FR3082786A1 - METHOD FOR CONTROLLING A REFRIGERANT FLUID CIRCUIT FOR VEHICLE - Google Patents

Abstract

The invention relates to a method (2) for controlling a circuit (1) of refrigerant fluid (FR) for a vehicle comprising a compression device (8), a first heat exchanger (16) arranged to be traversed by a flow of external air (FE), a second heat exchanger (21) arranged to be traversed by an internal air flow (FA), an expansion member (20) with variable section, an accumulation device (25), the control method (2) comprising a step (E3) of controlling the degree of opening (D) of the expansion member (20), the degree of opening (D) controlling a set subcooling (Tsbc) calculated using a condensation temperature (Tc), a temperature (Te) and a coefficient (A), according to a formula (F) [Tsbc = A x (Tc - Te)], where the coefficient (A) is function of an alpha factor between 0.68 and 1. Application to motor vehicles.

Description

The field of the present invention is that of refrigerant circuits and heat treatment systems including such refrigerant circuits, in particular for a motor vehicle. Motor vehicles are commonly equipped with refrigerant circuits used to heat or cool different areas or different components of the vehicle. It is notably known to use a refrigerant circuit for thermally treating an interior air flow sent into the passenger compartment of the vehicle.

A refrigerant circuit is known to include a couple of heat exchangers intended to carry out a thermodynamic cycle in order to supply energy capable of cooling the passenger compartment of the vehicle, whether during the use of the vehicle during driving phases, or when the vehicle is stopped. This pair of heat exchangers thus comprises a heat exchanger capable of operating as an evaporator and another heat exchanger capable of operating as a condenser. In order to cool the passenger compartment thanks to a cooled interior air flow, the heat exchanger capable of operating as an evaporator is crossed by this interior air flow which it treats thermally. In known manner, this evaporator is a part of a ventilation, heating and / or air conditioning installation equipping the vehicle.

The technical problem lies in the ability to cool the passenger compartment optimally, while limiting the consumption of the refrigerant circuit capable of fulfilling this function.

The invention is part of this context and proposes a technical solution which helps regulate the thermodynamic cycle taking place within the refrigerant circuit while ensuring adequate cooling of the interior air flow, that is to say by bringing this interior air flow to a temperature as expected in the passenger compartment of the vehicle. This technical solution is applied by means of a coolant circuit cleverly designed to regulate the state of the coolant, as a function of the temperature and pressure parameters noted in said circuit and in particular by obtaining an under temperature. -optimal cooling of the refrigerant.

The invention therefore relates to a method of controlling a refrigerant circuit for a vehicle, the refrigerant circuit comprising at least one device for compressing the refrigerant, a first heat exchanger arranged to be traversed by a flow of air outside a passenger compartment of the vehicle, a second heat exchanger arranged to be traversed by a flow of interior air sent into the passenger compartment of the vehicle, an expansion member with variable section disposed between the first heat exchanger and the second heat exchanger, an accumulation device disposed between the second heat exchanger and the compression device, the control method comprising at least one step of controlling the degree of opening of the expansion member, characterized in that the degree of opening controls a “Tsbc” subcooling of the refrigerant fluid output from the first exchanger t hermetic, the set sub-cooling “Tsbc” being calculated thanks to at least one condensing temperature “Te” of the refrigerant leaving the first heat exchanger, at a temperature “Te” of the external air flow and a coefficient "A", according to a defined formula such as [Tsbc = A x (Te - Te)], where the coefficient "A" is a function of an alpha factor between 0.68 and i.

"Tsbc" sub-cooling is a temperature of the refrigerant. The sub-cooling of a liquid sub-cooled to temperature and pressure (T, P) is the temperature difference between "Te" and "T". The condensation temperature “Te” is the saturation temperature of the refrigerant at the pressure considered measured or estimated at the outlet of the first heat exchanger. "T" is the measured temperature of the refrigerant leaving the first heat exchanger.

The refrigerant circuit is a closed circuit which implements a thermodynamic cycle.

The refrigerant compression device, which the refrigerant circuit includes, makes it possible to compress the refrigerant. The compression device is for example a compressor, and the invention finds a very particular application when the compressor is an electric compressor with fixed displacement and variable speed. It is thus possible to control the thermal power of the circuit according to the invention.

