Flowmeter failure determination method and hydrogen filling device

Abstract

This flowmeter failure determination method comprises: a step for weighing the amount of hydrogen gas filling the fuel tank of an automobile by using a flowmeter (S114); a step for acquiring information about the pressure and temperature of the fuel tank (S102); a step for computing the amount of hydrogen gas filling the fuel tank on the basis of the acquired pressure and temperature and the volume of the fuel tank, with the expansion rate of the fuel tank accounted for (S104, S112); and a step for determining, using an error value between the weighed filling amount and the computed filling amount, whether the flowmeter has failed (S118).

Description

[Technical Field]

[0001] The present invention relates to a technique for determining a malfunction of a measuring device provided in a hydrogen filling device. [Background technology]

[0002] A method for diagnosing flow meter failures in a measuring machine has been devised which includes a step of determining whether or not there is a flow meter failure using multiple error values ​​based on multiple past actual data stored in a memory device and the error value at the end of the current hydrogen gas filling, between the measured filling amount measured using a flow meter at the end of filling and the calculated filling amount at the end of filling calculated using the tank's pressure, temperature, and capacity (see Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2019-207196 Summary of the Invention [Problem to be solved by the invention]

[0004] However, the difference between the measured filling amount and the calculated filling amount is usually not zero due to fuel tank expansion, and an offset exists. Therefore, in the fault diagnosis method described above, when determining a fault using the difference between the measured filling amount and the calculated filling amount as an error value, a tolerance is set that takes a predetermined offset into account. However, further research by the inventors of the present application has revealed that the expansion rate of the fuel tank is not necessarily constant and depends on the filling pressure.

[0005] The present invention has been made in view of the above circumstances, and one of its exemplary purposes is to provide a new technique for improving the accuracy of determining a fault in a flow meter. [Means for solving the problem]

[0006] A method for determining a flow meter malfunction in one embodiment of the present invention includes the steps of measuring the amount of hydrogen gas to be filled into a fuel tank of an automobile using a flow meter, acquiring information on the pressure and temperature of the fuel tank, calculating the amount of hydrogen gas to be filled into the fuel tank based on the acquired pressure and temperature and the capacity of the fuel tank taking into account the expansion rate of the fuel tank, and determining whether or not the flow meter malfunctions using an error value between the measured filling amount and the calculated filling amount. [Effects of the Invention]

[0007] According to an aspect of the present invention, the accuracy of determining a failure in a flow meter can be improved. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a diagram showing an example of the configuration of a hydrogen filling system of a hydrogen station according to an embodiment of the present invention; [Figure 2] 2 is a block diagram showing an example of the internal configuration of a control circuit that controls the entire hydrogen filling system according to the present embodiment. FIG. [Figure 3] FIG. 10 is a diagram showing an example of the change in percent error of a flow meter with respect to the number of fills. [Figure 4] FIG. 10 is a diagram showing another example of the change in percent error of a flow meter with respect to the number of fills. [Figure 5] 3 is a flowchart showing some of the steps of a hydrogen gas filling method according to the present embodiment. [Figure 6] 10 is a flowchart showing the remaining steps of the hydrogen gas filling method according to the present embodiment. [Figure 7] FIG. 1 is a diagram for explaining a method of filling hydrogen gas using a multistage pressure accumulator. [Figure 8] 1 is a graph showing the relationship between the differential pressure during filling and the filling amount error for each filling data in Table 1. DETAILED DESCRIPTION OF THE INVENTION

[0009] First, aspects of the present invention will be listed. A flow meter failure determination method according to one aspect of the present invention includes the steps of measuring the amount of hydrogen gas to be filled into a fuel tank of an automobile using a flow meter, acquiring information on the pressure and temperature of the fuel tank, calculating the amount of hydrogen gas to be filled into the fuel tank based on the acquired pressure and temperature and the capacity of the fuel tank taking into account the expansion rate of the fuel tank, and determining whether or not the flow meter has a failure using an error value between the measured amount and the calculated amount.

[0010] According to this aspect, the fuel tank expansion rate is taken into account when calculating the fill volume, which improves the calculation accuracy of the fill volume. In other words, the error value between the measured fill volume and the calculated fill volume is reduced, and the variance is also reduced, which improves the accuracy of determining a flow meter failure.

[0011] The method may further include the step of outputting the determination result. By outputting the determination result as to whether or not the flow meter has a malfunction, it is possible to quickly grasp whether or not the flow meter has a malfunction.

[0012] The method may further include the steps of: calculating a first weight of hydrogen gas in the fuel tank before the start of filling based on a first pressure, a first temperature, and a first volume of the fuel tank before the start of filling; and calculating a second weight of hydrogen gas in the fuel tank after the start of filling based on a second pressure, a second temperature, and a second volume of the fuel tank after the start of filling. The calculated filling amount may be calculated using the first weight and the second weight. By using the first volume before the start of filling and the second volume after the start of filling, the calculation accuracy of the filling amount can be improved.

[0013] The first volume may be calculated using the expansion rate and the first pressure, and the second volume may be calculated using the expansion rate and the second pressure. Calculating the first volume using the first pressure allows for accurate calculation of the first weight before the start of filling. Particularly, under conditions where the pressure inside the fuel tank is relatively low before the start of filling, the first volume taking the expansion rate into consideration can be calculated with high accuracy. Calculating the second volume using the second pressure allows for accurate calculation of the second weight after the start of filling. Particularly, under conditions where the pressure inside the fuel tank is relatively high after the start of filling, the second volume taking the expansion rate into consideration can be calculated with high accuracy. This improves the accuracy of calculating the filling amount compared to when the volume is constant regardless of the pressure inside the fuel tank.

