A METHOD FOR TESTING THE STATE OF AT LEAST ONE INTERNAL REINFORCEMENT ELEMENT OF A LIQUID TANK OF A VEHICLE

Abstract

A method tests the state of an internal reinforcement element connecting two opposed walls of a liquid tank including an initial amount of liquid measurable by a level sensor. The method includes: determining a first threshold based on the initial amount of liquid and an initial internal pressure of the liquid tank; monitoring a level sensor output and a pressure sensor output; if the pressure sensor output is above the first threshold, determining a second threshold and a third threshold; comparing the level sensor output to the second and third thresholds; if the level sensor output is above the second threshold, sending a first predetermined signal indicating that the internal reinforcement element is broken, and/or if the level sensor output is below a third threshold, sending a second predetermined signal indicating that the internal reinforcement element is broken.

Claims

1. A method for testing the state of at least one internal reinforcement element of a liquid tank of a vehicle, said at least one internal reinforcement element connecting at least two opposed walls of the liquid tank, the liquid tank comprising at least an initial amount of liquid measurable by a level sensor, the method comprising: a) determining a first threshold based on the initial amount of liquid measured by the level sensor and an initial internal pressure of the liquid tank measured by a pressure sensor; b) monitoring a level sensor output and a pressure sensor output; c) if the pressure sensor output is above the first pressure threshold, determining a second level threshold and a third level threshold as a function of the pressure sensor output, the initial level sensor output and the initial internal pressure sensor output; d) comparing the level sensor output to the second and third level thresholds; e) if the level sensor output is above the second level threshold, sending a first predetermined signal indicating that at least one internal reinforcement element connecting the opposed walls is or may be broken, and/or if the level sensor output is below a third level threshold, sending a second predetermined signal indicating that at least one internal reinforcement element connecting the opposed walls is or may be broken.

2. The method according to claim 1, wherein, during step c), the determination of the second and third thresholds is done also as a function of a temperature of the liquid in the tank.

3. The method according to claim 1, comprising incrementing a counter if the level sensor output is between the second threshold and the third threshold.

4. The method according to claim 3, wherein, if the counter (9) is below a fourth predetermined threshold, at least the steps a), b) and c) are performed again, preferably with a plurality of first thresholds.

5. The method according to claim 4, wherein, if the counter is above the fourth threshold, the method comprises sending a signal indicating that at least one internal reinforcement element connecting the opposed walls is not broken.

6. The method according to claim 1, wherein the monitoring step b) relies on an increase or a decrease of pressure inside the tank generated solely by an increase or a decrease of an external tank temperature.

7. The method according to claim 1, wherein the monitoring step b) comprises commanding means for increasing or decreasing pressure inside the tank, preferably in response to a signal from a vehicle crash sensor.

8. The method according to claim 7, wherein the commanding means for increasing or decreasing pressure inside the tank is performed by: using an external pump not forming part of the vehicle; using a means forming part of the vehicle, for example a pump or a heater, and/or commanding a release of the internal tank pressure using a valve of the tank.

9. The method according to claim 1, wherein the method is performed when a power of the vehicle is off, preferably only when a power of the vehicle is off.

10. The method according to claim 1, wherein the method is triggered when the vehicle is in a service mode.

11. The method according to claim 1, wherein a leak detection step is performed before step a).

12. (canceled)

13. A vehicle liquid tank comprising control means configured to implement the method of claim 1.

14. A vehicle comprising a liquid tank and control means configured to implement the method of claim 1.

15. A computer-readable medium comprising instructions which, when executed by a computer, cause the computer to carry out the steps of the method according to claim 1.

Description

[0067] The above and other characteristics, features and advantages of the present invention will become apparent from the following detailed description, taken in conjunction with the accompanying drawings, which illustrate, by way of examples, the principles of the invention. The reference figures quoted below refer to the attached drawings wherein:

[0068] FIG. 1 is a schematic view of one embodiment of a tank which may be used for implementing a method according to the invention;

[0069] FIG. 2 is a schematic view of another embodiment of a tank which may be used for implementing a method according to the invention;

[0070] FIG. 3 is a flowchart showing a first embodiment of a method according to the invention;

[0071] FIG. 4 is a flowchart showing a second embodiment of a method according to the invention; and

[0072] FIG. 5 is a flowchart showing a third embodiment of a method according to the invention.

[0073] The present invention will be described with respect to particular embodiments and with reference to certain drawings but the invention is not limited thereto.