The refrigerant is for example a subcritical fluid, such as that known under the reference R134A or 1234YF.

The first heat exchanger can be installed on the front of the vehicle. This first heat exchanger can thus be used as a condenser. It can also be used as an evaporator when another heat exchanger is used as a condenser in the refrigerant circuit.

The accumulation device accumulates the circulating mass of refrigerant. The first heat exchanger is therefore devoid of a bottle.

The second heat exchanger is capable of operating as an evaporator. During the implementation of the second heat exchanger in an evaporator, an air flow is cooled by its passage through the first heat exchanger. The air flow thus modified thermally is then distributed in the passenger compartment of the vehicle. The second heat exchanger can be included in a ventilation, heating and / or air conditioning installation. In an exemplary implementation, the second heat exchanger used in the evaporator is coupled to the first heat exchanger used in the condenser.

The expansion member has a variable section intended to be taken up by the refrigerant. This section is variable in the sense that the trigger has a variable opening. Thus, the expansion member can be fully open or fully closed, but also be partially open according to different degrees of opening. The trigger is therefore configured to be able to generate different detents.

When the expansion member is fully open, that is to say that it has a degree of opening of 10%, the expansion member does not undergo any expansion of the refrigerant. When the expansion member is completely closed, that is to say that it has an opening degree of o%, the expansion member is not traversed by the refrigerant. Between these two situations, the opening is partial and the degree of opening between 1% and 99%. It is this degree of openness which is adapted during the process according to the invention.

The sub-cooling "Tsbc" set for the control process according to the invention corresponds to the temperature calculated according to the formula [Tsbc = Ax (Te - Te)]. The setpoint “Tsbc” subcooling is a “Tsbc” subcooling calculated to be optimal. It is the optimal sub-cooling that the refrigerant must reach in order for the thermodynamic cycle to be optimized in its energy performance. Its value varies according to the temperature data emanating from the circuit, this temperature data being able to vary.

The temperature “Te” of the outside air flow is the temperature of the air flow intended to pass through the first heat exchanger. This temperature is for example measured upstream of the first heat exchanger.

The condensation temperature “Te” is the saturation temperature of the refrigerant at the pressure considered measured or estimated at the outlet of the condenser. The pressure can be measured by the use of a pressure sensor at the outlet of the first heat exchanger. The pressure can also be estimated from the measurement of the pressure leaving the compression device.

The control step involves: integrating the temperature data, that is to say the condensation temperature “Te” of the refrigerant at the pressure measured or estimated at the outlet of the first heat exchanger and the temperature “Te »Outdoor air flow; the application of the formula in order to calculate the sub-cooling "Tsbc" setpoint at the outlet of the first heat exchanger; the correlation between this setpoint "Tsbc" sub-cooling and the degree of opening of the internal section of the expansion device to be obtained; the transmission of an instruction related to the degree of opening of the internal section to the expansion member; the adaptation of the degree of opening of the section of the expansion member.

Following this control step, the refrigerant circulating in the refrigerant circuit is caused to change state as soon as the degree of opening of the section of the expansion member has been modified. This change of state, following the modification of the expansion operated by the expansion member, influences both the pressure of the refrigerant fluid and its temperature, these characteristics being interdependent.

When the refrigerant circulates in the refrigerant circuit, the pressure of this refrigerant upstream of the expansion member is all the more important that the section of the expansion member is closed. The expansion is thus adjusted so that the refrigerant reaches the desired subcooling. The method according to the invention makes it possible to adapt the pressure of the coolant in the coolant circuit thanks to the expansion member in order to achieve optimal subcooling in relation to the thermal and energy needs of the vehicles. Optimizing subcooling also optimizes the compression device so that the load on the compression device is reduced to a minimum. This minimum load also allows an interior air flow to be brought to the right temperature.