[0014] The first volume may be calculated using a first function that is nonlinear with respect to the first pressure, and the second volume may be calculated using a second function that is linear or nonlinear with respect to the second pressure. The first and second functions are expressed, for example, by mathematical expressions stored in a storage device. The inventors of the present application have noticed that when the filling volume is large (when the difference between the first pressure and the second pressure is large), the discrepancy between the measured filling volume and the calculated filling volume becomes large. In particular, when the first pressure is low, the filling volume may be large. By calculating the first volume using a first function that is nonlinear with respect to the first pressure, the calculation accuracy of the first volume can be improved compared to when the first volume is calculated using a function proportional to the pressure in the fuel tank.

[0015] The method may further include a step of identifying the type of fuel tank. The first function and the second function may be set according to the type of fuel tank. This makes it possible to determine whether the flow meter has malfunctioned when filling hydrogen gas into fuel tanks of various vehicle types.

[0016] Another aspect of the present invention is a hydrogen filling device that includes a measuring device that uses a flow meter to measure the amount of hydrogen gas to be filled into a fuel tank of an automobile, an acquisition unit that acquires information on the pressure and temperature of the fuel tank, a fill amount calculation unit that calculates the amount of hydrogen gas to be filled into the fuel tank from the measuring device based on the acquired pressure and temperature and the fuel tank capacity taking into account the expansion rate of the fuel tank, and a determination unit that determines whether the flow meter is faulty using an error value between the fill amount measured using the flow meter and the calculated fill amount.

[0017] According to this aspect, the fuel tank expansion rate is taken into account when calculating the fill volume, which improves the calculation accuracy of the fill volume. In other words, the error value between the measured fill volume and the calculated fill volume is reduced, and the variance is also reduced, which improves the accuracy of determining a flow meter failure.

[0018] Any combination of the above components and any transformation of the present invention into a method, device, system, etc. are also valid aspects of the present invention. Appropriate combinations of the above elements may also be included in the scope of the invention for which patent protection is sought by this patent application.

[0019] The present invention will be described below with reference to the drawings based on preferred embodiments. The embodiments are illustrative and do not limit the invention, and all features and combinations thereof described in the embodiments are not necessarily essential to the invention. The same or equivalent components, parts, and processes shown in the drawings are designated by the same reference numerals, and redundant descriptions will be omitted where appropriate. The scale and shape of each part shown in the drawings are set for convenience to facilitate explanation and should not be interpreted as limiting unless otherwise specified. The same components may have slightly different scales between the drawings. Furthermore, when terms such as "first" and "second" are used in this specification or claims, unless otherwise specified, they do not represent any order or importance, but are used to distinguish one configuration from another.

[0020] First, an example of a hydrogen filling system to which the present invention can be applied will be described. Fig. 1 is a diagram showing an example of the configuration of a hydrogen filling system for a hydrogen station according to this embodiment. In Fig. 1, a hydrogen filling system 500 is arranged inside a hydrogen station 102. The hydrogen filling system (hydrogen filling device) 500 comprises a multi-stage pressure accumulator 101, a dispenser (metering device) 30, a compressor 40, and a control circuit 100. The multi-stage pressure accumulator 101 is made up of a plurality of pressure accumulators 10, 12, 14 with different lower limit operating pressures.

[0021] In the example of Figure 1, a multi-stage pressure accumulator 101 is configured from three pressure accumulators 10, 12, and 14. For example, pressure accumulator 10 acts as a first bank with a low minimum usable pressure, pressure accumulator 12 acts as a second bank with an intermediate minimum usable pressure, and pressure accumulator 14 acts as a third bank with a high minimum usable pressure. However, this is not limited to this. The pressure accumulators used as the first to third banks can be interchanged as needed. The hydrogen station 102 also includes a curdle, an intermediate pressure accumulator, or a hydrogen production device (none of which are shown). A hydrogen trailer (not shown) arrives at the hydrogen station 102 to deliver filled hydrogen gas.

[0022] In FIG. 1, the suction side of the compressor 40 is connected by piping to the above-mentioned curdle, intermediate pressure accumulator, filling tank of the hydrogen trailer, or hydrogen production device.

[0023] The discharge side of compressor 40 is connected to pressure accumulator 10 by piping via valve 21. Similarly, the discharge side of compressor 40 is connected to pressure accumulator 12 by piping via valve 23. Similarly, the discharge side of compressor 40 is connected to pressure accumulator 14 by piping via valve 25.

[0024] The pressure accumulator 10 is connected to the dispenser 30 by piping via a valve 22. The pressure accumulator 12 is connected to the dispenser 30 by piping via a valve 24. The pressure accumulator 14 is connected to the dispenser 30 by piping via a valve 26. In this way, the dispenser 30 is commonly connected to the pressure accumulators 10, 12, and 14 that constitute the multi-stage pressure accumulator 101.

[0025] 1 , a shutoff valve 36, a flow rate adjustment valve 33, a flow meter 37, a cooler 32 (precooler), a shutoff valve 38, an emergency release coupler 41, and a control circuit 43 are arranged inside the dispenser 30. A nozzle 44 extending to the outside of the dispenser 30 is arranged in the dispenser 30. The dispenser 30 sends hydrogen gas (hydrogen fuel) supplied from the multi-stage pressure accumulator 101 to the cooler 32 via the shutoff valve 36, the flow rate adjustment valve 33, and the flow meter 37. At this time, the flow rate per unit time of the hydrogen gas supplied from the multi-stage pressure accumulator 101 is controlled by the flow rate adjustment valve 33.

