DIAGNOSIS OF THE POSSIBILITY OF USING VEHICLE DIHYDROGEN TANKS

Abstract

A diagnostic method is implemented in a vehicle comprising N tanks storing hydrogen, each equipped with a valve, in each of which the pressure and temperature of the stored hydrogen are measured, and with N ≥ 2. This method comprises a step (10-60) in which, when the valve of a tank is open, a temperature of the stored hydrogen is estimated for the latter using a first table, establishing a correspondence between pressure and density pairs and temperatures, and at least the measured pressure and a current density of the stored hydrogen, and, if the absolute value of a difference between the measured and estimated temperatures of the tank is greater than a chosen threshold, the use of the latter is prohibited. Figure 3

Description

Title of the invention: DIAGNOSIS OF THE POSSIBILITY OF USING DIHYDROGEN TANKS OF A VEHICLE Technical field of the invention

[0001] The invention relates to vehicles comprising at least two di-hydrogen tanks intended to supply a fuel cell, and more precisely to the diagnosis within such vehicles of the possibility of using these tanks. State of the art

[0002] Certain vehicles, possibly of the automobile type, comprise at least two tanks of dihydrogen (or H2) intended to supply a fuel cell responsible for supplying electrical energy to at least one electric motor of their powertrain (or powertrain).

[0003] As is known to those skilled in the art, for safety reasons, a (hydrogen) tank must not be used when the sensor responsible for measuring the temperature of the hydrogen it stores is faulty.

[0004] Currently, the diagnosis of failure of tank temperature sensors is carried out by comparing the measurements of these sensors two by two. Depending on the temperature difference between each pair of sensors and whether or not these differences exceed a chosen temperature threshold, each faulty sensor can be deduced, and the use of the corresponding tank is immediately prohibited.

[0005] Such a type of diagnosis proves well suited to the case where the number of tanks is relatively large. However, the smaller the number of tanks, the more difficult it is to determine which one(s) should no longer be used. This is particularly the case when the number of tanks is equal to two. It will be understood that in case of doubt one may find oneself in a situation where no tank can be used, which then prevents the use of the fuel cell, and therefore may prevent any movement of the vehicle if its powertrain does not also include a thermal motor or if it does not have a rechargeable power battery to supply its electric motor.

[0006] The invention therefore aims in particular to improve the situation. Presentation of the invention

[0007] It proposes in particular for this purpose a diagnostic method intended to be implemented in a vehicle comprising N tanks storing dihydrogen, each equipped with a valve, in each of which pressure and temperature are measured. stored hydrogen, and with N > 2.

[0008] This diagnostic method is characterized by the fact that it comprises a step in which, when the valve of a tank is open, a temperature of the stored hydrogen is estimated for the latter using a first table, establishing a correspondence between pressure and density pairs and temperatures, and at least the measured pressure and a current density of the stored hydrogen, and, if the absolute value of a difference between the measured and estimated temperatures of the tank is greater than a chosen threshold, the use of the latter is prohibited.

[0009] Thanks to the invention, it is now possible to determine with certainty each faulty temperature sensor and therefore each tank that should no longer be used, regardless of the number N (with N > 2) of tanks in the vehicle and independently of the temperatures measured in the other tanks, which eliminates the risk of uncertainty in the decision imposing the prohibition of use of all the N tanks, unless all the N temperature sensors are simultaneously faulty.

[0010] The diagnostic method according to the invention may include other characteristics which may be taken separately or in combination, and in particular:

[0011] - in its step, for each tank having its valve open, we can determine in the first table a first temperature corresponding to the corresponding measured pressure and current density, then a density error can be estimated as a function of a difference between the current density and a density calculated using a formula giving the density as a function of at least this first determined temperature and the measured pressure, then a temperature correction can be estimated as a function of at least this estimated density error, then the temperature can be estimated as a function of the first determined temperature and estimated temperature correction;

[0012] - in the presence of the first option, in its step, for each tank having its valve open, the temperature correction can be estimated using a second table, establishing a correspondence between density errors and temperature corrections, and the estimated density error;

[0013] - in its step, for each tank having its valve open, we can estimate the current density as a function of an estimated current dihydrogen mass;

[0014] - in the presence of the last option, in its step, for each tank having its valve open, we can estimate the mass of hydrogen in progress based on a difference between an initial mass of hydrogen at the opening of this valve and a mass of hydrogen consumed since this opening of the valve;

[0015] - in the presence of the last sub-option, in its step, for each tank having With its valve open, we can estimate the initial mass of dihydrogen as a function of a density calculated using a formula giving the density as a function of at least the measured pressure and an average value of temperatures measured in at least some of the tanks;

[0016] - in its step, the threshold can be between 3°C and 10°C.