According to one aspect of the invention, the control step is preceded by at least one data collection step, the data collected during the collection step being at least one high pressure value "HP" allowing the calculation the condensing temperature “Te” of the refrigerant leaving the first heat exchanger, a temperature “Tscdr” of the refrigerant leaving the first heat exchanger and the temperature “Te” of the external air flow entering the first heat exchanger. The data collection stage makes it possible to collect the temperature data extracted from the fluids in the circuit, in other words the refrigerant and the internal air flow, that is to say the condensation temperature “Te” of the refrigerant at the outlet of the first heat exchanger and the temperature “Te” of the external air flow. By extract means that the temperature data are measured or estimated beforehand at the collection stage. The temperature of the refrigerant fluid “Tscdr” at the outlet of the first exchanger is also measured.

The measured subcooling is then a value equal to [Te -Tscdr].

In what follows, the temperature “Te” of the external air flow is measured or estimated, the condensation temperature “Te” and the temperature of the refrigerant fluid “Tscdr” at the outlet of the first heat exchanger operating in condenser in mode is measured. cooling.

The data collection stage influences the control stage, since the degree of opening of the section of the trigger member is adapted according to the fluctuation of the data observed. The control step takes place in the context of adjusting the requirements of the refrigerant circuit, reflecting the cooling powers required for both the first heat exchanger and the second heat exchanger.

According to one aspect of the invention, a pressure of the coolant is measured in order to estimate the condensation temperature "Te" of the coolant at the outlet of the first heat exchanger. The pressure is measured by a pressure sensor placed in contact with the fluid. This sensor can be arranged at the outlet of the first heat exchanger or the sensor can be arranged at the outlet of the compressor, in this case the pressure is estimated. The condensing temperature “Te” of the refrigerant leaving the first heat exchanger is obtained by a calculation by applying the law of saturation of the refrigerant. Its estimate is calculated from the pressure of the refrigerant leaving the first heat exchanger. This calculation is for example performed at the pressure sensor. This pressure sensor is positioned in any portion of the circuit exposed to high pressure. For example, the pressure sensor is disposed between the compression device and the expansion member. This pressure sensor can also measure the pressure in the compression device which generates the high pressure.

According to one aspect of the invention, the temperature “Te” of the external air flow is measured by a temperature measurement device placed on the front face of the vehicle. In particular, the measuring device is positioned upstream of the first heat exchanger from the point of view of the outside air flow.

According to one aspect of the invention, the expansion member is placed under the dependence of an electronic control module. The trigger is electronically controlled by the electronic control module. The electronic control module is separate from the trigger. Alternatively, the electronic control module is integrated into the trigger.

According to one aspect of the invention, an electronic control module implements the step of collecting the data as well as the step of controlling the expansion device as a function of the data. Thus, the electronic control module is electronically connected to the temperature sensor and / or the pressure sensor, to the temperature measurement device, as well as to the expansion device. It gives them measurement and possibly calculation instructions for collecting temperature data.

The electronic control module receives data from the temperature sensor and / or the pressure sensor and the temperature measurement device.

The control module has a computer capable of integrating the temperature data. This computer is also able to apply the formula [Tsbc = A x (Te - Te)] in order to calculate the sub-cooling “Tsbc” of setpoint which is to be reached at the output of the first heat exchanger.

To choose the appropriate degree of opening of the trigger, the electronic control module implements an algorithm for varying the opening of the trigger. The latter is a function of the difference between the set subcooling and the subcooling calculated from high pressure "HP" measurements and the temperature of the refrigerant "Tscdr" at the outlet of the first heat exchanger operating as a condenser. The control module therefore transmits to the trigger the instruction related to the degree of opening of the trigger to be applied.

According to one aspect of the invention, the first heat exchanger is used as a condenser while the second heat exchanger is used as an evaporator. The second heat exchanger is then intended to cool the internal air flow passing therethrough in order to cool, for example, the passenger compartment of the vehicle. The heat emitted by the circuit is dispersed by the air flow outside the vehicle thanks to the first exchanger, for example on the front of the vehicle.

According to one aspect of the invention, the coefficient “A” is a function of the alpha factor, of a constant “B”, of the condensation temperature “Te” of the refrigerant leaving the first heat exchanger and of the temperature “Te »Of the outside air flow and responds to a defined equation such as [A = alpha x (Te Te) b].

In an exemplary embodiment, the alpha factor is between 0.8 and i. In a particular example, the alpha factor is 0.9756.

In an exemplary embodiment, the constant "B" is equal to 0.937.