[0026] The dispenser 30 measures the amount of hydrogen gas to be filled from the multi-stage accumulator 101 into the fuel tank 202 of the FCV (fuel cell vehicle) 200. Specifically, the mass flow rate of the hydrogen gas to be filled into the fuel tank 202 is measured by a flow meter 37. In this embodiment, for example, a Coriolis mass flow meter is used as the flow meter 37. The control circuit 43 measures the filling amount by integrating the mass flow rate measured by the flow meter 37. The filling amount measured using the flow meter 37 is also referred to as the "measured filling amount." The hydrogen gas to be filled is cooled to, for example, -40°C by a cooler 32. The cooled hydrogen gas is filled into the fuel tank 202 via a shutoff valve 38, an emergency release coupler 41, and a nozzle 44 using a pressure difference.

[0027] The control circuit 43 is configured to be able to communicate with an on-board device 204 in the FCV 200. The control circuit 43 can wirelessly communicate with the on-board device 204 using, for example, infrared rays. The control circuit 43 is connected to a control circuit 100 that controls the entire hydrogen filling system 500. A display panel 39 is disposed on the outer surface of the dispenser 30. Warning lamps 34, 35 are disposed inside the display panel 39.

[0028] In the hydrogen filling system 500 in FIG. 1 , multiple pressure gauges are arranged at different locations in the flow path of the hydrogen fuel from the multi-stage pressure accumulator 101 to the outlet of the dispenser 30. Specifically, the pressure in the pressure accumulator 10 is measured by a pressure gauge 11. The pressure in the pressure accumulator 12 is measured by a pressure gauge 13. The pressure in the pressure accumulator 14 is measured by a pressure gauge 15. The pressure near the inlet in the dispenser 30 is measured by a pressure gauge 27. The pressure near the outlet in the dispenser 30 is measured by a pressure gauge 28.

[0029] In the example of FIG. 1, pressure gauge 27 measures the pressure upstream (primary side) of shutoff valve 36 located on the primary side of cooler 32. Pressure gauge 28 measures the pressure near emergency release coupler 41 on the secondary side of cooler 32. Pressure data measured by each pressure gauge is output to control circuit 100 constantly or at predetermined sampling intervals (for example, 10 ms to several seconds). In other words, control circuit 100 monitors the pressure measured by each pressure gauge constantly or at predetermined sampling intervals.

[0030] The pressure of fuel tank 202 is measured by a pressure gauge 206 mounted on FCV 200. As will be described later, the pressure of fuel tank 202 is monitored constantly or at predetermined sampling intervals (for example, every 10 ms to several seconds) while communication between on-board device 204 and control circuit 43 is established.

[0031] The temperature of the hydrogen gas near the outlet in the dispenser 30 is measured by a thermometer 29. The thermometer 29 is on the secondary side of the cooler 32 and measures the temperature, for example, near the emergency release coupler 41. The outside air temperature near the dispenser 30 is measured by a thermometer 31. The temperature data measured by each thermometer is output to the control circuit 100 constantly or at a predetermined sampling interval (for example, 10 milliseconds to several tens of seconds). In other words, the control circuit 100 monitors the temperatures measured by each thermometer constantly or at a predetermined sampling interval.

[0032] The temperature of fuel tank 202 is measured by a thermometer 207 mounted on FCV 200. As will be described later, the temperature of fuel tank 202 is monitored constantly or at predetermined sampling intervals (for example, every 10 ms to several seconds) while communication between in-vehicle device 204 and control circuit 43 is established.

[0033] Hydrogen gas stored in a curdle, intermediate pressure accumulator, or tank of a hydrogen trailer is decompressed to a low pressure (e.g., 0.6 MPa) by respective regulators (not shown) controlled by the control circuit 100, and then supplied to the suction side of the compressor 40. Similarly, hydrogen gas produced in a hydrogen production device is supplied to the suction side of the compressor 40 at a low pressure (e.g., 0.6 MPa). Under the control of the control circuit 100, the compressor 40 compresses the hydrogen gas supplied at low pressure and supplies the compressed hydrogen gas to each of the accumulators 10, 12, and 14 of the multi-stage accumulator 101. The compressor 40 compresses the hydrogen gas until the pressure inside each of the accumulators 10, 12, and 14 reaches a predetermined high pressure (e.g., 82 MPa). In other words, the compressor 40 controls the secondary side pressure P OUT The hydrogen gas is compressed to a predetermined high pressure (for example, 82 MPa).

[0034] The control circuit 100 determines which of the curdle, intermediate pressure accumulator, hydrogen trailer, and hydrogen production device will be the supply source for supplying hydrogen gas to the suction side of the compressor 40. Similarly, the control circuit 100 determines which of the pressure accumulators 10, 12, and 14 the hydrogen gas will be supplied to from the compressor 40 by controlling the opening and closing of valves 21, 23, and 25. The control circuit 100 may also perform control so that hydrogen gas is supplied from the compressor 40 to two or more pressure accumulators simultaneously.

[0035] In the above example, the pressure P INIn the above example, the hydrogen gas is depressurized to a predetermined low pressure (e.g., 0.6 MPa), but the present invention is not limited to this. For example, when hydrogen gas stored in a curdle, intermediate pressure accumulator, or hydrogen trailer is supplied to the suction side of the compressor 40, the hydrogen gas may not be depressurized, or may be depressurized to a pressure higher than the predetermined low pressure (e.g., 0.6 MPa).

[0036] The hydrogen gas stored in the multistage pressure accumulator 101 is cooled by the cooler 32 in the dispenser 30 and supplied from the dispenser 30 to the FCV 200 .

