DIAGNOSIS OF THE POSSIBILITY OF USING DIHYDROGEN TANKS FROM A VEHICLE

Abstract

A diagnostic procedure is implemented in a vehicle comprising N hydrogen storage tanks, each equipped with a valve, in which the pressure and temperature of the stored hydrogen are measured, with N ≥ 2. This procedure includes a step (10⁻⁶⁰) in which, when the valve of a tank is opened, the temperature of the stored hydrogen is estimated for that tank using a table that establishes a correspondence between pressure and density pairs and temperatures, and at least the measured pressure and current density of the stored hydrogen. If the absolute value of a difference between the measured and estimated temperatures of the tank exceeds a chosen threshold, the use of that tank is prohibited. Figure 3

Description

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

[0001] The invention relates to vehicles comprising at least two hydrogen tanks intended to power a fuel cell, and more specifically to the diagnosis within such vehicles of the possibility of using these tanks. Prior art

[0002] Some vehicles, possibly of the automobile type, include at least two hydrogen (or H2) tanks intended to supply a fuel cell responsible for supplying electrical energy to at least one electric drive machine of their powertrain (or PWM).

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

[0004] Currently, the diagnosis of failure of the 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 identified, and the use of the corresponding tank is immediately prohibited.

[0005] This type of diagnostic proves well-suited to cases where the number of tanks is relatively large. However, the fewer the tanks, the more difficult it is to determine which one(s) should no longer be used. This is particularly true when there are only two tanks. It is understandable that, in case of doubt, a situation could arise where no tank can be used, thus preventing the fuel cell from operating and potentially preventing the vehicle from moving if its powertrain does not also include a thermal engine or if it does not have a rechargeable battery to power its electric motor.

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

[0007] In particular, it proposes 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 of stored dihydrogen, and with N > 2.

[0008] This diagnostic method is characterized by the fact that it includes a step in which, when the valve of a tank is opened, a temperature of the stored dihydrogen is estimated for the latter using a first table, establishing a correspondence between pairs of pressure and density and temperatures, and at least the measured pressure and a current density of the stored dihydrogen, 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 a ban on the use of all N tanks, unless all N temperature sensors are simultaneously faulty.

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

[0011] - in its step, for each tank having its valve open, it is possible to determine in the first table a first temperature corresponding to the measured pressure and corresponding current density, then we can estimate a density error 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 we can estimate a temperature correction as a function of at least this estimated density error, then we can estimate the temperature as a function of the first determined temperature and estimated temperature correction;

[0012] - in the presence of the first option, in its stage, for each tank having its With the 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 with its valve open, one can estimate the current density as a function of an estimated current mass of dihydrogen;

[0014] - in the presence of the last option, in its step, for each tank having its With the valve open, we can estimate the mass of dihydrogen in progress based on the difference between an initial mass of dihydrogen at the opening of this valve and a mass of dihydrogen 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, the initial mass of dihydrogen can be estimated as a function of a density calculated using a formula that gives 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 stage, the threshold can be between 3°C and 10°C.

[0017] The invention also proposes a computer program product comprising a set of instructions which, when executed by processing means, is suitable for implementing a diagnostic process 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 which must be prohibited from use.

[0018] The invention also proposes a diagnostic device for equipping 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 includes at least one processor and at least one memory arranged to perform the operations consisting, when the valve of a tank is opened, of estimating for the latter a temperature of the stored dihydrogen using a first table, establishing a correspondence between pairs of pressure and density and temperatures, and at least the measured pressure and a current density of the stored dihydrogen, and, if the absolute value of a difference between the measured and estimated temperatures of the tank is greater than a chosen threshold, of prohibiting the use of the latter.