According to an alternative aspect of the invention, the coefficient is a function of the alpha factor, of a value "D", of the condensation temperature "Te" of the refrigerant leaving the first heat exchanger, of the temperature "Te" of the outside air flow and a beta factor and responds to a defined expression such as [A = alpha + beta x (Te - Te) ^D ].

In an exemplary embodiment, the alpha factor is between 0.68 and 0.72. In a particular example, the alpha factor is 0.7.

In an exemplary embodiment, the beta factor is between 0.1 and 0.12. In a particular example, the beta factor is 0.1.

In an exemplary embodiment, the value "D" is equal to -0.07.

The invention also relates to a refrigerant circuit comprising at least one device for compressing the refrigerant, a first heat exchanger arranged to be traversed by a flow of air outside a passenger compartment of the vehicle, a second heat exchanger arranged to be traversed by an internal air flow sent into the passenger compartment of the vehicle, a variable-section expansion member disposed between the first heat exchanger and the second heat exchanger, an accumulation device disposed between the second heat exchanger and the compression device , and where the circuit is configured to implement the method as previously described above.

Other characteristics, details and advantages of the invention will emerge more clearly on reading the description given below by way of indication in relation to the drawings in which:

- Figure i is a schematic view of a refrigerant circuit to which a method according to the invention is applied,

FIG. 2 schematically illustrates the refrigerant circuit shown in FIG. i, operated according to an operating mode consisting in cooling a passenger compartment of a vehicle,

- Figure 3 is a flow diagram describing an implementation of the method according to the invention.

It should first be noted that the figures show the invention in detail for its implementation, said figures can of course be used to better define the invention, if necessary. These figures are schematic representations which illustrate how a refrigerant circuit is made to which a process according to the invention is applied, what makes it up and how a refrigerant circulates within it. In particular, the refrigerant circuit to which a method according to the invention is applied mainly comprises a device for compressing the refrigerant, a first heat exchanger, a second heat exchanger, an expansion member with variable section, an accumulation device .

The terms upstream and downstream used in the description which follows refer to the direction of circulation of the fluid considered. In order to differentiate the components, the terms "first", "second", ... are used. These terms are not intended to prioritize or order components. These terms are used as a distinction and may be reversed without prejudice to the implementation of the invention.

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For FIG. 2, the different components of the refrigerant circuit are explained in a direction of circulation of the refrigerant. In the refrigerant circuit, lines symbolizing pipes connecting the components are solid when they illustrate a portion of the circuit where the fluid to be considered circulates, while dotted lines show an absence of circulation of said fluid. Components that are inoperative from the point of view of the refrigerant are also signified by dotted lines.

In the refrigerant circuit represented in FIG. 2, the refrigerant is symbolized by a long arrow which illustrates a direction of circulation of the latter in the pipe considered. Thick lines and a solid arrow are used to symbolize a refrigerant in a state of high pressure and high temperature. Thin lines and a hollow arrow correspond to a fluid in a state of low pressure and low temperature.

Referring first to Figure i, we see a refrigerant circuit i. This coolant circuit i is able to operate in a mode allowing to ventilate, heat and / or air-condition a passenger compartment of a vehicle.

The coolant circuit i to which a method 2 according to the invention is applied is a closed circuit which comprises a network of conduits 3, 4, 5 connecting the components of the coolant circuit 1. The network of pipes 3, 4, 5 is constructed so that certain components are arranged in series and others in parallel. The network of pipes 3, 4, 5 thus comprises a main pipe 3, a first branch 4 and a second branch 5.

The main pipe 3 extends between a first connection point 6 and a second connection point 7. The first branch 4 extends between the second connection point 7 and the first connection point 6. The components of the first branch 4 are in series with respect to the components of the main pipe 3 and in parallel with those of the second branch 5. The second branch 5 extends between the second connection point 7 and the first connection point 6. The components of the second branch 5 are in series with respect to the components of the main pipe 3 and in parallel with those of the first branch 4.

The coolant circuit 1 comprises, in the main line 3, a device 8 for compressing the coolant. It will be noted that the compression device 8 can take the form of an electric compressor, that is to say a compressor which includes a compression mechanism, an electric motor and an electric control and conversion unit. The compression mechanism of the compression device 8 is rotated by the electric motor, the latter being able to be housed inside a compressor housing common to the compression mechanism.