[0017] The invention also provides a computer program product comprising a set of instructions which, when executed by processing means, is capable of implementing a diagnostic method of the type presented above, in a vehicle comprising N tanks storing dihydrogen, each equipped with a valve, in each of which the pressure and temperature of the stored dihydrogen are measured, and with N > 2, to diagnose each tank to be prohibited from use.

[0018] The invention also proposes a diagnostic device intended to equip a vehicle comprising N tanks storing dihydrogen, each equipped with a valve, in each of which the pressure and temperature of the stored dihydrogen are measured, and with N > 2.

[0019] This diagnostic device is characterized by the fact that it comprises at least one processor and at least one memory arranged to carry out the operations consisting, when the valve of a tank is open, in estimating for the latter a temperature of the stored hydrogen using a first table, establishing a correspondence between pressure and density pairs and temperatures, and at least the measured pressure and a current density of the stored hydrogen, and, if the absolute value of a difference between the measured and estimated temperatures of the tank is greater than a chosen threshold, in prohibiting the use of the latter.

[0020] The invention also proposes a vehicle, possibly of the automobile type, and comprising, on the one hand, N tanks storing dihydrogen, each equipped with a valve, in each of which the pressure and temperature of the stored dihydrogen are measured, and with N > 2, and, on the other hand, a diagnostic device of the type presented above. Brief description of the figures

[0021] Other characteristics and advantages of the invention will appear on examining the detailed description below, and the appended drawings, in which:

[0022] [Fig. 1] schematically and functionally illustrates an exemplary embodiment of a vehicle comprising a GMP transmission chain with an electric motor associated with a rechargeable power battery and a fuel cell coupled to two hydrogen tanks and associated with a supervision computer, and a diagnostic device according to the invention,

[0023] [Fig.2] schematically and functionally illustrates an exemplary embodiment of a supervision calculator comprising an exemplary embodiment of a device of diagnosis according to the invention,

[0024] [Fig.3] schematically illustrates an example of an algorithm implementing a diagnostic method according to the invention. Detailed description of the invention

[0025] The invention aims in particular to propose a diagnostic method, and an associated diagnostic device DD, intended to enable diagnosis, among N tanks RDn storing dihydrogen (with n = 1 to N and N > 2) and equipping a vehicle V, each tank RDn having to be prohibited from use due to the failure of the associated temperature sensor.

[0026] In the following, it is considered, by way of non-limiting example, that the vehicle V is of the automobile type. It is for example a car, as illustrated in [Fig.l]. But the invention is not limited to this type of vehicle. It in fact concerns any type of vehicle (land, sea (or river), or air) comprising at least two dihydrogen tanks intended to supply a fuel cell responsible for supplying electrical energy to at least one electric motor of the powertrain (or GMP).

[0027] Furthermore, it is considered in the following, by way of non-limiting example, that the vehicle V comprises a transmission chain with a powertrain (or GMP) of the all-electric type (and therefore whose drive is provided exclusively by at least one electric motor MME). But the GMP could be of the hybrid type (thermal and electric).

[0028] [Fig. 1] schematically illustrates an example of an embodiment of a vehicle V comprising a diagnostic device DD according to the invention and an electric GMP transmission chain (and therefore an electric motor MME) associated with a rechargeable power battery BP and a fuel cell PC coupled to two hydrogen tanks RDn. It is important to note that in the example illustrated non-limitingly in [Fig. 1] the vehicle V only comprises two tanks RDn (i.e. n = 1 or 2). But the number N of tanks RDn can take any value greater than or equal to 2 (i.e. n = 1 to N, with N > 2).

[0029] The transmission chain has a GMP which is, here, purely electric and therefore which comprises, in particular, an electric motor MME, a motor shaft, and a transmission shaft. Here, the term "electric motor" means an electric machine arranged so as to provide engine torque to move the vehicle V when it is supplied with electrical energy, as well as possibly to recover torque in the transmission chain.

