Device and Method for Automatically Leveling the Heat Transfer Fluid of an Air Conditioning System

Abstract

The invention relates to an air conditioning system (1) of the type with a two-phase liquid / vapor heat transfer fluid (7) circulating in a two-phase loop (15) comprising a compressor (2) and an expansion valve (4), the air conditioning system (1) comprising: - a main tank (4) of heat transfer fluid (7) included / inserted / included in the two-phase loop (15), - a second tank, called a make-up tank (11), connected in sealed communication of heat transfer fluid (7) with a part (19) of the two-phase loop (15) extending downstream of the compressor (2) and upstream of the expansion valve (4),characterized in that said top-up tank (11) is provided with a member (16) for heating the heat transfer fluid (7) contained in said top-up tank (11) and adapted to be able to vaporize at least a portion of the heat transfer fluid (7) in said top-up tank (11) and to be able to bring the pressure of the heat transfer fluid (7) in said top-up tank (11) to a pressure of a value higher than the pressure value of the heat transfer fluid (7) in said part (19) of the two-phase loop (15) and to allow a flow of heat transfer fluid (7) in said part (19) of the two-phase loop (15) from said top-up tank (11). Figure for the abstract: Fig.2,

Description

Title of the invention: Device and Method for Automatically Leveling the Heat Transfer Liquid of an Air Conditioning System Technical field

[0001] The invention relates to a device and a method for automatically topping up the heat transfer fluid in an air conditioning system, in particular but not exclusively in an air conditioning system of a motor vehicle. The invention also extends to a motor vehicle equipped with such a device for automatically topping up the heat transfer fluid of the air conditioning system. Prior art

[0002] A conventional air conditioning system, in particular a conventional air conditioning system 1' for a motor vehicle, is shown schematically in [Fig.l]. This known system 1' comprises an electric or mechanical compressor 2', a condenser 3', a main tank 4' containing a refrigeration fluid 7', an expansion valve 5' and an evaporator 6'. The refrigeration fluid 7' circulates in a closed loop 15' of refrigeration fluid 7' shown in [Fig.l] by thick lines. The refrigeration fluid 7' changes from a liquid state to a gaseous state and vice versa depending on the pressure and temperature to which it is exposed. During operation of the known system 1', the high-pressure refrigeration fluid 7' enters the expansion valve 5', whereby its pressure drops, then immediately into the evaporator 6', in which, by capturing the calories of a fluid 9' to be cooled, it evaporates and passes into the gaseous state.Leaving the evaporator 6', it passes back into the expansion valve 5', in which its temperature is measured for the purpose of controlling the operation of the expansion valve 5'. The refrigeration fluid 7' in the gaseous state is sucked in by the compressor 2' in which its pressure increases by compression. This compression also increases the temperature of the refrigeration fluid 7' in the gaseous state. The refrigeration fluid 7' in the gaseous state and at high pressure passes into the condenser 3' in which it is cooled by another fluid 10', whereby the refrigeration fluid 7' in the gaseous state returns to the liquid state. The heat energy captured by a fluid 10' can be used to heat a component of the vehicle or released into the ambient air. The 7' refrigeration fluid in liquid state and at high pressure enters the main 4' tank, in which it is filtered to remove the humidity it carries and any impurities.It is then drawn towards the expansion valve 5'. In normal operating mode, the level of the refrigeration fluid 7' in the liquid state is higher than a minimum threshold level in the main tank 4'.

[0003] In these air conditioning systems 1' of a motor vehicle, the level of refrigeration fluid 7' in the liquid state must be periodically checked by means of a display by the user of the vehicle or by a professional specialized in the maintenance of motor vehicles to anticipate a breakdown of the air conditioning system 1' due to a lack of refrigeration fluid 7'.

[0004] In other air conditioning systems 1' of a motor vehicle such as shown schematically in [Fig.l], the main tank 4' is provided with a member 14' for measuring the level of refrigeration fluid 7' in the liquid state in the main tank 4', this level measuring member 14' being configured to be able to alert the user by a display on the dashboard of the vehicle of a lack of refrigeration fluid 7', prior to a loss of functionality of the air conditioning system due to this lack of refrigeration fluid 7'.