[0020] The invention also proposes a vehicle, possibly of the automobile type, 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 of that presented above. Brief description of the figures

[0021] Other features and advantages of the invention will become apparent from an examination of the detailed description below, and the accompanying drawings, in which:

[0022] [Fig. 1] schematically and functionally illustrates an example of an embodiment of a vehicle comprising a powertrain with an electric drive unit associated with a rechargeable power battery and a fuel cell coupled to two hydrogen tanks and associated with a supervisory computer, and a diagnostic device according to the invention,

[0023] [Fig.2] schematically and functionally illustrates an example of an embodiment of a supervisory computer comprising an example of an embodiment of a device 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 allow the diagnosis, among N RDn tanks storing dihydrogen (with n = 1 to N and N > 2) and equipping a vehicle V, of each RDn tank which must be prohibited from use due to the failure of the associated temperature sensor.

[0026] In what follows, vehicle V is considered, by way of non-limiting example, to be of the automobile type. For example, it is a car, as illustrated in [Fig. 1]. However, the invention is not limited to this type of vehicle. It relates to any type of vehicle (land, sea (or river), or air) comprising at least two hydrogen tanks intended to supply a fuel cell responsible for providing electrical energy to at least one electric drive unit of the powertrain.

[0027] Furthermore, in what follows, by way of non-limiting example, vehicle V is considered to comprise a powertrain (or PWM) of the all-electric type (and therefore whose propulsion is provided exclusively by at least one electric motor). However, the PWM could be of the hybrid type (thermal and electric).

[0028] Figure 1 schematically illustrates an example of an embodiment of a vehicle V comprising a diagnostic device DD according to the invention and an electric powertrain (and therefore an electric drive machine 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 in Figure 1, which is not exhaustive, the vehicle V comprises only two tanks RDn (i.e., n = 1 or 2). However, 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 powertrain which, in this case, is purely electric and therefore includes, in particular, an electric drive machine, a drive shaft, and a transmission shaft. The term "electric drive machine" here refers to an electric machine arranged to provide motor torque to move the vehicle V when supplied with electrical energy, and possibly to recover torque in the transmission chain.

[0030] The electric drive machine MME (here an electric motor) is supplied with electrical energy by the rechargeable power battery BP, and by a battery Fuel PC coupled to N tanks RDn (here N = 2), storing dihydrogen. Furthermore, this electric motive machine MME is coupled to the motor shaft, to supply it with motor 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 axle Tl is located here in the front PVV section of the vehicle V. Therefore, in this example, the RV wheels of the first axle Tl are both driving and steering wheels. However, in a variant, this first axle Tl could be the one referred to here as T2, located in the rear PRV section of the vehicle V, and in this case, the (front) RV wheels are only steering wheels (the rear wheels of the second rear axle T2 then being at least driving wheels and also possibly steering wheels).

[0032] The BP power battery and the PC fuel cell are also responsible for supplying an on-board network (not illustrated) 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 include electrical energy storage cells, possibly electrochemical (for example, 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 by way of illustration). But it could also 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 to the reduction on another electrode of an oxidant, such as oxygen from the air.

[0035] Although not shown in [Fig. 1], access to each RDn tank is controlled by a valve whose open or closed state is controlled by a CS supervisory computer as needed. Furthermore, each RDn tank is associated with a temperature sensor, responsible for measuring the temperature thmn of the dihydrogen it stores, and a pressure sensor, responsible for measuring the pressure phmn of the dihydrogen it stores.

[0036] As mentioned above, the invention proposes in particular a diagnostic method intended to allow diagnosis, among the N RDn tanks, of 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 for this purpose includes 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 implemented as a combination of electrical or electronic circuits or components (or “hardware”) and software modules (or “software”). For example, it could be a microcontroller.

[0038] The MD memory is random access memory (RAM) to store instructions for the implementation by the PR1 processor of at least part of the diagnostic process. The PR1 processor may comprise integrated (or printed) circuits, or several integrated (or printed) circuits connected by wired or wireless connections. An integrated (or printed) circuit is defined as any type of device capable of performing at least one electrical or electronic operation.