In a particular example, the compression device 8 for the refrigerant fluid has an inlet 9 and an outlet 10. The outlet 10 of the compression device 8 is connected to a heat exchanger 11. This heat exchanger 11 is for example a condenser arranged in a housing 12 of an installation 13 for ventilation, heating and / or air conditioning of the vehicle of which it is a part.

Within the main pipe 3 and between the compression device 8 and the heat exchanger 11, a pressure sensor 14 is positioned. This pressure sensor 14 is configured to come into contact with the refrigerant leaving the compression device 8.

An expansion device 15 is positioned downstream of the heat exchanger 11 on the coolant circuit 1. Between the expansion device 15 and the second connection point 7, the refrigerant circuit 1 includes a first heat exchanger 16. The first heat exchanger 16 is disposed on the front of the vehicle. The first heat exchanger 16 is associated with a temperature sensor 17 dedicated to measuring a temperature of the refrigerant. This temperature sensor 17 is configured to come into contact with the refrigerant leaving the first heat exchanger 16. A temperature measuring device 18, dedicated to measuring the temperature of an air flow outside the vehicle, is also positioned on the front face of the vehicle, upstream of the first heat exchanger 11 from the point of view of the outside air flow.

The refrigerant circuit 1 comprises, in the first branch 4, a non-return valve 19 disposed between the second connection point 7 and an expansion member 20. The expansion member 20 is of variable section.

The first branch 4 also comprises, between the expansion member 20 and the first connection point 6, a second heat exchanger 21. The second heat exchanger 21 is for example an evaporator arranged in the housing 12 of the installation 13 of ventilation, heating and / or air conditioning of which it is a part. From the point of view of an air flow inside the vehicle brought through the installation 13 for ventilation, heating and / or air conditioning, the second heat exchanger 21 is arranged upstream of the heat exchanger

11. The housing 12 also comprises a set of flaps 22 intended to direct the interior air flow within it, the interior air flow being circulated in the housing 12 by means of a device 23 for setting in motion the indoor air flow. The device for setting in motion 23 the internal air flow is for example a propeller rotated by an electric motor.

The coolant circuit 1 comprises, on the second branch 5, a stop valve 24. The stop valve 24 is intended to authorize or block the circulation of the coolant in the second branch 5.

An accumulation device 25 is positioned in the main pipe 3 between the first connection point 6 and the inlet 9 of the compression device

8.

An electronic control module 26, intended to implement the method 2 according to the invention, is connected to different components of the refrigerant circuit 1 by electrical cables 27. The electronic control module 26 is connected to the temperature sensor 17 downstream at the first heat exchanger 16, at the pressure sensor 14 downstream at the compression device 8, and at the temperature measurement device 18 on the front face of the vehicle.

Furthermore, the electronic control module 26 is electrically connected to the temperature measurement device 18 via an electric wire 28.

FIG. 2 illustrates an operating mode of the refrigerant circuit 1 FR allowing the heat treatment of the passenger compartment of the vehicle. The implementation of the method 2 according to the invention makes it possible to regulate the thermodynamic cycle of this circuit i by adjusting the expansion of the refrigerant fluid FR, expansion carried out by the expansion member 20. An adapted expansion makes it possible to achieve a sub- “Tsbc” setpoint cooling, optimal in relation to the observed temperature context. The sub-cooling "Tsbc" setpoint is defined by the electronic control module 26 from the temperature data "Te, Te" that it receives.

In the main pipe 3, a high pressure HP is imposed on the refrigerating fluid FR by the compression device 8. This high pressure HP can be measured at the pressure sensor 14 at the outlet of the compression device 8. It could also be measured by means of a pressure sensor disposed at the outlet of the first heat exchanger 16.

This is for example the electronic control module 26 which sends a setpoint relating to this measurement to the pressure sensor 14. It is by the electric cable 27 connecting the electronic control module 26 to the pressure sensor 14 that the electronic control module 26 transmits instructions and receives the data obtained following these instructions. In another example, the measurement is taken continuously, or even at regular intervals.

In an exemplary embodiment, the pressure sensor 14 is capable of converting the data of refrigerant fluid pressure FR measured into a data of condensation temperature “Te” of the refrigerant fluid FR before transmitting said data of temperature “Te” to the module electronic control 26.