First Embodiment (FIGS. 1 and 3)

[0074] The first embodiment describes a method for testing a state of at least one internal reinforcement element 1 of a liquid tank 2 of a vehicle wherein the internal reinforcement element 1 connects at least two opposed walls of the liquid tank 2, preferably the bottom and the top walls 3, 4. For example, the reinforcement element 1 is a pillar.

[0075] The tank 2 has a level sensor 5 for measuring a level of liquid 6 inside the tank 2.

[0076] The tank 2 has a pressure sensor 7 for measuring an internal pressure of the tank 2.

[0077] The tank 2 is associated to control means 8 which are able to process the data provided by the level sensor 5 and the pressure sensor 7 and to command the steps of the method.

[0078] The tank 2 comprises at least an initial amount of liquid 6 measurable by the level sensor 5. For example, the tank 2 comprises at least 2 mL of liquid 6, for example 20 L of liquid 6. A first threshold is determined by the control means 8 based on the initial amount of liquid 6 measured by the level sensor 5 and an initial internal pressure of the liquid tank 2 measured by a pressure sensor 7 (step a, not shown). For example, the first threshold may be determined using a bi-dimensional lookup table using the initial internal pressure and the initial amount of liquid as input data.

[0079] The method is triggered by an operator when the vehicle is in a service mode and the power of the vehicle is off. After the method has been triggered, a pressure inside the tank is increased by external means, for example by an external pump, inducing an overpressure inside the tank. Of course, it may be provided that a pressure inside the tank is increased using other means, such as means forming part of the vehicle. One or multiple steps of increase of pressure are possible, as well as a progressive increase of pressure (pressure ramp). In another embodiment, it may be provided that a decrease in pressure, inducing a depression inside the tank, is used. For example, such a depression may be induced by an external pump.

[0080] The pressure and the liquid level are monitored by the control means with the sensors (step b) until a tank pressure measured by the pressure sensor 7 is above the first threshold.

[0081] If the pressure sensor 7 output is above the first threshold, a second threshold and a third threshold are determined by the control means 8 as a function of the pressure sensor 7 output, the initial level sensor 5 output and the initial internal pressure sensor 7 output (step c, not shown). For example, the second and third thresholds may be determined using a tri-dimensional lookup table using the pressure sensor 7 output, the initial level sensor 5 output and the initial internal pressure sensor 7 output as input data. It may be provided that the lookup table comprises a fourth dimension consisting in the temperature of the liquid in the tank. As mentioned above, it is thus possible to take into account the thermal expansion of the liquid.

[0082] Then, the level sensor 5 output is compared by the control means 8 to the second and third thresholds to see if the level sensor 5 output is different from an expected level value (step d).

[0083] If the level sensor 5 output is above the second threshold, this could indicate that the internal reinforcement element 1 (or at least one of the internal reinforcement element 1) is broken. Thus, a signal indicating that at least one internal reinforcement element 1 is or may be broken is sent (step e). Preferably, the signal is sent to the driver in a first time. The signal may be a visual signal, for example the signal may consists in a light or a message displayed on the dashboard. The signal, which corresponds to a diagnostic, may be stored on a storage medium to alert an operator of a garage during internal electrical check of the car.

[0084] If the level sensor output is below the third threshold, this could indicate that the internal reinforcement element 1 (or at least one of the internal reinforcement element 1) is broken. Thus, a signal indicating that at least one of the internal reinforcement element is or may be broken is sent.

[0085] If the level sensor 5 output is below the second threshold and above the third threshold, this could indicate that the pillar 1 is intact. Thus, it may be provided that a signal indicating that the internal reinforcement element 1 (or at least one internal reinforcement element 1) is intact is sent.

Second Embodiment (FIGS. 2 and 4)

[0086] In this embodiment, the method is also for testing a state of at least one internal reinforcement element 1 of a liquid tank 2 of a vehicle wherein the internal reinforcement element 1 connects at least two opposed walls of the liquid tank, preferably the bottom 3 and the top 4 walls. For example, at least one reinforcement element is a pillar.

[0087] The tank 2 may for example be identical to the one presented above in relation to the first embodiment.

[0088] A first step of the method consists in performing a leak detection method. In the present case, the leak detection method used is an active leak detection method. Of course, it is provided that any suitable leak detection method may be used, for example the leak detection methods described in WO 2018/002054 or WO 2013/164463, the content of which is herein incorporated by reference.

[0089] If the result of the leak detection method indicates that a leak may exist, then a predetermined signal indicating that at least one internal reinforcement element 1 is or may be broken is sent by the control means 8. Indeed, this result may be a false positive result which in fact is due to a broken internal reinforcement element 1. An operator may subsequently perform further investigations in order to validate or invalidate the existence of a leak in the tank. If a leak appears not to be present, then there is a high probability that the leak detection result is due to a broken reinforcement element.