[0039] In the example illustrated, but not limited to, Figures 1 and 2, the DD diagnostic device is part of the CS supervisory control unit. However, this is not mandatory. Indeed, the DD diagnostic device could comprise its own dedicated control unit, which is then coupled to the CS supervisory control unit, for example.

[0040] As illustrated, without limitation, in [Fig. 3], the (diagnostic) method according to the invention comprises a step 10-60 which is implemented each time the PC fuel cell needs to be supplied with dihydrogen from at least one RDn tank, and therefore when the valve of at least one RDn tank is opened on command from the CS supervisory computer. It is indeed essential that an RDn tank valve be open so that the associated pressure sensor can measure the phmn pressure of the stored dihydrogen.

[0041] Step 10-60 of the process includes a substep 30 in which, when the valve of a tank RDn is opened, the temperature then of the dihydrogen stored in the tank (RDn) is estimated (for example, by the diagnostic device DD) using a first table and at least the pressure phmn of the dihydrogen it stores (measured by the associated pressure sensor) and a current density dhecn of the dihydrogen it stores. The first table establishes a correspondence between, on the one hand, pairs of pressure (of dihydrogen) and density (of dihydrogen) and, on the other hand, temperatures (of dihydrogen). 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 testing or development phase of a vehicle similar to the V vehicle.

[0042] Step 10-60 of the process also includes a substep 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 exceeding a chosen threshold, the use of this RDn tank is prohibited (for example, by the DD diagnostic device). This is because the RDn tank's temperature sensor is considered faulty, and therefore the tank (RDn) should 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 tank RDn is less than or equal to the threshold chosen si (i.e. Ithmn - thenl < si), on (for example the diagnostic device DD) allows the use of this tank RDn, for example in a sub-step 50 of step 10-60, as illustrated non-limitingly on [Fig.3].

[0044] Thanks to this new type of diagnostic using at least one initial lookup table, it is now possible to definitively identify each faulty temperature sensor and therefore each RDn tank that should no longer be used, regardless of the number N (with N > 2) of RDn tanks in vehicle V and independently of the thmn' temperatures measured in the other RDn' tanks (with n' ≤ n). Consequently, there is no longer a risk of decision uncertainty that would prohibit the use of all N RDn tanks and thus prevent the use of the PC fuel cell, unless the diagnostic has determined that all N temperature sensors are faulty.

[0045] For example, and as illustrated non-limitingly in [Fig. 3], step 10-60 may include a substep 40 in which the estimated temperature (then) for tank RDn can be compared to the chosen threshold (si). If the absolute value of the difference between the measured temperature (thmn) and the estimated temperature (then) for tank RDn is less than or equal to the chosen threshold (si) (i.e., Ithmn - thenl < si), substep 50 is performed (i.e., the diagnostic device DD) to allow the use of tank RDn. Conversely, if the absolute value of the difference between the measured temperature (thmn) and the estimated temperature (then) for tank RDn is greater than the chosen threshold (si) (i.e., Ithmn - thenl > si), substep 60 is performed (i.e., the diagnostic device DD) to prohibit the use of tank RDn.

[0046] Also, for example, in substep 40 of step 10-60, the threshold si can be between 3°C and 10°C. As an 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 testing or development phase of a vehicle similar to vehicle V.

[0047] Also for example, in substep 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 density during dhecn. Then, we (for example, the DD diagnostic device) can estimate a density error edhn based on the difference between the current density dhecn and a density dhcn calculated using a formula that gives the density as a function of at least the first determined temperature thldn and the measured pressure phmn (i.e., edhn = dhecn - dhcn). Then, we (for example, the DD diagnostic device) can estimate a temperature correction cthn based on at least this estimated density error edhn. Then, we (for example, the DD diagnostic device) can estimate the temperature then based on this first determined temperature thldn and this estimated temperature correction cthn. With this option, the estimated temperature then is therefore (ultimately) 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 substep 30 of step 10-60, for each tank RDn with its valve open, the temperature correction cthn can be estimated (for example, by the diagnostic device DD) 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 the temperature correction corresponding to the estimated density error edhn is determined in this second table, and that this determined temperature correction is the temperature correction cthn. This second table can be determined in the laboratory or during a testing or development phase of a vehicle similar to vehicle V.

