MOTOR VEHICLE COMPRISING A LEAK DETECTION COMPUTER FOR AN AIR CONDITIONING CIRCUIT BASED ON THE COMPRESSOR IGNITION STATUS, PROCESS AND PROGRAM BASED ON SUCH A VEHICLE

Abstract

The invention relates to a motor vehicle comprising an air conditioning system which includes a fluid circuit connected to an air conditioning compressor (C), the air conditioning system comprising a pressure sensor disposed at the inlet or outlet of the air conditioning compressor (C), characterized in that the air conditioning system further comprises a means for evaluating the switching on or off of the air conditioning compressor (C), and a computer receiving the pressure measurement from the sensor, and comparing the pressure value to a predetermined critical pressure threshold below which the computer diagnoses a refrigerant leak, the critical pressure threshold depending on whether the air conditioning compressor (C) is switched on or off. The invention also relates to a method and a program based on such a vehicle. Abstract figure: Fig. 1

Description

Title of the invention: MOTOR VEHICLE COMPRISING A LEAK DETECTION COMPUTER FOR AN AIR CONDITIONING CIRCUIT BASED ON THE COMPRESSOR'S IGNITION STATUS, METHOD AND PROGRAM BASED ON SUCH A VEHICLE

[0001] The invention relates to the field of pressure monitoring systems for the air conditioning circuit of motor vehicles.

[0002] On some of the applicant's projects, a function for monitoring the pressure of the air conditioning circuit is currently only carried out by the maintenance department when the user notices that their air conditioning is not working, or during overhauls.

[0003] However, the gases contained in the air conditioning system are polluting to the environment.

[0004] Thus, there is a need to create a function to identify any risk of leakage from the air conditioning circuit in order to protect the environment.

[0005] Patent KR20090089988A describes an air conditioning control system with a measurement of the pressure at the inlet and outlet of an air conditioning compressor by means of a pressure detector upstream of the air conditioning compressor, and another downstream, and a comparison of the two pressures.

[0006] An objective of the present invention is to remedy the defects of the prior art, and in particular to propose a solution for carrying out a more complete on-board diagnostic than in the prior art by limiting the number of equipment required compared to the prior art.

[0007] To achieve this objective, the invention proposes a motor vehicle comprising an air conditioning system which includes a fluid circuit connected to an air conditioning compressor, the air conditioning compressor comprising an inlet and an outlet connected to the fluid circuit, the air conditioning system comprising a pressure sensor disposed at the inlet or outlet of the air conditioning compressor, characterized in that the air conditioning system further comprises a means for evaluating the switching on or off of the air conditioning compressor, and a computer connected to said sensor and to the evaluation means, receiving the pressure measurement from the sensor, and comparing the pressure value to a predetermined critical pressure threshold below which the computer diagnoses that there is a leak of refrigerant fluid, the critical pressure threshold depending on whether the air conditioning compressor is on or off.

[0008] Advantageously, the invention makes it possible to determine if there is a risk of refrigerant leakage from the air conditioning circuit of motor vehicles by means of a pressure sensor in the air conditioning circuit and a function which compares these pressure measurements with calibrated pressure thresholds to have a more accurate diagnosis than in the prior art.

[0009] The gain of this invention is essentially to protect the environment from the risk of pollution with the refrigerant and to detect a failure of the air conditioning circuit before users notice a loss of the air conditioning function (what is safe is the loss of the defogging function which is ensured by the air conditioning circuit).

[0010] Preferably, the calculator determines: - if the pressure value is between a minimum acceptable pressure threshold and a maximum acceptable pressure threshold higher than said critical pressure threshold, and then diagnoses a normal situation; - if the pressure value is above the maximum acceptable pressure threshold for a period exceeding a first threshold period, and then diagnoses a first anomaly; - if the pressure value is between the minimum acceptable pressure threshold and the critical pressure threshold for a period exceeding a second threshold duration, and then diagnoses a second anomaly; or - if the pressure value is below the critical pressure threshold for a period exceeding a third threshold period, and then diagnoses a third anomaly, the minimum acceptable pressure threshold and the maximum acceptable pressure threshold depending on whether the air conditioning compressor is on or off.

[0011] This allows for a diagnosis according to different pressure value situations.

[0012] Preferably, the threshold durations are between 0.5 and 1.5 s, are preferably 1 s.