[0030] The electric motor MME (here an electric motor) is supplied with electrical energy by the rechargeable power battery BP and by a fuel cell fuel PC coupled to N tanks RDn (here N = 2), storing dihydrogen. Furthermore, this electric motor MME is coupled to the motor shaft, to provide it with engine torque by rotational drive, and this motor shaft is here coupled to a reducer RD which is also coupled to the transmission shaft, itself coupled to a first train Tl, preferably via a differential DF.

[0031] This first train T1 is here located in the front part PVV of the vehicle V. Consequently, in this example the wheels RV of the first train T1 are both driving and steering. But in a variant this first train T1 could be the one which is here referenced T2 and which is located in the rear part PRV of the vehicle V, and in this case the (front) wheels RV are only steering (the rear wheels of the second rear train T2 then being at least driving and also possibly steering).

[0032] The power battery BP and the fuel cell PC are also responsible for supplying an on-board network (not shown) which is an electrical power supply network to which electrical (or electronic) equipment (or components) that consume electrical energy are coupled.

[0033] For example, the power (or main or traction) battery BP may comprise electrical energy storage cells, possibly electrochemical (for example of the lithium-ion (or Li-ion) or Ni-Mh or Ni-Cd type). Also for example, the power battery BP may be of the low voltage type (typically 450 V for illustration purposes). But it could be of the medium voltage or high voltage type.

[0034] It is recalled that the fuel cell is an electrochemical generator which produces an electrical voltage by oxidation of reducing fuel (here dihydrogen) on one electrode coupled with the reduction on another electrode of an oxidant, such as oxygen from the air.

[0035] Although this does not appear in [Fig.l], access to each tank RDn is controlled by a valve whose open or closed state is controlled by a supervision computer CS according to requirements. In addition, each tank RDn is associated with a temperature sensor, responsible for measuring the temperature thmn of the hydrogen it stores, and a pressure sensor, responsible for measuring the pressure phmn of the hydrogen it stores.

[0036] As mentioned above, the invention proposes in particular a diagnostic method intended to make it possible to diagnose, among the N RDn tanks, each RDn tank which must be prohibited from use due to the failure of the associated temperature sensor.

[0037] This (diagnostic) method can be implemented at least partially by the diagnostic device DD (illustrated at least partially in Figures 1 and 2) which comprises for this purpose at least one processor PR1, for example a digital signal processor (or DSP ("Digital Signal Processor")), and at least one MD memory. This DD diagnostic device can therefore be produced in the form of a combination of electrical or electronic circuits or components (or "hardware") and software modules (or "software"). For example, it can be a microcontroller.

[0038] The memory MD is live in order to store instructions for the implementation by the processor PR1 of at least part of the diagnostic method. The processor PR1 may comprise integrated (or printed) circuits, or several integrated (or printed) circuits connected by wired or wireless connections. An integrated (or printed) circuit is understood to mean any type of device capable of carrying out at least one electrical or electronic operation.

[0039] In the example illustrated non-limitingly in Figures 1 and 2, the diagnostic device DD is part of the supervision computer CS. But this is not obligatory. Indeed, the diagnostic device DD could comprise its own dedicated computer, which is then coupled to the supervision computer CS, for example.

[0040] As illustrated non-limitingly in [Fig. 3], the (diagnostic) method, according to the invention, comprises a step 10-60 which is implemented each time the fuel cell PC needs to be supplied with dihydrogen by at least one tank RDn, and therefore when the valve of at least one tank RDn is opened on the order of the supervision computer CS. It is in fact essential that a tank valve RDn be open so that the associated pressure sensor can measure the pressure phmn of the stored dihydrogen.

[0041] Step 10-60 of the method comprises a sub-step 30 in which, when the valve of a tank RDn is open, the temperature then of the hydrogen it stores is estimated for the latter (RDn) (for example, the diagnostic device DD) using a first table and at least the pressure phmn of the hydrogen it stores (measured by the associated pressure sensor) and a current density dhecn of the hydrogen it stores. The first table establishes a correspondence between, on the one hand, pressure (of hydrogen) and density (of hydrogen) pairs and, on the other hand, temperatures (of hydrogen). It will be understood that the temperature corresponding to the pair consisting of the measured pressure phmn and the current density dhecn is determined in this first table, and that this determined temperature is the estimated temperature then.This first table can be determined in the laboratory or during a test or development phase of a vehicle similar to vehicle V.