[0037] 2 is a block diagram showing an example of the internal configuration of a control circuit that controls the entire hydrogen filling system according to this embodiment. In FIG. 2, the control circuit 100 includes a communication control circuit 50, a memory 51, a receiver 52, a target pressure / temperature calculator 54, a system controller 58, a pressure recovery controller 61, a supply controller 63, a bank pressure receiver 66, a dispenser information receiver 67, an output unit 74, a gas weight calculator 85, a determination unit 86, a filling amount calculator 87, a filling amount error calculator 89, a determination unit 90, a determination unit 91, a recording / calculation unit 92, an average error calculator 93, an error difference value calculator 94, a determination unit 95, a setting unit 96, a monitor 76, and storage devices 80, 84, and 86, such as magnetic disk drives. The pressure recovery controller 61 includes a valve controller 60 and a compressor controller 62. The supply controller 63 includes a dispenser controller 64 and a valve controller 65.

[0038] Each of the units, such as the receiving unit 52, the target pressure / temperature calculation unit 54, the system control unit 58, the pressure recovery control unit 61 (the valve control unit 60 and the compressor control unit 62), the supply control unit 63 (the dispenser control unit 64 and the valve control unit 65), the bank pressure receiving unit 66, the dispenser information receiving unit 67, the output unit 74, the gas weight calculation unit 85, the determination unit 86, the filling amount calculation unit 87, the filling amount error calculation unit 89, the determination unit 90, the determination unit 91, the recording / calculation unit 92, the average error calculation unit 93, the error difference value calculation unit 94, the determination unit 95, and the setting unit 96, includes a processing circuit, which may include an electric circuit, a computer, a processor, a circuit board, or a semiconductor device. For example, a central processing unit (CPU), a field-programmable gate array (FPGA), or an application-specific integrated circuit (ASIC) may be used as the processing circuit.

[0039] The above-mentioned units may use a common processing circuit (the same processing circuit), or may use different processing circuits (separate processing circuits). Input data required by the above-mentioned units or the results of calculations performed by the above-mentioned units are stored in memory 51 each time.

[0040] The storage device 80 stores FCV information such as the pressure P, temperature T, and volume V of the fuel tank 202 received from the FCV 200. The storage device 80 also stores a conversion table 81 that indicates the correlation between the weight N of hydrogen gas in the fuel tank 202 corresponding to the FCV information and filling information such as the target pressure Pg and target temperature Tg of the hydrogen gas to be filled into the fuel tank 202. The storage device 80 also stores a correction table 82 for correcting the results obtained from the conversion table 81.

[0041] The bank pressure receiving unit 66 receives the pressures measured by the pressure gauges 11, 13, and 15 in the accumulator 10, either constantly or at predetermined sampling intervals, and stores the information together with the time of reception in the storage device 84. The dispenser information receiving unit 67 receives the pressures measured by the pressure gauges 27 and 28 in the dispenser 30, either constantly or at predetermined sampling intervals, and stores the information together with the time of reception in the storage device 84. The dispenser information receiving unit 67 receives the temperature measured by the thermometer 29 in the dispenser 30, either constantly or at predetermined sampling intervals, and stores the information together with the time of reception in the storage device 84.

[0042] As described above, the amount (mass flow rate) of hydrogen gas filled into the fuel tank 202 is measured using the flow meter 37. The flow meter 37 measures the mass flow rate at the instant of filling and generates a pulse for each minute flow rate unit, for example, 1 g. The pulse signal is output to the control circuit 43. The control circuit 43 counts the number of pulses generated from the start of filling and integrates the mass flow rate to measure the metered filling amount Mm.

[0043] During filling, the measured filling amount Mm is displayed on the display panel 39 arranged on the outer surface of the dispenser 30 as a value that changes every moment, and is also output to the control circuit 100. The measured filling amount Mm is the source data for the fee paid by the consumer. In other words, the fee paid by the consumer (user) is the amount obtained by multiplying the displayed measured filling amount Mm by the price of hydrogen gas per unit filling amount. Therefore, the measurement accuracy of the flow meter 37 is important.

[0044] As described above, the FCV 200 outputs FCV information such as the pressure P, temperature T, and volume V of the fuel tank 202. The display panel 39 may display these numerical values. Specifically, the numerical values ​​of the pressure Pt and temperature Tt of the fuel tank 202 at the current time t may be displayed on the display panel 39 while changing moment by moment.

[0045] The control circuit 100 calculates the density ρ(P,T) of the hydrogen gas in the fuel tank 202 using the pressure P and temperature T of the fuel tank 202, as well as the compressibility specific to hydrogen. The control circuit 100 calculates the weight N of the hydrogen gas in the fuel tank 202, N=ρ(P,T)×V, by multiplying the density ρ(P,T) by the volume V of the fuel tank 202. The control circuit 100 calculates, as the weight N, a first weight N1 before the start of filling and a second weight N2 after the start of filling. The first weight N1 is calculated by multiplying the density ρ(P1,T1), calculated from the first pressure (initial pressure) P1 and the first temperature (initial temperature) T1 of the fuel tank 202 before the start of filling, by the volume V (i.e., N1=ρ(P1,T1)×V). The second weight N2 is calculated by multiplying the density ρ(P2, T2) calculated from the second pressure P2 and second temperature T2 after the start of filling by the volume V (i.e., N2 = ρ(P2, T2) × V). Here, "after the start of filling" includes timing at any time t during filling and timing at the end of filling.

[0046] The control circuit 100 calculates the hydrogen gas filling amount Mc by subtracting the first weight N1 from the second weight N2 (i.e., Mc = N2 - N1). The filling amount calculated based on the first weight N1 and the second weight N2 is also referred to as the "calculated filling amount." The calculated filling amount Mc is a value calculated using the pressure P and temperature T of the fuel tank 202 and the compressibility specific to hydrogen, and is a value calculated by the PVT method (volumetric method). The calculated filling amount Mc corresponds to the weight of hydrogen gas filled into the fuel tank 202 since filling began.