[0013] This allows sufficient time to determine the diagnosis.

[0014] Preferably, when the air conditioning compressor is off, the maximum acceptable pressure threshold is calibrated between 5.5 and 6.5 bar, preferably at 6 bar; the minimum acceptable pressure threshold is calibrated between 3.5 and 4.5 bar, preferably at 4 bar; the critical pressure threshold is calibrated between 1.5 and 2.5 bar, preferably at 2 bar.

[0015] This makes it possible to determine precisely whether there is a refrigerant leak when the compressor is off.

[0016] Preferably, when the air conditioning compressor is switched on, and the sensor is located at the outlet of the air conditioning compressor, the maximum acceptable pressure threshold is calibrated between 14.5 and 15.5 bar, preferably at 15 bar; the minimum acceptable pressure threshold is calibrated between 11.5 and 12.5 bar, preferably at 12 bar; the critical pressure threshold is calibrated between 6.5 and 7.5 bar, preferably at 7 bar.

[0017] This makes it possible to determine precisely whether there is a refrigerant leak when the compressor is switched on in this sensor configuration.

[0018] Preferably, when the air conditioning compressor is on, and the sensor is located at the inlet of the air conditioning compressor, the maximum acceptable pressure threshold is calibrated between 6.5 and 7.5 bar, preferably at 7 bar; the minimum acceptable pressure threshold is calibrated between 0.5 and 1.5 bar, preferably at 1 bar; the critical pressure threshold is calibrated between 0.25 and 0.75 bar, preferably at 0.5 bar.

[0019] This makes it possible to determine precisely whether there is a refrigerant leak when the compressor is switched on in this sensor configuration.

[0020] Preferably, the computer is connected to a fault signaling means specifically signaling the diagnosed fault.

[0021] This allows for an alert regarding the fluid leak.

[0022] The invention also relates to a method for detecting leaks in a motor vehicle according to the invention, comprising the following steps: - an evaluation step for switching the air conditioning compressor on or off; - a pressure measurement step at the inlet or outlet of the air conditioning compressor; - a step comparing the measured pressure value to a predetermined critical pressure threshold depending on whether the air conditioning compressor is on or off; and - a diagnostic step for a refrigerant leak if the measured pressure value is below the critical pressure threshold.

[0023] Preferably, in the comparison step, the following is determined: - if the pressure value is between a minimum acceptable pressure threshold and a maximum acceptable pressure threshold higher than said critical pressure threshold, then a normal situation is diagnosed; - if the pressure value is above the maximum acceptable pressure threshold for a period exceeding a first threshold period, then a first anomaly is diagnosed; - if the pressure value is between the minimum acceptable pressure threshold and the critical pressure threshold for a period exceeding a second threshold duration, then a second anomaly is diagnosed; or - if the pressure value is below the critical pressure threshold for a period exceeding a third threshold period, then a third anomaly is diagnosed, the minimum acceptable pressure threshold and the maximum acceptable pressure threshold depending on whether the air conditioning compressor is on or off.

[0024] Another object of the invention relates to a computer program comprising program code instructions for executing the steps of the leak detection method according to the invention, when said program is running on a computer.

[0025] The invention will be further detailed by the description of non-limiting embodiments, and on the basis of the attached [Fig.1] which schematically illustrates a fluid circuit and a compressor of an air conditioning system of a motor vehicle according to a preferred embodiment of the invention.

[0026] It is important to monitor leaks in an air conditioning system because the fluids used in air conditioning systems have an impact on the ozone layer and on global warming, hence the importance of this invention. For some refrigerants, the ozone depletion potential (ORP) reaches 0.05 (R22) or even 0.82 (R12) and the global warming potential (GWP) over 100 years reaches 3900 for R404A or even 10900 (R12).

[0027] In the prior art, manufacturers did not know the impact of these refrigerants on the environment, so leaks were not considered important and leaks were only looked for when the user lost their air conditioning.

[0028] Next, manufacturers imposed monitoring of the air conditioning circuit during servicing.

[0029] The next step is the creation of an embedded function that continuously checks the risk of leakage in the air conditioning circuit.

[0030] The creation of this air conditioning circuit pressure monitoring function consists first of all in implanting a pressure sensor D in the air conditioning circuit.

