AUTOMATIC DEVICE FOR LEVELING THE AIR CONDITIONING CIRCUIT OF A MOTOR VEHICLE

Abstract

This device for automatically leveling a liquid in a tank comprises a liquid level sensor in the tank, a top-up tank connected to the tank by a filling valve and a computer adapted to control the filling valve to fill the tank when the level of the liquid in the tank reaches a minimum threshold value, said minimum threshold value being developed from a nominal level and a reduction coefficient. Figure for abstract: Fig 1

Description

Title of the invention: AUTOMATIC DEVICE FOR LEVELING THE AIR CONDITIONING CIRCUIT OF A MOTOR VEHICLE Technical field

[0001] The present invention relates to the field of air conditioning systems, in particular the automation of the upgrading of air conditioning systems of motor vehicles.

[0002] To date, air conditioning systems are subjected to a pressure ranging from four to thirty times atmospheric pressure, depending on the refrigerant used. This continuously pressurized circuit, even at rest, causes refrigerant leaks over time.

[0003] A refill of the refrigerant is often necessary after five years, so the user is forced to contact an after-sales service. A complete draining of the air conditioning system is then carried out and the circuit is refilled with refrigerant.

[0004] To date, the refrigerant generally used is part of the family of per and polyfluoroalkyls, more simply known as PFAS, which could be subject to a ban. Indeed, these synthetic substances have negative repercussions on the environment and health.

[0005] Thus, since propane is not harmful to the planet, it is today the best alternative to this current liquid. However, handling propane is dangerous since it is an explosive fluid when in a gaseous state and at room temperature. The process of draining and filling the refrigerant liquid in the workshop is therefore delicate to implement. Statement of the invention

[0006] The present invention aims to overcome this risk and to propose a device for automatically leveling a refrigerant liquid in an air conditioning system.

[0007] The invention therefore relates to a device for automatically leveling a liquid in a tank, comprising a liquid level sensor in the tank. The device comprises a top-up tank connected to the tank by a filling valve and a computer adapted to control the filling valve to fill the tank when the level of the liquid in the tank reaches a minimum threshold value. This minimum threshold value is developed from a nominal level and a reduction coefficient.

[0008] Advantageously, the nominal level is the normal level of liquid in the tank. when using the air conditioning system in new condition.

[0009] The reducing coefficient is less than 1, preferably greater than 0.1, and more preferably between 0.2 and 0.8.

[0010] Advantageously, the tank is a propane tank of an air conditioning system.

[0011] According to one embodiment, the tank is a propane tank of an air conditioning system of a motor vehicle.

[0012] The invention also relates to a motor vehicle air conditioning system comprising a refrigerant loop, itself comprising a reservoir filled with a refrigerant liquid and an expansion valve coupled to an evaporator capable of vaporizing the liquid extracted from the reservoir, a compressor and a condenser. The system comprises a top-up reservoir connected to the reservoir by a filling valve and a computer adapted to control the filling valve to fill the reservoir when the level of the liquid in the reservoir reaches a minimum threshold value. This minimum threshold value is developed from a nominal level and a reduction coefficient.

[0013] The invention also relates to a method for automatically topping up a liquid in a tank of an air conditioning system as defined above, characterized in that it comprises the following steps: - determination of a nominal level, corresponding to the normal level of liquid in the tank when using the air conditioning system when new, - determination of a minimum threshold value from which the auxiliary tank must supply the tank with refrigerant liquid, said minimum threshold value being developed from the nominal level and a reduction coefficient, - continuous determination of the level of refrigerant liquid present in the tank and control of opening of the filling valve when the determined level is lower than the minimum threshold value, in order to fill the tank with a sufficient dose of refrigerant liquid. Brief description of the drawings

[0014] Other aims, characteristics and advantages of the invention will appear on reading the following description, given solely by way of non-limiting example and made with reference to the appended drawings in which:

[0015] - [Fig.l] is a schematic view of the air conditioning system of a vehicle in car;

[0016] - [Fig.2] schematically represents the tank of the air conditioning system at time of the step of determining the nominal level corresponding to the normal level of liquid in the tank when the tank is first correctly filled;

[0017] - [Fig.3] schematically represents the reservoir of the air conditioning system at time of the step of determining the minimum threshold value from which the booster tank must supply the tank with refrigerant liquid; and

[0018] - [Fig.4] schematically represents the reservoir of the air conditioning system when the refrigerant level is below the minimum threshold value. Detailed description

[0019] In [Fig. 1], the general structure of a device 1 for automatically leveling the refrigerant liquid in the reservoir of an air conditioning system of a motor vehicle is shown, according to one embodiment.