[0042] Step 10-60 of the method also comprises a sub-step 60 in which, if the absolute value of the difference between the temperature thmn measured by the temperature sensor of the tank RDn and the estimated temperature then for this tank RDn is greater than a chosen threshold if, for example, the diagnostic device DD prohibits the use of this tank RDn. It is considered that the temperature sensor of the tank RDn is faulty and therefore that the latter (RDn) must no longer be used for safety reasons.

[0043] It will be noted that if the absolute value of the difference between the measured temperature thmn and the estimated temperature then for a reservoir RDn is less than or equal to the chosen threshold si (i.e. Ithmn - thenl < si), one (for example the diagnostic device DD) authorizes the use of this reservoir RDn, for example in a sub-step 50 of step 10-60, as illustrated non-limitingly in [Fig.3].

[0044] Thanks to this new type of diagnosis using at least a first correspondence table, it is now possible to determine with certainty each faulty temperature sensor and therefore each tank RDn which should no longer be used, whatever the number N (with N > 2) of tanks RDn of the vehicle V and independently of the temperatures thmn' measured in the other tanks RDn' (with n' n). As a result, there is no longer any risk of uncertainty in the decision imposing the prohibition of use of all the N tanks RDn and therefore preventing the use of the fuel cell PC, unless the diagnosis has determined that all the N temperature sensors were faulty.

[0045] For example, and as illustrated non-limitingly in [Fig. 3], step 10-60 may comprise a sub-step 40 in which one (for example the diagnostic device DD) can compare the estimated temperature then for the tank RDn with the chosen threshold si. If the absolute value of the difference between the measured temperature thmn and the estimated temperature then for the tank RDn is less than or equal to the chosen threshold si (i.e. Ithmn - thenl < si), one (for example the diagnostic device DD) performs sub-step 50 to authorize the use of this tank RDn. On the other hand, if the absolute value of the difference between the measured temperature thmn and the estimated temperature then for the tank RDn is greater than the chosen threshold si (i.e. Ithmn - thenl > si), one (for example the diagnostic device DD) performs sub-step 60 to prohibit the use of this tank RDn.

[0046] Also for example, in sub-step 40 of step 10-60 the threshold si can be between 3°C and 10°C. For example, this chosen threshold si can be equal to 5°C. But other values of the chosen threshold si can be used. For example, the value of the chosen threshold si can be determined during a test or development phase of a vehicle similar to the vehicle V.

[0047] Also for example, in sub-step 30 of step 10-60, for each tank RDn having its valve open, one (for example the diagnostic device DD) can start by determining in the first table a first temperature thldn which corresponds to the corresponding measured pressure phmn and current density dhecn. Then, one (for example the diagnostic device DD) can estimate a density error edhn as a function of the difference between the current density dhecn and a density dhcn calculated by means of a formula giving the density as a function of at least the first determined temperature thldn and the measured pressure phmn (i.e. edhn = dhecn - dhcn). Then, one (for example the diagnostic device DD) can estimate a temperature correction cthn as a function of at least this estimated density error edhn. Then, one (for example the diagnostic device DD) can estimate the temperature then as a function of this first determined temperature thldn and this estimated temperature correction cthn. In the presence of this option, the estimated temperature then is therefore (in the end) the first determined temperature thldn with a correction (cthn), preferably added (i.e. then = thldn + cthn).

[0048] For example, the formula mentioned above can be:

[0049] dhcn = phmn / (r* (thldn + 273.15)*z),

[0050] where z = ((c* thldn2) + (b* thldn) + a)*phmn + 1, a, b and c are constants, r = R / M, R = 8.3145 J*mol **K ', and M = 2.016 g / mol (molar mass of dihydrogen).

[0051] Also for example, in sub-step 30 of step 10-60, for each tank RDn having its valve open, one (for example the diagnostic device DD) can estimate the temperature correction cthn using a second table and the estimated density error edhn. This second table establishes a correspondence between density errors and temperature corrections. It will be understood that one determines in this second table the temperature correction which corresponds to the estimated density error edhn, and that this determined temperature correction is the temperature correction cthn. This second table can be determined in the laboratory or during a test or development phase of a vehicle similar to the vehicle V.

