulate in the secondary circuit and to supply the third heat exchanger, while in its closed position, this valve makes it possible to isolate the secondary circuit from the rest of the circuit. of refrigerant fluid. Thus, in the closed position of the valve, the refrigerant fluid circulates only in the primary circuit while in the open position of the valve, the refrigerant fluid circulates both in the primary circuit and in the secondary circuit.

According to an advantageous characteristic, the expansion member is also the closure means. The expansion device can allow the circulation of the refrigerant fluid in the third heat exchanger or the prohibition of the circulation of refrigerant fluid within the third heat exchanger of the refrigerant circuit. The expansion device can advantageously communicate with equipment to modulate the access of the refrigerant fluid to the third heat exchanger according to the temperature of the internal air flow. When the expansion member is also the closure means, the latter performs the functions of expanding the refrigerant fluid and controlling the passage of the refrigerant fluid to the third heat exchanger.

According to one characteristic of the invention, the compression device regulates the temperature of the interior air flow by adapting its speed of rotation. It is understood that the rotational speed of the compression device can be adjusted, in response to an instruction given by the user of the vehicle, to modify the temperature of the interior air flow sent to the passenger compartment of the vehicle.

According to an advantageous characteristic, when a temperature of the interior air flow at the outlet of the third heat exchanger passes from the first temperature to the second temperature, the closure means is placed in its open position.

According to another advantageous characteristic, when the temperature of the interior air flow at the outlet of the third heat exchanger passes from the second temperature to the first temperature, the closure means is placed in its closed position. A temperature sensor, placed at the level of the air flow, at the outlet of the third heat exchanger, controls, at least indirectly, the closure means so that as soon as the temperature of the interior air flow at the outlet of the third heat exchanger reaches the second temperature, for example less than or equal to 3° C., the closure means is configured to pass into its closed position. The closure means then remains in this closed position as long as the temperature of the interior air flow at the outlet of the third heat exchanger is, for example, less than 7°C. This same temperature sensor controls, at least indirectly, the closure means so that as soon as the temperature of the interior air flow at the outlet of the third heat exchanger reaches the first temperature, for example greater than or equal to 7° C, the shutter means is configured to move into its open position. The closure means then remains in this open position as long as the temperature of the interior air flow at the outlet of the third heat exchanger is, for example, greater than 3°C.

According to one characteristic of the invention, the secondary circuit shutter means is alternately in an open position or in a closed position according to a periodic phenomenon forming a cycle of openings and closings of the shutter means. The open or closed position of the closure means depends on the temperature of the interior air flow at the outlet of the third heat exchanger. The passage of the closure means from its closed position to its open position takes place when the temperature of the interior air flow at the outlet of the third heat exchanger is, for example, at least 7° C. Similarly, the passage of the closure means from its open position to its closed position takes place when the temperature of the interior air flow at the outlet of the third heat exchanger is, for example, less than or equal to 3° C. Lowering the temperature by 7°C to 3°C and raising the temperature by 3°C to 7°C of the indoor air flow at the outlet of the third heat exchanger takes place over a time interval substantially equal. This fluctuation in the temperature of the interior air flow at the outlet of the third heat exchanger is a periodic phenomenon in which the number of times per unit time that the shutter means passes from its open position to its closed position reproduces a substantially similar number of times.

According to another characteristic of the invention, the cycle of openings and closings of the closure means takes place according to a frequency of less than three cycles per minute. This frequency represents the number of times that the shutter means operates an opening and closing cycle over a given unit of time. A cycle being defined by the passage of the closure means from an initial position to an intermediate position and then back to its initial position.

According to a characteristic of the invention, the temperature of the interior air flow at the outlet of the third heat exchanger is measured by at least one sensor installed at the level of the interior air flow at the outlet of the third heat exchanger. The process for dehumidifying the passenger compartment of the vehicle makes it possible to control the temperature of the interior air flow at the outlet of the third exchanger so that this temperature oscillates between the first temperature and the second temperature. Thus, this sensor communicates directly or indirectly with the closure means making it possible to control the supply of refrigerant fluid to the third heat exchanger so that the temperature of the refrigerant fluid at the outlet of the third exchanger changes between the first temperature and the second temperature. temperature.