[0020] This device 1 comprises a high pressure part A and a low pressure part B.

[0021] The high pressure part A of the device 1 comprises a compressor 2, a condenser 3 and a reservoir 4 filled with a refrigerant liquid 5, while the low pressure part B of the device 1 comprises an expansion valve 6, an evaporator 7, and a pipe between the evaporator 7 and the compressor 2.

[0022] A top-up tank 8 filled with the same refrigerant liquid 5 is connected to the bottom of the tank 4 via a pipe 9. A filling valve 10 is located on the pipe 9 allowing, when it is opened, the tank 4 to be filled.

[0023] According to one embodiment, the refrigerant liquid filling the main tank 4 and the auxiliary tank 8 is propane. Of course, it is not outside the scope of the invention when another type of refrigerant liquid is used.

[0024] The tank 4 comprises a sensor 11 for the level of refrigerant liquid 5 making it possible to continuously obtain the height of the refrigerant liquid 5 present in the tank 4.

[0025] A computer 12 is integrated into the circuit to control the main components and in particular the compressor 2, the expansion valve 6, the filling valve 10, and the sensor 11.

[0026] The refrigerant fluid 5 which circulates in the circuit varies between the liquid and gaseous states. In the gaseous state, the refrigerant fluid 5 passes through the compressor which raises its pressure and compresses it towards the condenser 3. The latter cools the refrigerant 5 in the gaseous state by condensing it. Still under pressure, the refrigerant liquid 5 then passes through the reservoir 4 which filters it, dehydrates it and reinjects it into the air conditioning system, towards the expansion valve 6. This valve 6 is connected to the inlet and outlet of the evaporator 7 and adjusts the quantity of liquid to be supplied to the evaporator. At the outlet of the evaporator 7, the refrigerant fluid 5 is gaseous, cold and at low pressure. It then returns to the compressor 2 which compresses it again and ensures its circulation in the air conditioning system.

[0027] During this process, and during the lifetime of the vehicle, there are leaks of the refrigerant liquid 5. The top-up tank 8 therefore makes it possible to overcome this problem by injecting a sufficient dose of refrigerant liquid 5 into the tank 4.

[0028] The method of injecting refrigerant liquid into the tank 4 comprises three stages.

[0029] The first step is illustrated in [Fig.2] which represents the reservoir 4 of a device 1 for automatically leveling the refrigerant liquid 5 of an air conditioning system of a motor vehicle, during the first step.

[0030] When the vehicle is new and a first dose of refrigerant liquid 5 is injected into the air conditioning system, the level of liquid detected by the sensor 11 in the reservoir 4 varies between a high level h+ and a low level h-, called the nominal level. The difference d between the high level h+ and the low level h- is due to the circulation cycles of the refrigerant liquid in the air conditioning system of the motor vehicle.

[0031] The first step of the method therefore consists of determining the nominal level h- corresponding to the lowest normal level during the first use of the vehicle in new condition, or the first uses not causing a significant variation in the level of the liquid. For this, the sensor observes the level of refrigerant liquid 5 in the tank 4 over several days, several weeks or several months and deduces a nominal level h- therefrom.

[0032] With reference to [Fig.3], during the second step, once the nominal level h- has been determined, the computer 12 determines the minimum threshold value Hmini which represents the minimum level of refrigerant liquid that the air conditioning system needs to operate properly. To do this, the computer factors h- with a reducing coefficient a, according to the following equation:

[0033] Hmini = a*(h-)

[0034] in which a is less than 1, preferably greater than 0.1 and, ideally, between 0.2 and 0.8.