Downstream of the pressure sensor 14, the refrigerant FR passes through the heat exchanger 11. The latter is inoperative, so that the refrigerant FR does not undergo a change of state within the heat exchanger 11. In the same way, the refrigerant FR then passes through the expansion device 15 also made inoperative. The expansion device 15 is in fact completely open and the refrigerant FR does not undergo expansion.

The refrigerant FR, in the main pipe 3, enters the first heat exchanger 16. The first heat exchanger 16 operates, in this operating mode, as a condenser. It is simultaneously traversed by the air flow outside FE to the vehicle and by the refrigerant FR at high pressure HP and high temperature HT. The outside air flow FE disperses the calories of the refrigerant FR.

The temperature “Te” of the outside air flow FE is measured by the temperature measurement device 18 on the front face of the vehicle. The electronic control module 26 gives for example the instructions relating to these measurements. It is by the electric cable 27 connecting the electronic control module 26 to the temperature measurement device 18 and by the electric wire 28 electrically connecting the electronic control module 26 to the temperature measurement device 18 that the electronic control module 26 transmits instructions and receives the data obtained following these instructions. In another example, the measurement is taken continuously, or even at regular intervals.

In the operating mode described in FIG. 2, the refrigerant FR having passed through the first heat exchanger 16 successively passes through the second connection point 7 and the non-return valve 19 before passing through the expansion member 20. The refrigerant FR circulates in the first branch 4 and not in the second branch 5. The stop valve 24 of the second branch 5 is closed, preventing the circulation of the refrigerant fluid FR in the second branch 5.

The expansion member 20 operates an expansion of the refrigerating fluid FR. To do this, it adopts a partial opening of its internal section corresponding to a given degree of opening. Any change in the degree of opening of the section internal to the expansion member 20 impacts the state of the FR refrigerant on the entire circuit 1 of FR refrigerant. This degree of opening is defined and obtained by the method 2 according to the invention as will be described for FIG. 3. The instructions relating to this degree of opening are transmitted to the expansion member 20 via the electric cable 27 connecting it to the electronic control module 26.

Passing through the expansion member 20, the refrigerant FR passes from high pressure HP to low pressure BP and from high temperature HT to low temperature BT. When the method 2 according to the invention is implemented, then this expansion induces a sub-cooling "Tsbc" of the set point of the refrigerant fluid FR at the outlet of the first heat exchanger 16.

The refrigerant FR at low pressure BP and low temperature BT passes through the second heat exchanger 21. In the operating mode described in FIG. 2, the second heat exchanger 21 operates as an evaporator. It cools the interior air flow FA to the vehicle using the refrigerant FR with which the heat exchange takes place. Thus, when the internal air flow FA integrates the housing 12 of the ventilation, heating and / or air conditioning installation 13 driven by the movement device 23, it gives up its calories to the refrigerant fluid FR flowing through the second heat exchanger 21. Within the housing 12, the interior air flow FA is directed by the set of flaps 22 towards the passenger compartment of the vehicle, and this without passing through the heat exchanger 11, one of the flaps of the set flaps 22 by blocking access.

Downstream of the second heat exchanger 21, the refrigerating fluid FR joins the main pipe 3 via the first connection point 6. The refrigerating fluid FR then accumulates in the accumulation device 25 before ending its thermodynamic cycle by passing the input 9 of the compression device 8.

FIG. 3 shows a flow diagram describing an implementation of method 2 according to the invention. The flowchart is a graphic representation using geometric symbols, each geometric symbol being characterized by a top, a bottom, a left side, a right side. Each geometric symbol represents a step in process 2 according to the invention. Thus, an ellipse represents a stage which intervenes automatically in process 2 and a rectangle represents a stage of action. Arrows are also used to represent connections between these steps. In the flow diagram, a step entry is made from the top of the geometric symbol, a step exit from the bottom or the right side of the geometric symbol.

The method 2 according to the invention is implemented following the measurements taken at different points of the circuit 1 of refrigerant fluid FR. The electronic control module 26 gives for example the instructions relating to these measurements. In another example, the measurements are iterative or continuous.