[0031] Regarding the placement of the pressure sensor D in the air conditioning circuit, the choice of the position of sensor D in the circuit is not arbitrary: - either we place the pressure sensor D on the air conditioning circuit at the outlet (downstream) of the air conditioning compressor C; - either we place the pressure sensor D on the air conditioning circuit at the inlet (upstream) of the air conditioning compressor C.

[0032] If the sensor D is positioned at the outlet of the air conditioning compressor C, a pressure sensor D must be fitted which measures pressures in the range [0 bar - 20 bars].

[0033] If the sensor D is positioned at the inlet of the air conditioning compressor C, a pressure sensor D must be fitted which measures pressures in the range [0 bar - 7 bars].

[0034] In the preferred embodiment, the pressure sensor D is located at the inlet (i.e. upstream) of the air conditioning compressor C in order to use a simpler sensor.

[0035] This also shows that the warning thresholds depend on the position of the pressure sensor D in the air conditioning circuit. Thus, the pressure thresholds detailed below are calibrable pressure thresholds, since these pressure thresholds depend on the location of the pressure sensor D on the air conditioning circuit.

[0036] Regarding the dependence of the pressure thresholds, these thresholds depend on several things, which we will list here: - as explained, these pressure thresholds depend on the location of the pressure sensor D relative to the air conditioning compressor C (upstream or downstream of the air conditioning compressor C); - these pressure thresholds depend on the temperature difference between the desired cabin temperature and the outside temperature; - these pressure thresholds also depend on whether the air conditioning compressor C is switched on or off; - these thresholds also depend on the type of refrigerant in the air conditioning system (R 134a, R22, ...)

[0037] Regarding the air conditioning circuit pressure monitoring function itself, in a first step, this function retrieves the status of the air conditioning compressor C: - the air conditioning compressor C is on; or - the air conditioning compressor C is off).

[0038] Indeed, the thresholds will be different between the two states of the air conditioning compressor C.

[0039] This information on the status of the air conditioning compressor C circulates on the vehicle's CAN communication network, so the function can retrieve the information which is continuously emitted as soon as the ignition is switched on at the dashboard by the driver.

[0040] This information is updated at a given frequency on the CAN network, for example every 200 milliseconds (order of magnitude).

[0041] In a second step, as soon as the user turns on the dashboard, the function is operational.

[0042] This function retrieves pressure information from the pressure sensor D installed on the air conditioning circuit at calibrable time intervals during function development. In the preferred embodiment, the function retrieves the pressure information every 400 milliseconds.

[0043] We will call this pressure information: Pclim

[0044] Furthermore, the function compares this Pclim information with the following thresholds: - SminNorm: minimum acceptable pressure threshold; - SmaxNorm: maximum acceptable pressure threshold; - SminFuite: critical pressure threshold, from which there is a certainty of leakage.

[0045] Regarding specifically the conditions monitored by the function, it is verified that the pressure value Pclim is well within the minimum and maximum thresholds (SminNorm and SmaxNorm), if this is the case, the situation is normal and the function continues its monitoring normally.

[0046] If the function identifies that the pressure value Pclim is greater than the maximum threshold SmaxNorm for a duration greater than DI (duration threshold), the situation is abnormal, the function initiates a first reconfiguration.

[0047] If the function identifies that the pressure value Pclim is between the minimum threshold SminNorm and the critical threshold SminFuite for a duration greater than D2 (duration threshold), then the situation is abnormal, the function engages a second reconfiguration.

[0048] If the function identifies that the pressure value Pclim is less than the critical threshold SminFuite for a duration greater than D3 (duration threshold), the situation is abnormal, the function engages the third reconfiguration.

[0049] D1, D2 and D3 are calibrable durations during the development of the air conditioning circuit pressure monitoring function. These three durations can be calibrated independently of each other, but the order of magnitude is 1 second.

[0050] Regarding the calibration of the thresholds SminNorm, SmaxNorm and SminFuite (orders of magnitude), these thresholds depend on the location of the pressure sensor D relative to the air conditioning compressor C.

[0051] If the air conditioning compressor C is off: - the maximum threshold SmaxNorm is calibrated around 6 bars of pressure, during the development of this function; - the minimum threshold SminNorm is calibrated around 4 bars of pressure; and - the leak threshold SminFuite is calibrated around 2 bars of pressure.