[0047] The calculated fill volume Mc can be used to evaluate the validity of the measured fill volume Mm measured using the flow meter 37. Therefore, the percentage error of the flow meter 37 was evaluated by dividing the fill volume error ΔM, which is obtained by subtracting the calculated fill volume Mc from the measured fill volume Mm, by the calculated fill volume Mc and multiplying the result by 100.

[0048] FIG. 3 is a graph showing an example of the change in the percentage error of the flowmeter 37 with respect to the number of fills. The example in FIG. 3 shows an example in which no abnormalities occurred in the flowmeter 37 during the verification period. In FIG. 3, the vertical axis represents the percentage error of the flowmeter 37, and the horizontal axis represents the number of fills. As shown in FIG. 3, by verifying the magnitude of the percentage error over time based on the number of fills using many fill results, it is possible to continuously check the change in the flowmeter 37 over time. The results in FIG. 3 show that the percentage error of the flowmeter 37 is stable within a range Δ2. Furthermore, the reason why the percentage error of the flowmeter 37 is not zero and has an offset Δ1 on the positive side is because the fuel tank 202 expands during fill, causing a deviation in the calculation results using the PVT method due to the expansion.

[0049] FIG. 4 is a diagram showing another example of the change in the percentage error of the flow meter with respect to the number of fillings. The example in FIG. 4 shows an example in which an abnormality occurred in the flow meter 37 during a verification period. In FIG. 4, the vertical axis shows the percentage error of the flow meter 37, and the horizontal axis shows the number of fillings. In the example in FIG. 4, it can be seen that as the number of fillings increases, the variation in the percentage error of the flow meter 37 increases, and the value changes (shifts) significantly in stages twice, at fillings A and B. Regarding the way the value shifts, in the example in FIG. 4, the offset on the positive side shifts to the negative side. In this way, the large change in the percentage error of the flow meter 37 over a short period of time indicates that a major abnormality (failure) other than deterioration over time has occurred in the flow meter 37.

[0050] First, the variation in the percentage error of the flow meter 37 can only be determined by continuous verification over many filling cycles according to this embodiment. On the other hand, with the conventional gravimetric method, measurements are typically taken only about four times. Therefore, with the conventional gravimetric method, it is difficult to determine whether the variation has increased. Furthermore, with regard to a sudden large change (shift) in the percentage error of the flow meter 37, the point at which the large change (shift) in the percentage error of the flow meter 37 occurred can only be identified by continuous verification according to this embodiment, and an abnormality in the flow meter 37 can be detected.

[0051] The above results also show that it is useful to compare and verify the calculated filling amount Mc and the metered filling amount Mm. Therefore, in this embodiment, a fault diagnosis of the flow meter 37 is performed using the error value between the calculated filling amount Mc and the metered filling amount Mm. Note that, although the examples in Figures 3 and 4 have been described using percentage errors, the verifiable error value is not limited to this. Below, we will explain the case where the filling amount error ΔM = Mm - Mc, which is the difference between the calculated filling amount Mc and the metered filling amount Mm, is used as the error value.

[0052] Fig. 5 is a flowchart showing part of the steps of the hydrogen gas filling method according to this embodiment, and Fig. 6 is a flowchart showing the remaining steps of the hydrogen gas filling method according to this embodiment.

[0053] 5 and 6, the hydrogen gas filling method of this embodiment includes a determination step (S100), an FCV information receiving step (S102), a gas weight calculation step (S104), a determination step (S106), an initial weight setting step (S108), a filling step (S110), a filling amount calculation step (S112), a filling amount measurement step (S114), a filling amount error calculation step (S116), a determination step (S118), an alarm output step (S120), a determination step (S126), a filling stop processing step (S128), a recording and calculation step (S130), an average error calculation step (S132), a difference calculation step (S134), a determination step (S136), and an alarm output step (S138).

[0054] When the FCV 200 arrives at the hydrogen station 102, a worker at the hydrogen station 102 or a user of the FCV 200 connects (fits) and secures the nozzle 44 of the dispenser 30 to a receptacle in the fuel tank 202 of the FCV 200. The worker or user then presses a fill start button (not shown) in the display panel 39 of the dispenser 30.

[0055] In the determination step (S100), the control circuit 43 determines whether an operator or user has pressed the filling start button. If the filling start button has been pressed (S100 YES), the process proceeds to the FCV information receiving step (S102). If the start button has not been pressed (S100 NO), the process does not proceed to the next step. When the filling start button is pressed, communication is established between the vehicle-mounted device 204 and the control circuit 43 (repeater).

[0056] In the FCV information receiving step (S102), the receiver 52 receives FCV information such as the current (time t) temperature Tt, pressure Pt, and capacity V of the fuel tank 202 from the FCV 200. Specifically, the operation is as follows: When communication is established between the vehicle-mounted device 204 and the control circuit 43 (repeater), the vehicle-mounted device 204 outputs (transmits) the FCV information (tank information) in real time.

[0057] The FCV information is relayed through a control circuit 43 provided in the dispenser 30 and transmitted to a control circuit 100 that controls the entire hydrogen filling system 500. Within the control circuit 100, a receiver 52 receives the FCV information via the communication control circuit 50. The FCV information is monitored continuously or at predetermined sampling intervals (for example, 10 ms to several seconds) while communication is established between the vehicle-mounted device 204 and the control circuit 43. The received FCV information is stored in a storage device 80 together with information on the time of reception.

[0058] In the gas weight calculation step (S104), the gas weight calculation unit 85 uses the PVT method to calculate the weight Nt of hydrogen gas filled in the fuel tank 202 at the current time (time t). Specifically, the gas weight calculation unit 85 calculates the density ρ(Pt,Tt) of the hydrogen gas using the current pressure Pt and temperature Tt of the fuel tank 202 and the compressibility specific to hydrogen. The gas weight calculation unit 85 multiplies the density ρ(Pt,Tt) by the volume V of the fuel tank 202 to calculate the current weight Nt of the hydrogen gas in the fuel tank 202, Nt=ρ(Pt,Tt)×V.