According to another characteristic of the invention, the first threshold is a temperature between 5°C and 12°C. When the temperature of the air outside the vehicle interior is below 12°C, there is a risk that, during prolonged operation, the third heat exchanger will ice up. The dehumidification process makes it possible to mitigate this risk.

According to an advantageous characteristic, the refrigerant circuit comprises a device for accumulating the refrigerant fluid.

According to another characteristic of the invention, the second heat exchanger participates thermodynamically in increasing the temperature of the interior air flow by taking advantage of the heat captured in the exterior air flow. The second heat exchanger behaves like an evaporator and is a cold point in the refrigerant circuit by recovering calories from the outside air flow. These calories participate, according to the principles of thermodynamics, in increasing the temperature of the hot spot of the refrigerant circuit, this hot spot is the first heat exchanger. Raising the temperature of the first heat exchanger helps raise the temperature of the indoor airflow. Thus, the second heat exchanger participates in indirectly increasing the temperature of the interior air flow.

The present 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 compression device, a first heat exchanger,

an expansion element and a second heat exchanger, the secondary circuit being connected to the primary circuit in parallel with the second heat exchanger and the expansion element and comprising an expansion member and a third heat exchanger as well as at least a closure means capable of adopting a closed position in which the circulation of the refrigerant fluid is prevented within the secondary circuit and an open position allowing the circulation of the refrigerant fluid within the secondary circuit the primary circuit and the secondary circuit are traversed simultaneously by the refrigerant, the closure means being in its open position, characterized in that the refrigerant circuit implements the dehumidification process, the closure means being configured to be actuated cyclically.

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 dehumidification method according to the invention.

is a schematic representation of a variant of the refrigerant circuit implementing the dehumidification method according to the invention, in which the first heat exchanger is directly 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 graphic representation of the evolution of the temperature of the interior air flow at the outlet of the third heat exchanger as a function of time when the refrigerant circuit is used in an operating mode ensuring the dehumidification of the passenger compartment of the vehicle.

is a graphic representation of the evolution of the temperature of the interior air flow at the outlet of the radiator as a function of time when the refrigerant fluid circuit is used in an operating mode ensuring the dehumidification of the passenger compartment of the vehicle.

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 internal air flow. 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 illustrate a portion of the refrigerant fluid circuit where the refrigerant fluid does not circulate. In figures 3 to 5 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. Furthermore, when a valve is at a given time in its open position and at another given time in its closed position during operation of the refrigerant circuit, this valve is represented by a mixed black and white 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 first heat exchanger heat 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 first heat exchanger 2, which in the embodiment shown is a condenser, that is to say a heat exchanger in which the refrigerant fluid is condenses. The first heat exchanger 2 performs 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 first heat exchanger 2, to the heat transfer liquid of the loop of heat transfer liquid 200.

Thus, this heat transfer liquid transports the calories from the first 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 first 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 first heat exchanger 2. This heat transfer liquid loop 200 forms a closed loop in which a pump 22 ensures the circulation of the heat transfer liquid in this heat transfer loop. heat transfer liquid 200.

In an alternative embodiment, this first heat exchanger 2 can be directly installed in the installation 20. It is then not necessary to set up the heat transfer fluid loop 200.

The refrigerant, which has changed from a gaseous state to a liquid state, by condensation within the first heat exchanger 2, passes through an accumulation device 4 which, in the embodiment shown, is a dehydrating bottle intended to eliminate moisture and fine particles present in the refrigerant. It should be noted that this dehydrating bottle can advantageously be integrated into the first 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 second 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 second 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 second heat exchanger 13 which, in the embodiment shown, is an evapo-condenser located on the front 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 second heat exchanger 13 behaves like an evaporator. When the refrigerant fluid 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 second heat exchanger 13 behaves like a condenser. It should be noted that the second heat exchanger 13 is crossed by a flow of air outside the cabin 27 sent to the outside of the cabin. 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 second heat exchanger 13 reaches a first connection point 40, located downstream of the second 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 includes a non-return valve 10 which, when the refrigerant fluid passes through the bypass branch 26, prevents the passage of the refrigerant fluid from the secondary circuit 24 to the primary circuit 25, in particular when the cooling circuit refrigerant fluid 1 performs the cooling function.