[0005] In the situation of a lack of refrigeration fluid 7' in the air conditioning system 1' and / or a non-conformity of the quantity of refrigeration fluid 7' with regard to the manufacturer's instructions, this lack or this non-conformity being detected visually or automatically, the functionality of the air conditioning system 1' may be restored by adding refrigeration fluid 7' to the closed loop 15' of refrigeration fluid 7'. Since this is a refrigeration fluid 7' that may be flammable, such as propane, this addition may present risks for the technician responsible for carrying out this addition and / or for the vehicle itself.

[0006] The invention aims firstly to overcome this drawback.

[0007] In certain other air conditioning systems 1' of a motor vehicle, provision is made for automatic supplementation of refrigeration fluid 7' in the closed loop 15' of refrigeration fluid 7', as soon as the member 14' for measuring the level of refrigeration fluid 7' in the liquid state of the main tank 4' detects an insufficient level of refrigeration fluid 7' in the liquid state in the main tank 4'. In these air conditioning systems 1' with supplementation by automatic supply of refrigeration fluid 7', refrigeration fluid 7' is pumped from a make-up tank containing a quantity of the same refrigeration fluid as the refrigeration fluid 7' of the closed loop 15' (or a refrigeration liquid compatible with the refrigeration fluid 7') and introduced on demand into the closed refrigeration loop 15'.Taking into account the respective pressures of the refrigeration fluid 7' in the booster tank and in the closed loop 15', this introduction requires volumetric pumping of the refrigeration fluid 7' for the purpose of its introduction into the closed refrigeration loop 15', with a pressure higher than the pressure of the part of the refrigeration loop 15' into which the refrigeration fluid 7' is to be introduced. Such volumetric pumping of refrigeration fluid 7' under . high pressure can be complex. Since this is a pumping operation implemented using a rotary shaft volumetric pump, there are risks of refrigeration fluid leakage due to the implementation of this rotary shaft volumetric pump. In addition, since this is a pumping operation implemented using a volumetric pump chosen to limit the risk of leakage, this solution is more expensive.

[0008] The invention also aims to overcome this drawback.

[0009] Furthermore, document CN115416441 discloses an air conditioning system comprising two separate reservoirs for the refrigerant fluid of a refrigeration circuit, one of which is for compensating for the variation in the volume of refrigerant fluid in the refrigeration circuit.

[0010] The invention also aims to overcome all of the drawbacks mentioned above. Statement of the invention

[0011] The invention relates to an air conditioning system of the liquid / vapor two-phase heat transfer fluid type circulating in a two-phase loop and comprising a compressor and an expander, the air conditioning system comprising: - a main heat transfer fluid tank inserted in the two-phase loop, - a second tank, called a booster tank, connected in sealed communication of heat transfer fluid with a part of the two-phase loop extending downstream of the compressor and upstream of the expansion valve, characterized in that said booster tank is provided with a member for heating the heat transfer fluid contained in said booster tank and adapted to be able to vaporize at least a part of the heat transfer fluid in said booster tank and to be able to bring the pressure of the heat transfer fluid in said booster tank to a pressure of a value higher than the pressure value of the heat transfer fluid in said part of the two-phase loop and to allow a flow of heat transfer fluid into said part of the two-phase loop from said booster tank.

[0012] Throughout the text, the terms "upstream" and "downstream" are defined in relation to the direction of flow of the heat transfer fluid in the two-phase loop, the heat transfer fluid flowing in the two-phase loop successively into the compressor, then into the condenser, then into the main tank, then into the evaporator and in the direction of circulation indicated by the arrows shown on the two-phase loop in [Fig.2].

[0013] Any type of heat transfer fluid that complies with current regulations may be used. This may be a heat transfer fluid of the R1234yf type (2,3,3,3-tetrafluoropropene, CAS 754-12-1) used in the air conditioning of most private vehicles. However, there is nothing to prevent the use of a substantially non-flammable heat transfer fluid, in particular carbon dioxide (CO2) as the heat transfer fluid. In particular, CO2 can be used as a heat transfer fluid at a pressure of the order of 50 bars in said auxiliary tank and at a temperature of the order of 20°C, the pressure of which increases to a value of the order of 70 bars by heating the heat transfer fluid in said auxiliary tank to a temperature of the order of 40°C. There is also nothing to prevent the use of propane as a heat transfer fluid, due to the advantage provided by the invention, in particular the automatic leveling of the heat transfer fluid in the two-phase loop, without requiring human intervention.