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

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

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

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

[0056] Also, for example, in substep 20, for each tank RDn with its valve open, one (for example, the diagnostic device DD) can estimate the mass of dihydrogen being consumed 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 tank RDn and the duration of the opening of this valve of tank RDn, one can deduce 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 include a substep 10 in which, for each tank RDn with its valve open, the initial mass of dihydrogen rnhin can be estimated (for example, by the diagnostic device DD) as a function of the density dhcn calculated using the formula mentioned above, which gives the density as a function of at least the measured pressure phmn and a temperature that is this time the average value of temperatures measured in at least some of the tanks RDn. It will be understood that the measured temperature thmn of tank RDn cannot be used, and therefore, instead, the average value of the temperatures measured in the other tanks RDn' (with n' ≤ n) can be used, and if possible, those with non-faulty temperature sensors.

[0058] It will also be noted that in substep 60 of step 10-60 an alert can be generated (for example the diagnostic device DD can trigger the generation of an) for a user of the vehicle V (for example the driver) indicating a malfunction in at least one tank RDn requiring its non-use and requiring 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 instrument panel of vehicle V) and / or a message displayed on at least one screen of vehicle V (for example, the instrument panel or a central instrument cluster) or on the screen of the user's smartphone, and / or broadcast by at least one speaker of vehicle V or of that smartphone. The aforementioned indicator could, for example, be a service indicator, but it could also be an indicator dedicated to RDn tanks.

[0060] It should also be noted that in substep 60 of step 10-60, alternatively or additionally, at least one fault code representing a malfunction in at least one RDn tank can be recorded (for example, the DD diagnostic device can trigger the recording of at least one). For example, each fault code can be stored in a (possibly read-only) memory of the CS supervisory control unit.

[0061] It should also be noted, as illustrated but not limited to [Fig. 2], that the CS monitoring computer (or the DD diagnostic device computer) may also include 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. Furthermore, this CS monitoring computer (or the DD diagnostic device computer) may also include an IE input interface for receiving at least each measured temperature thmn and each measured pressure phmn for use in calculations or processing, possibly after having been shaped and / or demodulated and / or amplified, in a manner known per se, by means of a PR2 digital signal processor.Furthermore, this CS supervisory computer (or the DD diagnostic device computer) may also include an IS output interface, notably to deliver a message (or command) containing a prohibition on the use of an RDn tank, and a possible message (or command) to trigger an alert and / or record 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 type of electronic circuits (or hardware), such as for example the PR1 processor, is suitable for implementing the diagnostic process 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

Demands

1. Diagnostic method for a vehicle (V) comprising N tanks (RD) storing dihydrogen, each equipped with a valve, in each of which 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 opened, a temperature of said stored dihydrogen is estimated for the latter (RDn) using a first table, establishing a correspondence between pairs of pressure and density 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. A method according to any 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 dihydrogen mass.

5. The method according to claim 4, characterized in that in said step (10-60), for each tank (RDn) with its valve open, said mass of dihydrogen in use is estimated as a function of the difference between an initial mass of dihydrogen at the opening of this valve and a A large amount of dihydrogen consumed since the opening of the 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. A method according to any one of claims 1 to 6, characterized in that in said step (10-60) said threshold is between 3°C and 10°C.

8. Product computer program comprising a set of instructions which, when executed by processing means, is suitable for implementing the diagnostic method according to any 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 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 equipped with a valve, in each of which 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 perform the operations consisting, when said valve of a tank (RDn) is opened, of estimating for the latter (RDn) a temperature of said stored dihydrogen using a first table, establishing a correspondence between pairs of pressure and density 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, of prohibiting the use of the latter (RDn).

10. Vehicle (V) comprising N tanks (RD) storing dihydrogen, each equipped with a valve, in each of which 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.

Images