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. 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 fluid from borrowing the primary circuit 25 beyond the connection point 40. The refrigerant fluid 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 second 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 a heat exchanger 16 which makes it possible to exchange 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 third 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 third 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 first heat exchanger 2, in the gaseous state at the outlet of the third 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 the radiator 8 and the third heat exchanger 7 which, in the embodiment shown, is used as an evaporator. The radiator 8 and the third heat exchanger 7 are traversed by an interior air flow 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 interior air flow 28 and on the one hand the third heat exchanger 7 and on the other hand the radiator 8. A temperature sensor 17 installed in the interior air flow 28 at the outlet of the third heat exchanger 7 measures the temperature of the interior air flow 28. This data relating to the temperature of the interior air flow 28 is transmitted to a management device, such as a computer, to modulate the position of the second valve 5a. It should be noted that in an alternative embodiment, the computer can also communicate this data relating to the temperature of the interior air flow 28 to the means of closure 5. The low-pressure refrigerant fluid, at the outlet of the third heat exchanger heat 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 5a modulate the refrigerant fluid circuit to allow the refrigerant fluid to circulate between the primary circuit 25, the secondary circuit 24 and the bypass branch 26. This adjustable 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 2 is installed in the installation 20 and operates a heat exchange with a fluid which, in the embodiment shown, is the interior air flow 28. This variant of the coolant circuit 1 allows it to dispense with the coolant loop 200.

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 and the second heat exchanger 13 is used as a condenser. The refrigerant undergoes a single expansion at the level of the expansion device 6. The internal air flow 28 performs a heat exchange with the third heat exchanger 7 so that the internal air flow 28 at the outlet of the 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 second heat exchanger 13, performing the function of evaporator, and from this second heat exchanger 13 to the compression device 9. In this configuration of the second valve 5a, the refrigerant fluid does not reach the third exchanger heat 7, which, not being supplied with refrigerant fluid, is thermally neutral. Within the installation 20, an exchange of calories takes place between the interior air flow 28 and the radiator 8 such that the interior air flow 28 is capable of increasing the temperature of the passenger compartment with respect to to the temperature outside the cabin. It should be noted that in the embodiment represented by the , the first heat exchanger 2 indirectly performs an exchange of calories with the air flow 28 by means of the heat transfer liquid loop 200.

There illustrates the refrigerant circuit 1 ensuring the dehumidification of the passenger compartment of the vehicle by overcoming the constraints of icing of the third heat exchanger 7 and by providing heating of the interior 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 first exchanger heat 2, the third heat exchanger 13 then behaves as an evaporator.

According to the method which is the subject of the invention, the second valve 5a is alternately in its open position, in which the third heat exchanger 7 is supplied with refrigerant fluid, and in its closed position, in which the second valve 5a prevents the refrigerant fluid to reach the third heat exchanger 7.

This alternation between the open position and the closed position of the second valve 5a is a function of the temperature of the interior air flow 28 at the outlet of the third heat exchanger 7. Thus, the temperature sensor 17 communicates information relating to the temperature from the interior air flow 28 at the outlet of the third heat exchanger 7 to a management device, such as a computer, which controls the second valve 5a. The second valve 5a is configured to be in its closed position when the temperature of the interior air flow 28 at the outlet of the third heat exchanger 7 is, in the embodiment shown, less than or equal to 3° C. and in its position open when the temperature of the interior air flow 28 at the outlet of the third heat exchanger 7 is, in the embodiment shown, greater than or equal to 7°C.

It should be noted that when the second valve 5a passes from its open position to its closed position, that is to say when the temperature of the interior air flow 28 at the outlet of the third heat exchanger 7 is less than or equal to 3° C., the third heat exchanger 7 is no longer supplied with refrigerant fluid and the temperature of the interior air flow 28 at the outlet of this third heat exchanger 7 gradually increases. Similarly, when the second valve 5a passes from its closed position to its open position, that is to say when the temperature of the interior air flow 28 at the outlet of the third heat exchanger 7 is greater than or equal to 7 ° C, the third heat exchanger 7 is supplied with refrigerant fluid and the temperature of the interior air flow 28 at the outlet of this third heat exchanger 7 gradually decreases.