[0014] Advantageously, the heat transfer fluid being propane, the two-phase loop of the air conditioning system has a volume accessible to the heat transfer fluid (excluding the auxiliary tank) of between around 10 L and around 20 L.

[0015] According to the invention, the use of such a heat transfer fluid requires and necessitates reinforced sealing of the two-phase loop. Throughout the text, it follows from the expression "two-phase loop" that the two-phase loop is hermetically sealed and sealed to the heat transfer fluid in the liquid state and to the heat transfer fluid in the gaseous state and at any heating temperature of the heat transfer fluid. The expression "two-phase loop" means a liquid / vapor two-phase loop in which the heat transfer fluid passes from the gaseous state to the liquid state by compression and from the liquid state to the gaseous state by expansion.

[0016] According to certain embodiments, the air conditioning system is an air conditioning system for a motor vehicle. It may be a motor vehicle with a thermal engine or with an electric or hybrid engine. However, nothing prevents the air conditioning system from being an air conditioning system for a home.

[0017] According to certain embodiments, the compressor is a mechanical compressor, i.e. a compressor functionally driven by a mobile drive element of the motor vehicle. According to certain of these embodiments, the mechanical compressor is a mechanical compressor of a thermal vehicle. According to certain other embodiments, the compressor is an electric compressor, i.e. a compressor functionally driven by specific means dependent on an electrical energy source. According to these embodiments, the electric compressor is an electric compressor of an electric or hybrid vehicle.

[0018] According to the invention, the main heat transfer fluid reservoir is inserted into the two-phase loop, that is to say that the main reservoir forms a part of the two-phase loop and comprises at least one heat transfer fluid inlet circulating in the two-phase loop and at least one heat transfer fluid outlet opening into the two-phase loop.

[0019] According to certain embodiments, the air conditioning system comprises an evaporator capable of extracting thermal energy from a fluid to be cooled. The evaporator can be of any type. The evaporator is in particular adapted to be able to extract heat energy from a gaseous fluid and cool it due to the evaporation of the heat transfer fluid, in particular to be able to extract heat energy from a gaseous fluid - in particular atmospheric air - and cool it before the introduction of the cooled gaseous fluid into at least one part of the passenger compartment of the motor vehicle. The evaporator can also extract calories from the fluid which cools the battery, or directly extract calories from the battery by direct or indirect contact of the refrigerant with the battery.

[0020] According to certain embodiments, the air conditioning system comprises a condenser capable of supplying thermal energy to a fluid. The condenser can be of any type. The condenser is in particular adapted to be able to supply heat energy to a fluid and to heat it due to the condensation / compression of the heat transfer fluid, in particular to be able to supply heat energy to a fluid and to heat it before the introduction of this heated fluid to one of the components of the motor vehicle requiring such a hot fluid, for example the battery or the passenger compartment of the vehicle.

[0021] According to certain embodiments, said auxiliary tank is connected in sealed heat transfer fluid communication to the main tank. According to certain embodiments, said auxiliary tank is connected in sealed heat transfer fluid communication to the lower part of the main tank.

[0022] According to certain embodiments, said auxiliary tank is connected in sealed communication of heat transfer fluid to the main tank by a conduit opening in the lower part of said auxiliary tank. According to certain advantageous embodiments, said auxiliary tank is connected in sealed communication of heat transfer fluid to the main tank by a conduit opening in the lower part of said main tank. According to these embodiments, the heat transfer fluid circulating from said auxiliary tank to the main tank is heat transfer fluid in the liquid state.

[0023] According to certain embodiments, the conduit opening into the lower part of the main tank has a valve for controlling a flow rate of heat transfer fluid in the conduit.