[0052] Also for example, and as illustrated non-limitingly in [Fig. 3], step 10-60 may comprise a sub-step 20 in which, for each tank RDn having its valve open, one (for example the diagnostic device DD) may estimate the current density dhecn as a function of an estimated current mass of dihydrogen rnhecn. Preferably, this estimation of the current density dhecn is only authorized on condition that the valve of the tank RDn has been open for at least a first chosen duration dcl to be in stabilized mode.

[0053] For example, this first chosen duration dcl can be between 3 seconds and 7 seconds. For example, this first chosen duration dcl can be equal to 5 seconds. But other values of first chosen duration dcl can be used. For example, the value of the first chosen duration dcl can be determined during a test or development phase of a vehicle similar to vehicle V.

[0054] It should be noted that it is also preferable, to ensure good initialization of the estimation of the temperature then in sub-step 30, that the latter (then) can only be used on condition that one (for example the diagnostic device DD) has started to determine the first temperature thldn for at least a second chosen duration dc2.

[0055] For example, this second chosen duration dc2 can be between 1 second and 3 seconds. For example, this second chosen duration dc2 can be equal to 2 seconds. But other values of second chosen duration dc2 can be used. For example, the value of second chosen duration dc2 can be determined during a test or development phase of a vehicle similar to vehicle V.

[0056] Also for example, in sub-step 20, for each tank RDn having its valve open, one (for example the diagnostic device DD) can estimate the current mass of dihydrogen mhecn as a function of the difference between an initial mass of dihydrogen rnhin at the opening of this valve and a mass of dihydrogen rnhcn consumed since this opening of the valve (i.e. mhecn = rnhin - rnhcn). It will be understood that, knowing the pressure phn at the opening of the valve of the tank RDn and the duration of opening of this valve of the tank RDn, one can deduce therefrom the mass of dihydrogen rnhcn consumed since this opening.

[0057] Also for example, and as illustrated non-limitingly in [Fig. 3], step 10-60 may comprise a sub-step 10 in which, for each tank RDn having its valve open, one (for example the diagnostic device DD) may estimate the initial mass of dihydrogen rnhin as a function of the density dhcn calculated by means of the formula mentioned above and giving the density as a function of at least the measured pressure phmn and a temperature which is this time the average value of temperatures measured in at least some of the tanks RDn. It will be understood that one cannot use the measured temperature thmn of the tank RDn, and therefore instead one can use, for example, the average value of the temperatures measured in the other tanks RDn' (with n' n), and if possible those having non-faulty temperature sensors.

[0058] It will also be noted that in sub-step 60 of step 10-60 it is possible to generate an alert (for example the diagnostic device DD can trigger the generation of an alert) for a user of the vehicle V (for example the driver) signaling a malfunction at the level of at least one tank RDn requiring its non-use and requiring an inspection in an after-sales service.

[0059] The user may be alerted, for example, by means of an illuminated indicator light (for example in the dashboard of the vehicle V) and / or a message displayed on at least one screen of the vehicle V (for example on the dashboard or a central instrument panel) or on the screen of a smartphone of the user, and / or broadcast by at least one loudspeaker of the vehicle V or of this smartphone. The aforementioned indicator light may, for example, be a service indicator light, but it could also be a indicator light dedicated to RDn tanks.

[0060] It will also be noted that in sub-step 60 of step 10-60, as a variant or in addition, at least one (for example the diagnostic device DD can trigger the recording of at least one) fault code representative of a malfunction at the level of at least one tank RDn can be recorded. For example, each fault code can be stored in a memory (possibly read-only) of the supervision computer CS.

[0061] It will also be noted, as illustrated non-limitingly in [Fig. 2], that the supervision computer CS (or the computer of the diagnostic device DD) can also comprise a mass memory MM1, in particular for storing each measured temperature thmn and each measured pressure phmn, as well as any intermediate data involved in all its calculations and processing operations. Furthermore, this supervision computer CS (or the computer of the diagnostic device DD) can also comprise an input interface IE for receiving at least each measured temperature thmn and each measured pressure phmn to use them in calculations or processing operations, possibly after having formatted and / or demodulated and / or amplified it, in a manner known per se, by means of a digital signal processor PR2.In addition, this supervision calculator CS (or the calculator of the diagnostic device DD) can also include an output interface IS, in particular to deliver a message (or order) containing a prohibition on the use of a tank RDn, and a possible message (or order) for triggering an alert and / or recording fault code(s).