Thus, the alternation between the closed position and the open position of the second valve 5a makes it possible to maintain the temperature of the internal air flow 28 at the outlet of the third heat exchanger 7 between substantially 3° C. and 7° C. without however impacting negatively the thermodynamic cycle which would lead, without the invention, to a slowing down of the speed of rotation of the compression device and consequently the impossibility of producing enough calories in the first heat exchanger 2 to ultimately heat the passenger compartment.

Furthermore, this alternation between the closed position and the open position of the second valve 5a makes it possible to maintain the temperature of the radiator 8 high enough to be able to heat the interior air flow 28 at the outlet of the third heat exchanger 7. Indeed, this alternation between the open position and the closed position of the second valve 5a makes it possible to maintain a high pressure level in the low pressure part of the refrigerant circuit 1. By maintaining the third heat exchanger 7 at a temperature level between 3° C. and 7° C., the coolant pressure in the low pressure part of the coolant circuit 1 makes it possible to maintain a high speed of rotation of the compression device 9. This speed of rotation of the compression device 9 makes it possible to maintain a high level of condensation at the level of the first heat exchanger 2, able to heat the interior air flow 28.

There illustrates a first graph 39 representing a first evolution of a temperature 31 of the interior air flow 28 at the third heat exchanger 7 outlet as a function of time 35. When the refrigerant circuit 1 is put into operation, according to its function dehumidification under conditions of outside temperature lower than a first threshold of 12° C., the second valve 5a is in its open position and the temperature 31 of the inside air flow 28 gradually decreases until it reaches a second temperature T2 which, in the embodiment shown, is substantially less than or equal to 3°C. When the temperature 31 of the interior air flow 28 at the outlet of the third heat exchanger 7 reaches this second temperature T2, the second valve 5a passes into its closed position and the temperature 31 of the interior air flow 28 gradually rises to reach a first temperature T1 which, in the embodiment shown, is substantially greater than or equal to 7°C. It should be noted that the temperatures T1 and T2 can be varied according to the desired temperature in the third heat exchanger 7. For example, the temperatures T1 and T2 can respectively be 3.8° C. and 3° C., thus the temperature in the third heat exchanger 7 oscillates between 3°C and 3.8°C.

When the temperature 31 of the interior air flow 28 at the outlet of the third heat exchanger 7 reaches this first temperature T1 having previously reached the second temperature T2, the second valve 5a switches to the open position and the temperature 31 of the air flow interior 28 gradually decreases until it again reaches the second temperature T2. Such a cycle repeats as time 35 elapses, as long as the prerequisites are met.

Thus, the alternation of passages between the open position and the closed position of the second valve 5a allows the temperature 31 of the interior air flow 28 at the outlet of the third heat exchanger 7 to oscillate around a first target temperature 32 which, in the embodiment shown, is substantially equal to 5°C, according to a periodic phenomenon in which each period represents a similar unit of time.

There illustrates a second graph 42 representing the evolution of a temperature 36 of the interior air flow 28 at the outlet of the radiator 8 as a function of time 35. When the refrigerant circuit 1 is put into operation, according to its dehumidification function under conditions of outside temperature below a first threshold, between 9° C. and 11° C., the temperature 36 of the interior air flow 28 at the outlet of the radiator 8 gradually increases until it stabilizes around a second temperature target 45 requested by the user.

Thus, the alternation between the open position and the closed position of the second valve 5a makes it possible to ensure the compression device 9 a speed of rotation greater than the speed of rotation that it would have taken without the cycling method according to the 'invention.

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.

The invention, as it has just been described, achieves the aims it had set itself, and makes it possible to propose a method for dehumidifying the passenger compartment of a vehicle by maintaining the temperature of the flow of interior air leaving the installation at a level high enough to ensure the comfort of the occupants of the vehicle, without the need to add an auxiliary heating system. Variants not described here could be implemented without departing from the context of the invention, provided that, in accordance with the invention, they include a dehumidification process in accordance with the invention.