[0024] The heating member for the heat transfer fluid contained in said auxiliary tank may be of any type provided that it allows heating of the heat transfer fluid contained in said auxiliary tank to a temperature sufficient for the heat transfer fluid contained in said auxiliary tank to reach a pressure value greater than the pressure of the heat transfer fluid in the main tank. The heating member heating of the heat transfer fluid contained in said auxiliary tank may be formed of a secondary circuit for heating a second heat transfer fluid arranged to be able to exchange heat with the heat transfer fluid contained in said auxiliary tank. Preferably, the heating member comprises a tube carrying the second heat transfer fluid and forming a coil arranged opposite an external face of said auxiliary tank. However, nothing prevents the provision of such a tube plunging into the heat transfer fluid contained in said auxiliary tank, by providing sealed passages of the tube in said auxiliary tank.

[0025] According to certain embodiments, the heating member for the heat transfer fluid contained in said auxiliary tank is a Joule effect heating member. Preferably, the heating member comprises a resistive member arranged opposite an external face of said auxiliary tank. According to certain advantageous embodiments, the heating member for the heat transfer fluid contained in said auxiliary tank may be a heating member comprising a resistive member - in particular a resistive member made of at least one ceramic material - whose resistance to the conduction of an electric current increases with the temperature. According to certain of these advantageous embodiments, the heating member for the heat transfer fluid contained in said auxiliary tank is a heating member comprising a PTC (Positive Temperature Coefficient) thermistor. The heating range is thus limited and the heating of said auxiliary tank is thus secured.

[0026] According to certain embodiments, the air conditioning system comprises an electronic device configured to be able to receive data provided by a member for measuring the level of heat transfer fluid in the liquid state in the main tank.

[0027] According to certain embodiments, the air conditioning system comprises means for controlling by the electronic device at least one - in particular each - of the compressor, the expansion valve and a valve for controlling the flow rate of heat transfer fluid in the conduit.

[0028] The invention also extends to a method for automatically topping up the heat transfer fluid of an air conditioning system according to the invention, in which, when a heat transfer fluid level measured in the main tank of the air conditioning system corresponds to a measured level value lower than a predetermined minimum value, heat transfer fluid is transferred into the main tank from said top-up tank by heating the heat transfer fluid contained in said top-up tank to a temperature higher than the vaporization temperature of the heat transfer fluid, whereby the pressure of the heat transfer fluid in said top-up tank reaches a pressure value higher than the heat transfer fluid pressure in the two-phase loop, and heat transfer fluid is transferred into the main tank from said booster tank due to this increase in pressure.

[0029] In certain preferred embodiments of a method according to the invention, heat transfer fluid is transferred into the main tank from said auxiliary tank when the pressure of the heat transfer fluid in the main tank is between about 8 bars and about 15 bars. In some of these preferred embodiments, heat transfer fluid is transferred into the main tank from said auxiliary tank when the air conditioning system is at rest.

[0030] The invention also extends to a motor vehicle equipped with an air conditioning system according to the invention. According to the invention, the heat transfer fluid level of the air conditioning system is detected and adjusted automatically as soon as the detected level is lower than a predetermined level limit value. Any intervention that must be carried out by personnel is thus avoided, since the heat transfer fluid is potentially flammable. Brief description of the drawings

[0031] Other characteristics and advantages of the invention will become apparent from reading the description which follows. This is purely illustrative and must be read in conjunction with the appended drawings in which:

[0032] [Fig-1] [Fig.l] is a schematic representation of an air conditioning system known from the prior art, and

[0033] [Fig.2] [Fig.2] is a schematic representation of an air conditioning system according to the invention. Description of the embodiments

[0034] The description below and the figures are given as a non-limiting illustration of a particular embodiment of the invention.

[0035] It is known that in a two-phase evaporation / condensation loop of an air conditioning system, the level of the heat transfer fluid in the main tank varies in particular as a function of the level of demand on the air conditioning system, for example the intensity of the refrigeration requested by the user of the vehicle or by an occupant of a dwelling equipped with such an air conditioning system.

[0036] As this is a variation in the level of heat transfer fluid in the main tank as a function of the level of demand on the air conditioning system, it is customary to determine the minimum level (h-) of heat transfer fluid in the main tank of the vehicle in new condition in operation. To this minimum level (h-), a coefficient a (a< 1) is applied, making it possible to determine a minimum threshold level (Hmini= a.(h-)) in below which it is imperative to inject liquid heat transfer fluid into the air conditioning system from said booster tank.