[0052] If the air conditioning compressor is switched on and sensor D is located at the outlet of the air conditioning compressor C (downstream): - the maximum threshold SmaxNorm is calibrated around 15 bars of pressure, during the development of this function; - the minimum threshold SminNorm is calibrated around 12 bars of pressure; and - The leak threshold SminFuite is calibrated around 7 bars of pressure.

[0053] If the air conditioning compressor is on and sensor D is located at the inlet of the air conditioning compressor C (upstream): - the maximum threshold SmaxNorm is calibrated around 7 bars of pressure, during the development of this function; - the minimum threshold SminNorm is calibrated around 1 bar of pressure; and - The leak threshold SminFuite is calibrated around 0.5 bar pressure.

[0054] As can be seen, it is not necessary for the air conditioning compressor C to be switched on to identify a leak in the air conditioning circuit; the only condition may be that the vehicle ignition is switched on to supply the computer which carries the function of monitoring the pressure of the air conditioning circuit.

[0055] Regarding the reconfigurations of this function, if the first reconfiguration is initiated, this means that the function raises a fault code, for example Plxx, to indicate to the maintenance service that the air conditioning circuit is over-pressurized and that the air conditioning compressor C needs to be inspected, or even the air conditioning compressor C needs to be changed or the refrigerant F needs to be changed.

[0056] The function lights up a "service" indicator on the dashboard, to signal to the driver the need to go to the maintenance service, to carry out a vehicle inspection.

[0057] If the function engages the second reconfiguration, this means that the function raises a fault code, for example P2xx, to indicate to the maintenance service that the air conditioning circuit is under pressure and therefore not working optimally and that there is a suspicion of a leak in the air conditioning circuit, therefore the need to inspect the air conditioning circuit, or even to change the air conditioning compressor C.

[0058] The function lights up a "service" indicator on the dashboard, to signal to the driver the need to go to the maintenance service, to carry out a vehicle inspection.

[0059] Optionally, a message on the dashboard can light up to indicate "a fault in the air conditioning circuit", for example.

[0060] If the function engages the third reconfiguration, this means that the function raises a fault code, for example P3xx, to indicate to the maintenance service that the air conditioning circuit is no longer operational and that there is a leak in the air conditioning circuit, therefore it is urgent to inspect the air conditioning circuit.

[0061] The function lights up a stop light (“STOP”) on the dashboard, to signal to the driver the need to urgently go to the maintenance service to carry out an inspection of the vehicle, because under these conditions the demister can no longer function and the user has already been warned by the “service” light.

[0062] The function inhibits the operation of the air conditioning compressor C, so as not to further pollute the environment with the refrigerant F which leaks from the circuit.

[0063] Optionally, a message on the dashboard can be illuminated to specify "air conditioning not working and defrosting impossible" for example.

[0064] Regarding the exit from reconfiguration modes, a first possibility is that if the air conditioning circuit pressure monitoring function finds a Pclim pressure value between the minimum and maximum thresholds SMinNorm and SmaxNorm for a minimum duration of DR1, the function inhibits the reconfiguration modes, i.e. that the fault codes Pxxx change from the permanent state to the transient state to indicate to the maintenance service that there was at some point a failure on the air conditioning circuit, but that the problem resolved itself.

[0065] The indicator light goes out, the optional message on the instrument panel goes out, the air conditioning compressor C can resume its normal operation.

[0066] DR1 is calibrable during the function development phase and is preferably calibrated at 2000 milliseconds.

[0067] In a second possibility, after an inspection and / or replacement of the air conditioning circuit component(s), the maintenance service clears the fault code(s), i.e., it repairs the fault and the user can once again have a fully operational vehicle.

[0068] This invention is valid for all vehicles which have an air conditioning system (thermal, hybrid, electric, tractor, truck, motorcycle, airplane etc.).

[0069] The gain of this invention is essentially to protect the environment from the risk of pollution with the refrigerant F and to detect a failure of the air conditioning circuit before users notice a loss of the air conditioning function (what is safe is the loss of the demisting function provided by the air conditioning circuit).