[0059] In the determination step (S106), the determination unit 86 determines whether the determination process is the first determination process since the start of filling. If it is the first determination process (YES in S106), the process proceeds to the initial weight setting step (S108). If it is not the first determination process, that is, if it is the second or subsequent time since the start of filling (NO in S106), the process proceeds to the filling amount calculation step (S112) while continuing the filling step (S110) described below.

[0060] In the initial weight setting step (S108), if this is the first determination process in the determination step (S106), that is, before the start of filling, the setting unit 96 sets the calculated weight Nt of hydrogen gas as the first weight N1. The first weight N1 can be calculated as N1=ρ(P1, T1)×V using the FCV information (first temperature T1 and first pressure P1) before the start of filling.

[0061] In the filling step (S110), first, the target pressure / temperature calculation unit 54 reads the conversion table 81 from the storage device 80 and calculates the target pressure Pg and target temperature Tg corresponding to the first pressure P1, first temperature T1, and capacity V of the fuel tank 202, and the outside air temperature T'. The target pressure / temperature calculation unit 54 also reads the correction table 82 from the storage device 80 and corrects the numerical values ​​obtained from the conversion table 81. The correction table 82 is used to correct the numerical values ​​obtained from the conversion table 81 using correction values ​​set based on results obtained by experiments, simulations, or the like, when the results obtained from the data in the conversion table 81 alone have a large error. The calculated target pressure Pg and target temperature Tg are output to the system control unit 58.

[0062] Next, hydrogen gas starts to be filled from the multi-stage accumulator 101 into the fuel tank 202 via the dispenser 30 .

[0063] Figure 7 is a diagram illustrating a method of filling hydrogen gas using a multistage pressure accumulator. In Figure 7, the vertical axis represents pressure and the horizontal axis represents time. When differential pressure filling of hydrogen gas into FCV 200 is performed, typically, each of accumulators 10, 12, 14 of multistage pressure accumulator 101 is previously stored at the same pressure P0 (e.g., 82 MPa). Meanwhile, fuel tank 202 is at first pressure P1 at time t0, which is the start of filling. A case will be described where filling of fuel tank 202 with hydrogen gas is started from this state.

[0064] First, the filling of hydrogen gas from the first bank (for example, the pressure accumulator 10) into the fuel tank 202 begins. Specifically, the operation is as follows. Under the control of the system control unit 58, the supply control unit 63 controls the supply unit 106 to supply hydrogen gas from the pressure accumulator 10 to the fuel tank 202 of the FCV 200. Specifically, the system control unit 58 controls the dispenser control unit 64 and the valve control unit 65. The dispenser control unit 64 communicates with the control circuit 43 of the dispenser 30 via the communication control circuit 50 and controls the operation of the dispenser 30.

[0065] Specifically, first, the control circuit 43 adjusts the aperture of the flow rate adjustment valve in the dispenser 30 to open the shutoff valves 36 and 38 in the dispenser 30. Then, the valve control unit 65 outputs control signals to the valves 22, 24, and 26 via the communication control circuit 50 to control the opening and closing of each valve. Specifically, the valve 22 is opened and the valves 24 and 26 are kept closed. This causes hydrogen gas to be supplied from the accumulator 10 to the fuel tank 202. The hydrogen gas stored in the accumulator 10 due to the pressure difference between the accumulator 10 and the fuel tank 202 moves toward the fuel tank 202 at a filling rate adjusted by the flow rate adjustment valve, and the pressure in the fuel tank 202 gradually increases as indicated by the dotted line Pt. Accordingly, the pressure in the accumulator 10 (the graph indicated by "1st") gradually decreases. Then, at the point in time t1 when the pressure of the first bank falls below the lower limit of use, the accumulator to be used is switched from the accumulator 10 to the accumulator 12 of the second bank (for example).

[0066] When switching to the pressure accumulator 12, the valve control unit 65 outputs control signals to the valves 22, 24, and 26 via the communication control circuit 50 to control the opening and closing of each valve. Specifically, the valve 24 is opened, the valve 22 is closed, and the valve 26 is kept closed. This increases the pressure difference between the pressure accumulator 12 and the fuel tank 202, making it possible to maintain a high filling speed.

[0067] Then, the hydrogen gas stored in the pressure accumulator 12 due to the pressure difference between the second bank (e.g., pressure accumulator 12) and the fuel tank 202 moves toward the fuel tank 202, and the pressure in the fuel tank 202 gradually increases further as indicated by the dotted line Pt. Accordingly, the pressure in the pressure accumulator 12 (the graph indicated by "2nd") gradually decreases. Then, at the point in time t2 when the pressure falls below the lower limit pressure for use of the second bank, the accumulator in use is switched from the pressure accumulator 12 to the third bank (e.g., pressure accumulator 14).

[0068] When switching to the pressure accumulator 14, the valve control unit 65 outputs control signals to the valves 22, 24, and 26 via the communication control circuit 50 to control the opening and closing of each valve. Specifically, the valve 26 is opened, the valve 24 is closed, and the valve 22 is kept closed. This increases the pressure difference between the pressure accumulator 14 and the fuel tank 202, making it possible to maintain a high filling speed.

[0069] Then, the hydrogen gas stored in the pressure accumulator 14 due to the pressure difference between the 3rd bank (e.g., the pressure accumulator 14) and the fuel tank 202 moves toward the fuel tank 202, and the pressure in the fuel tank 202 gradually increases further as indicated by the dotted line Pt. Accordingly, the pressure in the pressure accumulator 14 (the graph indicated by "3rd") gradually decreases. Then, the 3rd bank fills the fuel tank 202 with hydrogen gas until the pressure in the fuel tank 202 reaches a target pressure Pg (e.g., 65 to 81 MPa).