The temperature “Te” of the outside air flow FE is measured by the temperature measurement device 18 on the front face of the vehicle. A temperature of the coolant “Tscdr” at the outlet of the first heat exchanger 16 is measured by the temperature sensor 17 at the outlet of the first heat exchanger 16. The condensation temperature “Te” of the coolant FR is calculated from the reading of the high pressure HP, high pressure HP measured at the pressure sensor 14 at the outlet of the compression device 8 or a pressure sensor disposed at the outlet of the first heat exchanger 16.

Obtaining the temperature data “Te, Te, Tscdr”, by measurement or estimation, constitutes a step “El” for obtaining the temperatures. The "El" step of obtaining temperatures is prior to a "E2" step of collecting these same temperatures.

The collection step “E2” makes it possible to collect the temperature data “Te, Te, Tscdr” corresponding to the condensation temperature “Te” of the refrigerant fluid FR at the outlet of the first heat exchanger 16, the temperature “Te” of the flow of outside air FE and at the temperature of the refrigerant fluid “Tscdr” at the outlet of the first heat exchanger 16. It is for example the electronic control module 26 which performs the collecting step “E2”.

The electronic control module 26 then implements a control step “E3”. This control step “E3” is that which leads, in the refrigerant circuit 1, to obtaining a sub-cooling “Tsbc” of setpoint following the integration of the temperature data “Te, Te, Tscdr ”collected. The control step "E3" comprises at least four sub-steps defined below.

A first sub-step "E3.1" integrates the temperature data "Te, Te, Tscdr". This first sub-step “E3.1” makes it possible to calculate the set subcooling “Tsbc” which is to be achieved at the output of the first heat exchanger 16, by applying a formula “F”: [Tsbc = A x (Te - Te) ], where a coefficient "A" is a function of an alpha factor between 0.68 and 1. The formula "F" is applied by a computer 29 integrated into the electronic control module 26.

A second sub-step “E3.2” assigns the calculated sub-cooling “Tsbc” to a control of the degree of opening “D” of the variable section of the expansion member 20. This allocation is done by means of a defined algorithm. It is during this second sub-step “E3.2” that it is determined which instruction will be transmitted to the expansion member 20 by the electronic control module 26. This instruction will be linked to the difference between the sub-cooling “Tsbc” setpoint with respect to the sub-cooling temperature calculated from the measurement of the temperature of the refrigerant fluid “Tscdr” at the outlet of the first heat exchanger 16 via the sensor 17 and the condensation temperature “Te”.

During a third sub-step "E3.3", the instruction relating to the opening of the variable section taken by the refrigerant FR is transmitted. The degree of opening "D" of the variable section of the expansion member 20 is thus adapted to achieve the sub-cooling "Tsbc" setpoint calculated during the first sub-step "E3.1".

The fourth sub-step “E3.4” consists in modifying the degree of opening “D” of variable section of the trigger member 20. This modification is for example carried out in the trigger member 20. This fourth sub -step “E3.4” can also be carried out by the electronic control module 29. The opening of the variable section of the expansion member 20 is thus adapted with the aim of achieving “Tsbc” subcooling setpoint calculated during the first sub-step "E3.1". It is understood that, if the expansion member 20 is already at the desired degree of opening "D", the instruction provided has no consequence on the variable section.

At the end of the control step "E3", the pressures within the refrigerant circuit 1 FR adjust. Consequently, the temperature of the refrigerating fluid FR at the outlet of the first heat exchange 16 changes until the sub-cooling "Tsbc" of setpoint, calculated during the first sub-step "E3.1", is reached. The load of the compression device 8 is therefore also modified. Method 2 according to the invention incorporates feedback since the "El" step of obtaining temperatures is again performed consecutively to the "E3" control step.

It is understood from the foregoing that the present invention thus makes it possible to ensure a heat treatment adjusted to the needs of the occupants of the vehicle while optimizing the energy efficiency of the refrigerant fluid circuit involved in this heat treatment. The present invention has the advantage of exploiting an optimal sub-cooling of the refrigerant determined as a function of the temperatures observed on the circuit and the cooling requirements. In particular, the invention aims to adapt the pressure of the refrigerant in the circuit by implementing the control of the expansion operated by the expansion member 20 forming part of the circuit.