[0090] If the result of the leak detection method indicates that there is no leak in the tank 2, then a counter 9, for example a predetermined counter 9 of the control means 8, is reset and a state of the vehicle is observed.

[0091] The tank 2 comprises at least an initial amount of liquid 6 measurable by a level sensor 5. For example, the tank comprises at least 2 mL of liquid 6, for example 20 L of liquid 6. A first threshold is determined by the control means 8 based on the initial amount of liquid 6 measured by the level sensor 5 and an initial internal pressure of the liquid tank 2 measured by a pressure sensor 7 (step a, not shown). For example, the first threshold may be determined using a bi-dimensional lookup table using the initial internal pressure and the initial amount of liquid as input data.

[0092] If a power of the vehicle is on, a valve or a pump 10 is activated in order to release pressure from the inside of the tank 2 and the method may be carried out again from the leak detection step. The valve is for example a FTIV or an E-valve. If the power of the vehicle is off, then the control means 8 command an increase of a pressure inside the tank using, for example, means forming part of the vehicle such as an on-board pump. This results in an overpressure inside the tank 2. One or multiple increases of pressure steps are possible, as well as a progressive increase of pressure (pressure ramp). In another embodiment, it may be provided that a decrease of pressure, inducing a depression inside the tank 2, is used. For example, such a depression may be induced by an on-board pump.

[0093] The pressure and the liquid level are monitored by the control means 8 and the sensors 5, 7(step b) until a tank pressure measured by the pressure sensor 7 is above the first threshold.

[0094] If the control means 8 determines that the pressure sensor 7 output is above the first threshold, a second threshold and a third threshold are determined by the control means 8 as a function of the pressure sensor 7 output, the initial level sensor 5 output and the initial internal pressure sensor 7 output (step c, not shown). For example, the second and third thresholds may be determined using a tri-dimensional lookup table using the pressure sensor 7 output, the initial level sensor 5 output and the initial internal pressure sensor 7 output as input data. It may be provided that the lookup table comprises a fourth dimension consisting in the temperature of the liquid in the tank. As mentioned above, it is thus possible to take into account the thermal expansion of the liquid.

[0095] Then, the control means 8 compares the level sensor output to the second and third thresholds to see if the level sensor output is different from an expected level value (step d).

[0096] If the level sensor output is above the second threshold, this could indicate that the internal reinforcement element 1 (or at least one of the internal reinforcement element 1) is broken. Thus, a signal indicating that at least one internal reinforcement element 1 is or may be broken is sent (step e).

[0097] If the level sensor 5 output is below the third threshold, this could indicate that the internal reinforcement element 1 (or at least one of the internal reinforcement element 1) is broken. Thus, a signal indicating that at least one internal reinforcement element 1 is or may be broken is sent (step e, not shown).

[0098] If the level sensor 5 output is below the second threshold and above the third threshold, the counter 9 is incremented. If the counter 9 is below a fourth predetermined threshold, at least the steps a), b) and c) of the method are performed again under the command of the control means 8, preferably with a plurality of first thresholds. If the counter 9 is above the fourth threshold, the method comprises a step of sending a signal indicating that at least one internal reinforcement element 1 connecting the opposed walls 3, 4 is not broken.

Third Embodiment (FIGS. 2 and 5)

[0099] The third embodiment is identical to the second embodiment except for the below discussed points.

[0100] In the third embodiment, the leak detection method is not an active leak detection method but a method based on pressure and temperature analysis such as the one described in EP17305638. Furthermore, the leak detection test is performed by the control means 8 in parallel to the testing of the state of at least one internal reinforcement element 1 of the liquid tank 2 of a vehicle. Thus, contrary to the second embodiment, the test is performed even if the leak detection method detects a leak.

[0101] In the third embodiment, there is no step of actively increasing the internal pressure in the tank after observing that the power of the vehicle is off. Instead, the monitoring step b) relies on an increase or a decrease of pressure inside the tank 2 generated solely by an increase or a decrease of an external tank temperature. When the ambient temperature is increased, the pressure inside the tank is increased. When the ambient temperature is decreased, the pressure inside the tank is decreased.

[0102] In the same way as for the second embodiment, the temperature and the liquid level inside the tank 2 are monitored by the control means 8 until the pressure sensor 7 output is above the first threshold and all of the subsequent steps are identical to those of the second embodiment.

[0103] Whilst the principles of the invention have been set out above in connection with specific embodiments, it is to be understood that this description is merely made by way of example and not as a limitation of the scope of the invention which is determined by the appended claims.