[0037] Typically, the value of the minimum (h-) level can be determined according to different methods, for example: - by carrying out preliminary tests on a vehicle under various operating conditions of the air conditioning system, in particular taking into account the vehicle's parking conditions, acceleration and deceleration modes, or - by an automatic procedure managed by an electronic device for calculating the air conditioning system which measures - by means of a heat transfer fluid level measuring device associated with the main tank - and records the minimum level (h-) of the heat transfer fluid during operation of the air conditioning system of the vehicle in a substantially new condition (i.e., for example, between 2 and 12 months of driving) and calculates the average value of the values ​​measured and recorded at the end of the driving period in question.

[0038] After the period of evaluation of the average value of the minimum level (h-) of heat transfer fluid, the electronic calculation device 8 receives, from the member 14 for measuring the level of heat transfer fluid 7 associated with the main tank 4 at regular intervals, in particular continuously, at least one piece of data - in particular digital data - representative of the level of heat transfer fluid 7 in the liquid state in the main tank 4.The electronic calculation device 8 compares the measured level of heat transfer fluid 7 in the liquid state in the main tank 4 and the minimum threshold level value (Hmini) and provides a command to a heating member 16 of said auxiliary tank 11 to heat the heat transfer fluid of said auxiliary tank 11 to a temperature at least equal to the vaporization temperature of the heat transfer fluid, when the measured level of heat transfer fluid in the liquid state in the main tank is lower than the minimum threshold level value (Hmini). Typically, the heating member 16 of said auxiliary tank 11 is an electrical heating member 16 by Joule effect connected to a source of electrical energy - in particular an electrical energy generator 17 - under the control of a switch 18 controlled by the electronic calculation device 8.

[0039] An air conditioning system 1' known from the prior art is shown in [Fig.l] described in the introductory part of this text.

[0040] A two-phase loop 15 with automatic leveling of heat transfer fluid 7 of an air conditioning system 1 according to the invention is shown schematically in [Fig.2]. The two-phase loop 15 provides a circuit of heat transfer fluid 7 circulating in the two-phase loop 15 in which it undergoes a succession of phases of vaporization (from liquid to vapor) and condensation (from vapor to liquid). The heat transfer fluid may be a conventional heat transfer fluid, for example a heat transfer fluid of the R1234yf type. The circuit formed by the two-phase loop 15 comprises a compressor 2 which may be a mechanical compressor or an electric compressor and in which heat transfer fluid 7 in the gaseous state circulates and undergoes a compression phase by which the heat transfer fluid 7 heats up. Downstream of the compressor 2 (depending on the direction of circulation of the heat transfer fluid 7 in the two-phase loop 15), the two-phase loop 15 comprises a condenser 3 in which heat transfer fluid 7 in the compressed and hot gaseous state circulates and liquefies by giving up heat energy to a fluid 10 which heats up due to this exchange. Downstream of the condenser 3, the two-phase loop 15 and the part 19 of the two-phase loop 15 in which the compressed heat transfer fluid 7 is essentially in the liquid state comprise a main reservoir 4 of compressed liquid heat transfer fluid 7.The condenser 3 marks the upstream limit of the part 19 of the two-phase loop 15 in which the compressed heat transfer fluid 7 is essentially in the liquid state. The main heat transfer fluid 7 reservoir 4 has an inlet 20 for compressed liquid heat transfer fluid and an outlet 21 for compressed liquid heat transfer fluid flowing towards an expansion valve 5. The heat transfer fluid outlet 21 is arranged so as to allow a flow of liquid heat transfer fluid 7 towards the expansion valve 5.