[0070] As described above, hydrogen gas is filled into the fuel tank 202 in order from the first bank. Furthermore, the dispenser 30 measures the amount of hydrogen gas being filled into the fuel tank 202 of the FCV 200 during filling.

[0071] During this filling, in a filling amount calculation step (S112), the filling amount calculation unit 87 calculates a calculated filling amount Mc by subtracting the first weight N1 from the current weight Nt of hydrogen gas in the fuel tank 202. At the start of filling, Nt=N1, so the calculated filling amount Mc is 0. After filling starts, Nt=N2, so the calculated filling amount Mc after filling starts is the value obtained by subtracting the first weight N1 from the second weight N2 (i.e., Mc=N2-N1).

[0072] Similarly, during filling, as a filling amount measuring step (S114), the dispenser 30 measures the metered filling amount Mm of hydrogen gas using a Coriolis flowmeter 37. Specifically, the flowmeter 37 measures the mass flow rate at the moment of filling and generates a pulse for each minute flow rate unit, for example, 1 g. The pulse signal is output to the control circuit 43.

[0073] The control circuit 43 calculates the metered filling amount Mm by counting the pulses input from the start of filling and integrating the mass flow rate. The metered filling amount Mm is output to the control circuit 100, received by the dispenser information receiving unit 67, and stored in the memory device 84 together with the measurement time t. The metered filling amount Mm at the start of filling is 0.

[0074] Similarly, during filling, in a filling amount error calculation step (S116), the filling amount error calculation unit 89 calculates a filling amount error ΔM=Mm-Mc by subtracting the calculated filling amount Mc from the measured filling amount Mm measured at the same timing (time t) when the calculated filling amount Mc was calculated. At the start of filling, both the measured filling amount Mm and the calculated filling amount Mc are zero, so the filling amount error ΔM is also zero.

[0075] Similarly, during filling, in a determination step (S118), the determination unit 90 determines whether or not there is a malfunction in the flow meter 37 using the filling amount error ΔM. Specifically, the determination unit 90 determines whether or not the filling amount error ΔM is within a range of not less than a lower limit allowable value α1 and not more than an upper limit allowable value α2. If the filling amount error ΔM is not within a range of not less than a lower limit allowable value α1 and not more than an upper limit allowable value α2 (NO in S118), the process proceeds to an alarm output step (S120). If the filling amount error ΔM is within a range of not less than a lower limit allowable value α1 and not more than an upper limit allowable value α2 (YES in S118), the process proceeds to a determination step (S126).

[0076] In the alarm output step (S120), when it is determined that the flow meter 37 has failed, the output unit 74 outputs an alarm indicating the failure of the flow meter 37 to the dispenser 30 during filling of hydrogen gas. As an example of the alarm, the alarm lamp 34 indicating the failure of the flow meter 37 is turned on in the dispenser 30.

[0077] Similarly, during filling, in a determination step (S126), the determination unit 91 determines whether the pressure in the fuel tank 202 has reached the target pressure Pg. If the pressure in the fuel tank 202 has reached the target pressure Pg (YES in S126), the process proceeds to a filling stop processing step (S128). If the pressure in the fuel tank 202 has not reached the target pressure Pg (NO in S126), the process continues filling, and the process returns to the FCV information reception step (S102), and the steps from the FCV information reception step (S102) to the determination step (S118) are repeated during filling until the pressure in the fuel tank 202 reaches the target pressure Pg.

[0078] To summarize the above, the dispenser 30 repeatedly measures the metered filling amount Mm of hydrogen gas during filling by using the flow meter 37. At the same time, the filling amount calculation unit 87 repeatedly calculates the calculated filling amount Mc of hydrogen gas from the dispenser 30 to the fuel tank 202 using information on the pressure Pt, temperature Tt, and volume V of the fuel tank 202 during filling. The filling amount error calculation unit 89 repeatedly calculates the filling amount error ΔM by subtracting the calculated filling amount Mc from the metered filling amount Mm at the same timing as the calculated filling amount Mc is calculated.

[0079] During filling, the determination unit 90 compares the calculated filling volume Mc with the measured filling volume Mm, repeatedly determining whether or not the flow meter 37 has malfunctioned. That is, the determination unit 90 determines whether the filling volume error ΔM, calculated by subtracting the calculated filling volume Mc from the measured filling volume Mm, is greater than or equal to the lower limit allowable value α1 and less than or equal to the upper limit allowable value α2. If a malfunction occurs in the flow meter 37, the dispenser 30 outputs an alarm, for example, by turning on the alarm lamp 34. Note that during a short period of time during filling, large variations in the filling volume error ΔM may not occur. However, the control circuit 100 can detect sudden large changes (shifts) in the filling volume error ΔM.

[0080] In a filling stop processing step (S128), when the pressure in the fuel tank 202 reaches the target pressure Pg, the filling of hydrogen gas is stopped and the filling processing ends. Specifically, when the pressure measured by the pressure gauge 28 near the outlet of the dispenser 30 reaches the target pressure Pg, the dispenser control unit 64 determines that the pressure in the fuel tank 202 has reached the target pressure Pg, and closes the shut-off valves 36, 38 in the dispenser 30. In addition, the valve control unit 65 outputs control signals to the valves 22, 24, 26 via the communication control circuit 50, and controls each valve to close.