Claims

Demands

1. A motor vehicle comprising an air conditioning system which includes a fluid circuit connected to an air conditioning compressor (C), the air conditioning compressor (C) comprising an inlet (E) and an outlet (S) connected to the fluid circuit, the air conditioning system comprising a pressure sensor (D) disposed at the inlet or outlet of the air conditioning compressor (C), characterized in that the air conditioning system further comprises a means for evaluating the ignition or extinction of the air conditioning compressor (C), and a computer connected to said sensor (D) and to the evaluation means, receiving the pressure measurement from the sensor (D), and comparing the pressure value to a predetermined critical pressure threshold below which the computer diagnoses that there is a refrigerant leak, the critical pressure threshold depending on whether the air conditioning compressor (C) is on or off.

2. Motor vehicle according to claim 1, characterized in that the computer determines: - whether the pressure value is between a minimum acceptable pressure threshold and a maximum acceptable pressure threshold greater than said critical pressure threshold, and then diagnoses a normal situation; - whether the pressure value is greater than the maximum acceptable pressure threshold for a period greater than a first threshold duration, and then diagnoses a first anomaly; - whether the pressure value is between the minimum acceptable pressure threshold and the critical pressure threshold for a period greater than a second threshold duration, and then diagnoses a second anomaly;or - if the pressure value is below the critical pressure threshold for a period exceeding a third threshold period, and then diagnoses a third anomaly, the minimum acceptable pressure threshold and the maximum acceptable pressure threshold depending on whether the air conditioning compressor is on or off (C).

3. Motor vehicle according to claim 2, characterized in that the threshold durations are between 0.5 and 1.5 s, are preferably 1s.

4. Motor vehicle according to any one of claims 2 to 3, characterized in that when the air conditioning compressor (C) is off, the maximum acceptable pressure threshold is calibrated between 5.5 and 6.5 bar, preferably 6 bar; the minimum acceptable pressure threshold is calibrated between 3.5 and 4.5 bar, preferably 4 bar; the critical pressure threshold is calibrated between 1.5 and 2.5 bar, preferably 2 bar.

5. Motor vehicle according to any one of claims 2 to 4, characterized in that when the air conditioning compressor (C) is switched on, and the sensor is disposed at the outlet of the air conditioning compressor (C), the maximum acceptable pressure threshold is calibrated between 14.5 and 15.5 bar, preferably at 15 bar; the minimum acceptable pressure threshold is calibrated between 11.5 and 12.5 bar, preferably at 12 bar; the critical pressure threshold is calibrated between 6.5 and 7.5 bar, preferably at 7 bar.

6. Motor vehicle according to any one of claims 2 to 5, characterized in that when the air conditioning compressor (C) is switched on, and the sensor is disposed at the inlet of the air conditioning compressor (C), the maximum acceptable pressure threshold is calibrated between 6.5 and 7.5 bar, preferably at 7 bar; the minimum acceptable pressure threshold is calibrated between 0.5 and 1.5 bar, preferably at 1 bar; the critical pressure threshold is calibrated between 0.25 and 0.75 bar, preferably at 0.5 bar.

7. Motor vehicle according to any one of claims 2 to 6, characterized in that the computer is connected to a fault signaling means specifically signaling the diagnosed fault.

8. A method for detecting leaks in a motor vehicle according to any one of claims 1 to 7, comprising the following steps: - a step of evaluating the ignition or extinction of the air conditioning compressor (C); - a step of measuring the pressure at the inlet or outlet of the air conditioning compressor (C); - a step of comparing the measured pressure value to a predetermined critical pressure threshold depending on whether the air conditioning compressor (C) is switched on or off; and - a diagnostic step for a refrigerant leak if the measured pressure value is below the critical pressure threshold.

9. A leak detection method according to claim 8, characterized in that in the comparison step, the following is determined: - if the pressure value is between a minimum acceptable pressure threshold and a maximum acceptable pressure threshold higher than said critical pressure threshold, then a normal situation is diagnosed; - if the pressure value is above the maximum acceptable pressure threshold for a period exceeding a first threshold period, then a first anomaly is diagnosed; - if the pressure value is between the minimum acceptable pressure threshold and the critical pressure threshold for a period exceeding a second threshold duration, then a second anomaly is diagnosed; or - if the pressure value is below the critical pressure threshold for a period exceeding a third threshold period, and a third anomaly is then diagnosed, the minimum acceptable pressure threshold and the maximum acceptable pressure threshold depending on whether the air conditioning compressor is on or off (C).

10. Computer program comprising program code instructions for performing the steps of the leak detection method according to any one of claims 8 to 9, when said program is running on a computer.

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