[0062] It will also be noted that the invention also proposes a computer program product (or computer program) comprising a set of instructions which, when executed by processing means of the electronic circuit (or hardware) type, such as for example the processor PR1, is capable of implementing the diagnostic method described above to diagnose in the vehicle V each tank RDn which must be prohibited from use due to the failure of the associated temperature sensor.

Claims

Claims

1. Diagnostic method for a vehicle (V) comprising N tanks (RD) storing dihydrogen, each provided with a valve, in each of which the pressure and temperature of said stored dihydrogen are measured, and with N > 2, characterized in that it comprises a step (10-60) in which, when said valve of a tank (RDn) is open, a temperature of said stored dihydrogen is estimated for the latter (RDn) using a first table, establishing a correspondence between pressure and density pairs and temperatures, and at least said measured pressure and a current density of said stored dihydrogen, and, if the absolute value of a difference between said measured and estimated temperatures of said tank (RDn) is greater than a chosen threshold, the use of the latter (RDn) is prohibited.

2. Method according to claim 1, characterized in that in said step (10-60), for each tank (RDn) having its valve open, a first temperature corresponding to said measured pressure and corresponding current density is determined in said first table, then a density error is estimated as a function of a difference between said current density and a density calculated by means of a formula giving the density as a function of at least said first determined temperature and said measured pressure, then a temperature correction is estimated as a function of at least said estimated density error, then said temperature is estimated as a function of said first determined temperature and estimated temperature correction.

3. Method according to claim 2, characterized in that in said step (10-60), for each tank (RDn) having its valve open, said temperature correction is estimated using a second table, establishing a correspondence between density errors and temperature corrections, and said estimated density error.

4. Method according to one of claims 1 to 3, characterized in that in said step (10-60), for each tank (RDn) having its valve open, said current density is estimated as a function of an estimated current mass of dihydrogen.

5. Method according to claim 4, characterized in that in said step (10-60), for each tank (RDn) having its valve open, said current mass of dihydrogen is estimated as a function of a difference between an initial mass of dihydrogen at the opening of this valve and a mass of dihydrogen consumed since this opening of said valve.

6. Method according to claim 5, characterized in that in said step (10-60), for each tank (RDn) having its valve open, said initial mass of dihydrogen is estimated as a function of a density calculated by means of a formula giving the density as a function of at least said measured pressure and an average value of temperatures measured in at least some of said tanks (RDn).

7. Method according to one of claims 1 to 6, characterized in that in said step (10-60) said threshold is between 3°C and 10°C.

8. Computer program product comprising a set of instructions which, when executed by processing means, is capable of implementing the diagnostic method according to one of claims 1 to 7, in a vehicle (V) comprising N tanks (RD) storing dihydrogen, each equipped with a valve, in each of which the pressure and temperature of said stored dihydrogen are measured, and with N > 2, to diagnose each tank (RDn) to be prohibited from use.

9. Diagnostic device (DD) for a vehicle (V) comprising N tanks (RD) storing dihydrogen, each provided with a valve, in each of which the pressure and temperature of said stored dihydrogen are measured, and with N > 2, characterized in that it comprises at least one processor (PR1) and at least one memory (MD) arranged to carry out the operations consisting, when said valve of a tank (RDn) is open, in estimating for the latter (RDn) a temperature of said stored dihydrogen using a first table, establishing a correspondence between pressure and density pairs and temperatures, and at least said measured pressure and a current density of said stored dihydrogen, and, if the absolute value of a difference between said measured and estimated temperatures of said tank (RDn) is greater than a chosen threshold, in prohibiting the use of the latter (RDn).

10. Vehicle (V) comprising N tanks (RD) storing dihydrogen, each provided with a valve, in each of which the pressure and temperature of said stored dihydrogen are measured, and with N > 2, characterized in that it further comprises a diagnostic device (DD) according to claim 9.

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