The invention cannot however be limited to the means and configurations described and illustrated here, and it also extends to all equivalent means or configurations and to any technically operating combination of such means. In particular, the architecture of the refrigerant circuit or of the heat transfer fluid loop can be modified without harming the invention insofar as it fulfills the functionalities described in this document.

Claims (9)

1. Method (2) for controlling a circuit (1) of refrigerant (FR) for a vehicle, the circuit (1) of refrigerant (FR) comprising at least one compression device (8) for the refrigerant (FR) ), a first heat exchanger (16) arranged to be traversed by an exterior air flow (FE) to a passenger compartment of the vehicle, a second heat exchanger (21) arranged to be traversed by an interior air flow (FA) sent to the passenger compartment of the vehicle, an expansion member (20) with variable section arranged between the first heat exchanger (16) and the second heat exchanger (21), an accumulation device (25) disposed between the second heat exchanger (21) and the compression device (8), the control method (2) comprising at least one step (E3) for controlling the degree of opening (D) of the expansion member (20), characterized in that that the degree of openness (D) controls sub-cooling (Tsbc) d e setpoint of the coolant (FR) at the outlet of the first heat exchanger (16), the set subcooling (Tsbc) being calculated using a condensing temperature (Te) of the coolant (FR) at the outlet of the first heat exchanger (16 ), at a temperature (Te) of the outside air flow (FE) and at a coefficient (A), according to a formula (F) defined such that [Tsbc = A x (Te - Te)], where the coefficient ( A) is a function of an alpha factor between 0.68 and 1. 2. Control method (2) according to claim 1, in which the control step (E3) is preceded by at least one step (E2) of collecting data (Te, Te, Tscdr), the data (Te , Te, Tscdr) collected during the collection step (E2) being at least one high pressure value (HP) allowing the calculation of the condensation temperature (Te) of the refrigerant fluid (FR) at the outlet of the first heat exchanger (16), a temperature (Tscdr) of the refrigerant (FR) at the outlet of the first heat exchanger (16) and the temperature (Te) of the external air flow (FE) at the inlet of the first heat exchanger (16). 3. Control method (2) according to any one of the preceding claims, in which a pressure of the coolant (FR) is measured in order to estimate the condensation temperature (Te) of the coolant (FR) at the outlet of the first heat exchanger (16). 4 · control method (2) according to any one of the preceding claims, wherein the expansion member (20) is placed under the control of an electronic control module (26). 5. Method (2) of control according to the preceding claim in combination with claim 2, wherein an electronic control module (26) implements the step (E2) of data collection (Te, Te, Tscdr) as well that the step (E3) for controlling the expansion member (20) as a function of the data (Te, Te, Tscdr). 6. Control method (2) according to any one of the preceding claims, in which the first heat exchanger (16) is used as a condenser while the second heat exchanger (21) is used as an evaporator. 7. Control method (2) according to any one of the preceding claims, in which the coefficient (A) is a function of the alpha factor, of a constant (B), of the condensation temperature (Te) of the refrigerant fluid ( FR) at the outlet of the first heat exchanger (16) and of the temperature (Te) of the external air flow (FE) and responds to a defined equation such as [A = alpha x (Te - Te) ^B ]. 8. Control method (2) according to any one of claims 1 to 6, in which the coefficient (A) is a function of the alpha factor, of a value (D), of the condensation temperature (Te) of the fluid refrigerant (FR) at the outlet of the first heat exchanger (16), the temperature (Te) of the external air flow (FE) and a beta factor and responds to a defined expression such as [A = alpha + beta x (Te-Te) ^D ]. 9. Refrigerant fluid circuit (1) (FR) comprising at least one compression device (8) for the refrigerant fluid (FR), a first heat exchanger (16) arranged to be traversed by an external air flow (FE) in a passenger compartment of the vehicle, a second heat exchanger (21) arranged to be traversed by an internal air flow (FA) sent into the passenger compartment of the vehicle, an expansion member (20) of variable section disposed between the first exchanger heat (16) and the second heat exchanger (21), an accumulation device (25) disposed between the second heat exchanger (21) and the compression device (8), and where the circuit (1) is configured to put implementing the method (2) according to any one of the preceding claims.