Claims (11)

Method for dehumidifying the passenger compartment of a vehicle implementing a refrigerant circuit (1) of the vehicle through which a refrigerant fluid passes and comprising at least one primary circuit (25) and one secondary circuit (24), the primary circuit (25) comprising at least one device (9) for compressing the refrigerant fluid, a first heat exchanger (2) configured to effect a heat exchange between the refrigerant fluid and a fluid, an expansion element (12) and a second exchanger heat exchanger (13) configured to effect a heat exchange between the refrigerant fluid and a flow of air (27) outside the passenger compartment of the vehicle, the secondary circuit (24) being connected to the primary circuit (25) in parallel with the second heat exchanger (13) and the expansion element (12) and comprising an expansion member (6) and a third heat exchanger (7) configured to perform a heat exchange between the refrigerant fluid and an air flow interior (28) sent into the passenger compartment of the vehicle, the secondary circuit (24) comprising at least one closure means (5) capable of assuming a closed position in which the circulation of the refrigerant fluid is prevented within the secondary circuit ( 24) and an open position allowing the circulation of the refrigerant fluid within the secondary circuit (24), the primary circuit (25) and the secondary circuit (24) are traversed simultaneously by the refrigerant fluid, method of dehumidifying a passenger compartment a vehicle in which the expansion element (12) and the expansion member (6) operate an expansion and where the second heat exchanger (13) and the third heat exchanger (7) ensure the evaporation of the refrigerant characterized in that, at an air temperature outside the passenger compartment below a first threshold, the dehumidification process implements:
- at least a first step in which, at a temperature of the interior air flow (28) at the outlet of the third heat exchanger (7) higher than a first temperature (T1), the closing means (5) is placed in its open position,
- at least a second step in which, at a temperature of the interior air flow (28) at the outlet of the third heat exchanger (7) lower than a second temperature (T2), the closure means (5) is placed in its closed position, the second temperature (T2) being lower than the first temperature (T1). Process for dehumidifying a passenger compartment of a vehicle according to the preceding claim, characterized in that the first heat exchanger (2) raises the temperature of the interior air flow (28). Process for dehumidifying the passenger compartment of a vehicle according to any one of the preceding claims, characterized in that the means (5) for closing off the secondary circuit (24) is a valve (5a) of the "all-or-nothing" type. -Nothing ". Process for dehumidifying the passenger compartment of a vehicle according to any one of Claims 1 and 2, characterized in that the expansion member (6) is also the closing means (5). Process for dehumidifying the passenger compartment of a vehicle according to any one of the preceding claims, characterized in that the compression device (9) regulates the temperature of the interior air flow (28) by adapting its speed of rotation . Process for dehumidifying the passenger compartment of a vehicle according to any one of the preceding claims, characterized in that, when a temperature (31) of the interior air flow (28) leaving the third heat exchanger (7 ) passes from the first temperature (T1) to the second temperature (T2), the closure means (5) is placed in its open position. Process for dehumidifying the passenger compartment of a vehicle according to any one of the preceding claims, characterized in that when the temperature (31) of the interior air flow (28) leaving the third heat exchanger (7) passes from the second temperature (T2) to the first temperature (T1), the closure means (5) is placed in its closed position. Process for dehumidifying the passenger compartment of a vehicle according to any one of the preceding claims, characterized in that the first threshold is a temperature between 5°C and 12°C. Process for dehumidifying the passenger compartment of a vehicle according to any one of the preceding claims, characterized in that the cycle of openings and closings of the closure means (5) takes place according to a frequency of less than three per minute. Dehumidification process according to any one of the preceding claims, characterized in that the second heat exchanger (13) participates thermodynamically in increasing the temperature of the interior air flow (28) by taking advantage of the heat captured in the air flow. outside air (27). Cooling fluid circuit (1) comprising at least one primary circuit (25) and at least one secondary circuit (24), the primary circuit (25) comprising at least one compression device (9), a first heat exchanger (2 ), an expansion element (12) and a second heat exchanger (13), the secondary circuit (24) being connected to the primary circuit (25) in parallel with the second heat exchanger (13) and the expansion element (12) and comprising an expansion member (6) and a third heat exchanger (7) as well as at least one closure means (5) capable of assuming a closed position in which the circulation of the refrigerant fluid is prevented at the within the secondary circuit (24) and an open position allowing the circulation of the refrigerant fluid within the secondary circuit (24), the primary circuit (25) and the secondary circuit (24) are traversed simultaneously by the refrigerant fluid, the means of closure (5) being in its open position, characterized in that the refrigerant circuit (1) implements the dehumidification process according to any one of the preceding claims, the closure means (5) being configured to be operated cyclically.