[0041] The main tank 4 comprises a member 14 for measuring the level of liquid heat transfer fluid 7 in the main tank 4. The member 14 for measuring the level of liquid heat transfer fluid 7 is in functional connection with an electronic device 8 capable of receiving data representative of the level of heat transfer fluid 7 in the main tank, provided by the measuring member 14. The main tank 4 also comprises means for filtering impurities and capturing moisture likely to pollute the heat transfer fluid 7. The main tank 4 also has a second inlet 22 for heat transfer fluid in the main tank 4. This second inlet 22 is in fluid communication with a conduit 12 adapted to put the main tank 4 in heat transfer fluid 7 communication with a make-up tank 11 containing heat transfer fluid 7.The conduit 12 is provided with a valve 13 adapted to, in a first state - in particular a first position - of the valve 13, allow a transfer of heat transfer fluid 7 into the main tank 4 from said auxiliary tank 11, and in a second state - in particular a second position - of the valve 13 to oppose any transfer of heat transfer fluid 7 into the main tank 4 from said auxiliary tank 11. The state (open / closed) of the valve 13 is controlled by the electronic calculation device 8. The second inlet 22 of heat transfer fluid 7 into the main tank 4 forms one of the longitudinal ends of the conduit 12, the other longitudinal end of the conduit 12 being in fluid communication with an outlet 23 of heat transfer fluid 7. of the auxiliary tank 11. Advantageously, the outlet 23 of heat transfer fluid 7 is positioned in the lower part of said auxiliary tank 11 so that the heat transfer fluid 7 capable of being transferred into the main tank 4 from said auxiliary tank 11 is necessarily in the liquid state.

[0042] The air conditioning system 1 according to the invention is provided with a member 16 for heating the heat transfer fluid 7 contained in said auxiliary tank 11. Any heating means suitable for heating a heat transfer fluid 7 may be used. In the embodiment shown, the heating member 16 is a member for heating the heat transfer fluid 7 by the Joule effect. The member 16 for heating the heat transfer fluid 7 contained in said auxiliary tank 11 is a heating member 16 powered by a source 17 of electrical energy - in particular an electrical energy generator or by a storage battery -. The power supply of the heating member 16 by the source 17 of electrical energy is controlled by a switch 18 controlled by the electronic calculation device 8.The heating member 16 of the heat transfer fluid 7 contained in said auxiliary tank 11 is adapted to bring the heat transfer fluid 7 to a temperature at least equal to its vaporization temperature at the pressure of said auxiliary tank 11, whereby the heat transfer fluid 7 passes into the gaseous state in said auxiliary tank 11 and increases the pressure in said auxiliary tank 11. The heat transfer fluid 7 in the less dense gaseous state floats in said auxiliary tank 11 by pressurizing the heat transfer fluid 7 in the liquid state to a pressure dependent on the heating temperature and chosen to be greater than the pressure of the heat transfer fluid 7 in the part 19 of the two-phase loop 15.When the valve 13 controlled by the electronic calculation device 8 is opened, heat transfer fluid 7 under a pressure greater than the pressure of the heat transfer fluid 7 circulating in the part 19 of the two-phase loop 15 is introduced into the part 19 of the two-phase loop 15, whereby the heat transfer fluid 7 is topped up.

[0043] Downstream of the main tank 4 (still in the direction of circulation of the heat transfer fluid 7 in the two-phase loop 15), the two-phase loop 15 comprises an expander 5 - in particular in the form of an expansion valve 5 - in which the pressure of the heat transfer fluid 7 decreases. The expander 5 marks the downstream limit of the part 19 of the two-phase loop 15 in which the compressed heat transfer fluid 7 is essentially in the liquid state. Downstream of the expander 5, the expanded heat transfer fluid 7 passes through an evaporator 6 in which the expanded heat transfer fluid 7 is evaporated by taking heat energy from a fluid 9 to be cooled, whereby the fluid 9 to be cooled is cooled and then directed towards the passenger compartment of the motor vehicle for air conditioning purposes, the cooled fluid can also be used to cool the battery. Downstream of the evaporator 6, the heat transfer fluid 7 in the gaseous state is guided to the compressor 2 in which it initiates a new cycle of compression, condensation, expansion and evaporation.

[0044] In the embodiment shown, the pressure reducer 5, the compressor 2, the valve 13 for admitting heat transfer fluid 7 into the main tank 4 from said auxiliary tank 11, the switch 18 and the member 14 for measuring the level of heat transfer fluid 7 in the main tank 4 are configured to be able to exchange or transmit or receive data with the electronic calculation device 8.