[0035] Once the minimum threshold value Hmini is calculated, the sensor 11 knows the minimum level of refrigerant liquid 5 that the tank 4 can contain.

[0036] The third step consists of continuous monitoring by the sensor 11 of the level of refrigerant liquid 5 over time. This thus makes it possible to permanently know the quantity of liquid 5 present in the tank 4. In [Fig.4], an example is shown in which the level of refrigerant liquid is lower than the minimum threshold value.,.

[0037] When the sensor 11 detects such a situation in which at a time t the level of refrigerant liquid is lower than the minimum threshold value, as shown in [Fig.4], it continues to observe the level of refrigerant liquid 5 over several hours or several days before arriving at a final result. This waiting time allows us to be certain that it is a lack of liquid 5 and not a calculation error which could be due, for example, to a particular position of the car at time t.

[0038] Once the sensor is certain that there is a lack of refrigerant liquid 5 in the tank 4, the computer 12 sends the order to the filling valve 10 to open. Thus, the top-up tank 8 injects refrigerant liquid 5 into the tank 4 up to the nominal level h-. When the level h- is reached, the sensor 11 sends a signal to the computer 12 which gives the order to the filling valve 10 to close.

[0039] Thus, the tank 4 is again filled with the refrigerant liquid 5 necessary for the proper functioning of the air conditioning system.

[0040] It is therefore not necessary, thanks to the invention, to carry out maintenance operations requiring dangerous handling of the coolant.

Claims

Claims

1. Device (1) for automatically leveling a liquid (5) in a tank (4), comprising a sensor (11) for the level of liquid (5) in the tank (4), characterized in that it comprises a top-up tank (8) connected to the tank (4) by a filling valve (10) and a computer (12) adapted to control the filling valve (10) to fill the tank (4) when the level of the liquid (5) in the tank (4) reaches a minimum threshold value (Hmini), said minimum threshold value (Hmini) being developed from a nominal level (h-) and a reduction coefficient.

2. Device (1) according to claim 1, wherein the nominal level (h-) is the normal level of liquid (5) in the reservoir (4) when using the air conditioning system in new condition.

3. Device (1) according to one of claims 1 and 2, in which the reducing coefficient is less than 1, preferably greater than 0.1, more preferably between 0.2 and 0.

8.

4. Device (1) according to any one of claims 1 to 3, wherein the tank (4) is a propane tank of an air conditioning system.

5. Device (1) according to any one of claims 1 to 4, in which the tank (4) is a propane tank of an air conditioning system of a motor vehicle.

6. Motor vehicle air conditioning system comprising a refrigerant loop comprising a reservoir (4) filled with a refrigerant liquid (5) and an expansion valve (6) coupled to an evaporator (7) capable of vaporizing the liquid (5) extracted from the reservoir (4), a compressor (2) and a condenser (3), characterized in that it comprises a top-up reservoir (8) connected to the reservoir (4) by a filling valve (10) and a computer (12) adapted to control the filling valve (10) to fill the reservoir (4) when the level of the liquid (5) in the reservoir (4) reaches a minimum threshold value (Hmini), said minimum threshold value (Hmini) being developed from a nominal level (h-) and a reduction coefficient.

7. Method for automatically leveling a liquid (5) in a tank (4) by means of a device (1) for automatically leveling a liquid (5) according to any one of claims 1 to 5, characterized in that it comprises the following steps: determining a nominal level (h-), corresponding to the normal level of liquid (5) in the tank (4) when using an air conditioning system in new condition, according to claim 6, determining a minimum threshold value (Hmini) from which the auxiliary tank (8) must supply the tank (4) with refrigerant liquid (5), said minimum threshold value (Hmini) being developed from the nominal level (h-) and a reduction coefficient, continuously determining the level of refrigerant liquid (5) present in the tank (4) and controlling the opening of the filling valve (10) when the determined level is lower than the minimum threshold value (Hmini), in order to fill the tank (4) with a sufficient dose of refrigerant liquid (5).

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