[0045] The invention allows automatic topping up of heat transfer fluid in a two-phase loop of an air conditioning system and avoids the use of a rotary volumetric pump for increasing the pressure of the main tank, said rotary volumetric pump being expensive and liable to create leaks, in particular due to the rotation of its rotary axis.

[0046] The present invention therefore makes it possible to defer human intervention for adjusting the level of heat transfer fluid 7 in the two-phase loop 15, taking into account the possible flammability of the heat transfer fluid 7. But the present invention also makes it possible to reinforce the sealing of the two-phase loop by deferring the use of a volumetric pump for introducing liquid heat transfer fluid into the two-phase loop at a pressure higher than the pressure of the heat transfer fluid in the two-phase loop. In this respect, such a volumetric pump comprising rotating members driven in rotation by an electric motor is expensive and leads to an increased risk of heat transfer fluid leakage due to these rotating members.

Claims

Claims

1. Air conditioning system (1) of the type with two-phase liquid / vapor heat transfer fluid (7) circulating in a two-phase loop (15) comprising a compressor (2) and an expansion valve (4), the air conditioning system (1) comprising: - a main reservoir (4) of heat transfer fluid (7) inserted in the two-phase loop (15), - a second reservoir, called a backup reservoir (11), connected in sealed communication of heat transfer fluid (7) with a part (19) of the two-phase loop (15) extending downstream of the compressor (2) and upstream of the expansion valve (4),characterized in that said top-up tank (11) is provided with a member (16) for heating the heat transfer fluid (7) contained in said top-up tank (11) and adapted to be able to vaporize at least a portion of the heat transfer fluid (7) in said top-up tank (11) and to be able to bring the pressure of the heat transfer fluid (7) in said top-up tank (11) to a pressure of a value greater than the pressure value of the heat transfer fluid (7) in said part (19) of the two-phase loop (15) and to allow a flow of heat transfer fluid (7) in said part (19) of the two-phase loop (15) from said top-up tank (11).,

2. Air conditioning system (1) according to claim 1, characterized in that it comprises an evaporator (6) capable of extracting thermal energy from a fluid (9) to be cooled.

3. Air conditioning system (1) according to one of claims 1 or 2, characterized in that it comprises a condenser (3) capable of supplying thermal energy to a fluid (10).

4. Air conditioning system (1) according to one of claims 1 to 3, characterized in that said auxiliary tank (11) is connected in sealed communication of heat transfer fluid (7) to the main tank (4).

5. System (1) according to one of claims 1 to 4, characterized in that said auxiliary tank (11) is connected in sealed communication of heat transfer fluid (7) to the main tank (4) by a conduit (12) opening into the lower part of the auxiliary tank (11).

6. System (1) according to claim 5, characterized in that the conduit (12) opening into the lower part of the main reservoir (4) has a valve (13) for controlling the flow of heat transfer fluid (7) in the conduit (12).

7. System (1) according to one of claims 1 to 6, characterized in that the member (16) for heating the heat transfer fluid (7) contained in said additional tank (11) is a member (16) for heating by the Joule effect.

8. System (1) according to one of claims 1 to 7, characterized in that it comprises an electronic device (8) configured to be able to receive data supplied by a member (14) for measuring the level of heat transfer fluid (7) in the liquid state in the main tank (4).

9. System (1) according to claim 8, characterized in that it comprises means of control by the electronic calculation device (8), of at least one - in particular of each - of the compressor (2), of the expander (4) and of a valve (13) for controlling the flow of heat transfer fluid (7) in the conduit (12).

10. A method for automatically topping up the heat transfer fluid (7) of an air conditioning system (1) according to one of claims 1 to 9, wherein, when a level of heat transfer fluid (7) measured in the main tank (4) of the air conditioning system (1) corresponds to a value lower than a predetermined minimum value, heat transfer fluid (7) is transferred into the main tank from said make-up tank (11) by heating the heat transfer fluid (7) contained in said make-up tank (11), whereby the pressure of the heat transfer fluid (7) in said make-up tank (11) reaches a pressure value higher than the pressure of the heat transfer fluid (7) in the two-phase loop (15) and heat transfer liquid (7) is transferred into the main tank (4) from said make-up tank (11).

11. Motor vehicle equipped with an air conditioning system (1) according to one of claims 1 to 9.

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