[0081] Next, in the recording and calculation step (S130), the recording and calculation unit 92 calculates the final measured filling amount Mmf at the end of filling, measured using the flow meter 37, and the final calculated filling amount Mcf at the end of filling, and stores these in the storage device 88 as actual data in association with the data on the date and time of filling. The final measured filling amount Mmf is the measured filling amount Mm at the end of filling, and is the mass flow rate integrated from the start to the end of filling. The final calculated filling amount Mcf is the calculated filling amount Mc at the end of filling, and is calculated by subtracting the first weight N1 from the second weight N2 at the end of filling. The recording and calculation unit 92 also calculates the final filling amount error ΔMf (=Mmf-Mcf) at the end of filling, and stores these in the storage device 88 as actual data in association with the data on the date and time of filling.

[0082] As a result, by repeatedly filling an unspecified number of FCVs 200 with hydrogen gas, multiple pieces of performance data are accumulated in the memory device 88. As a result, the memory device 88 stores multiple pieces of past performance data in which the final measured filling amount Mmf, the final calculated filling amount Mcf, and the final filling amount error ΔMf are associated with each other. Here, the case is shown in which the final filling amount error ΔMf is stored as multiple error values.

[0083] In the average error calculation step (S132), the average error calculation unit 93 reads out the final filling amount error ΔMf for each past hydrogen filling stored in the storage device 88, and calculates the average filling amount error ΔMave=ΣΔMf / number of fillings.

[0084] In the difference calculation step (S134), the error difference value calculation unit 94 calculates an error difference value Mx, which is the difference between the statistical value of multiple error values ​​based on multiple past performance data and the error value in the current hydrogen gas filling. Specifically, the error difference value calculation unit 94 calculates the error difference value Mx by subtracting the current final filling amount error ΔMf from the average filling amount error ΔMave.

[0085] In the judgment step (S136), the judgment unit 95 compares the statistical values ​​of multiple error values ​​based on multiple past actual data stored in the memory device 88 with the error value at the end of the current hydrogen gas filling, determines whether or not there is a malfunction in the flow meter 37, and outputs the result.

[0086] In this embodiment, the presence or absence of a malfunction of the flow meter 37 is determined depending on whether the error difference value Mx is within an allowable range. Specifically, the determination unit 95 determines whether the error difference value Mx is within a range of not less than a lower limit allowable value β1 and not more than an upper limit allowable value β2. If the error difference value Mx is not within a range of not less than the lower limit allowable value β1 and not more than an upper limit allowable value β2 (NO in S136), the process proceeds to an alarm output step (S138). If the error difference value Mx is within a range of not less than the lower limit allowable value β1 and not more than the upper limit allowable value β2 (YES in S136), the process ends.

[0087] In the alarm output step (S138), when it is determined that the flow meter 37 has failed, the output unit 74 outputs an alarm indicating the failure of the flow meter 37 to the dispenser 30 during filling of hydrogen gas. As an example of the alarm, the alarm lamp 34 indicating the failure of the flow meter 37 is turned on in the dispenser 30.

[0088] In the above example, the average filling amount error ΔMave is used as a statistical value of a plurality of error values ​​based on a plurality of past performance data, but this is not limited to this. For example, a median value may be used instead of the average value.

[0089] The lower limit allowable values ​​α1, β1 and the upper limit allowable values ​​α2, β2 may be set appropriately. The calculated filling amount using the PVT method is subject to deviation due to the expansion of the fuel tank 202 described above, so the difference between the measured filling amount and the calculated filling amount using the PVT method is usually not zero, and a certain offset amount exists. The lower limit allowable values ​​α1, β1 and the upper limit allowable values ​​α2, β2 may be set taking this into consideration.

[0090] As shown in Fig. 5, instead of the above-described determination step (S118) and alarm output step (S120), a determination step (S119), an alarm output step (S121), a determination step (S122), and an alarm output step (S123) may be performed as a modified example. Similarly, as shown in Fig. 6, instead of the above-described determination step (S136) and alarm output step (S138), a determination step (S140), an alarm output step (S141), a determination step (S142), and an alarm output step (S143) may be performed as a modified example.

[0091] In the determination step (S119), the determination unit 90 determines whether the current filling amount error ΔM is equal to or greater than the lower limit tolerance α1. If the filling amount error ΔM is equal to or greater than the lower limit tolerance α1 (YES in S119), the process proceeds to the determination step (S122). If the filling amount error ΔM is not equal to or greater than the lower limit tolerance α1 (NO in S119), the process proceeds to the warning output step (S121).

[0092] In the alarm output step (S121), if the filling amount error ΔM is not equal to or greater than the lower limit allowable value α1, the output unit 74 outputs alarm 1 indicating a failure of the flow meter 37 to the dispenser 30 while hydrogen gas is being filled. As an example of the alarm, the alarm lamp 34 indicating a failure of the flow meter 37 is turned on in the dispenser 30.

[0093] In the determination step (S122), the determination unit 90 determines whether the filling amount error ΔM is equal to or less than the upper limit allowable value α2. If the filling amount error ΔM is equal to or less than the upper limit allowable value α2 (YES in S122), the process proceeds to the determination step (S126). If the filling amount error ΔM is not equal to or less than the upper limit allowable value α2 (NO in S122), the process proceeds to the warning output step (S123).

[0094] In the alarm output step (S123), if the filling amount error ΔM is not equal to or less than the upper limit allowable value α2, the output unit 74 outputs alarm 2 indicating a failure of the flow meter 37 to the dispenser 30 while hydrogen gas is being filled. As an example of the alarm, the alarm lamp 35 indicating a failure of the flow meter 37 is turned on in the dispenser 30.

[0095] As described above, if the filling amount error ΔM is not equal to or less than the upper limit allowable value α2 in the judgment process during filling, the cause may be either a malfunction of the flow meter 37 or a leak in the piping from the flow meter 37 to the fuel tank 202, or both. On the other hand, if the filling amount error ΔM is not equal to or greater than the lower limit allowable value α1, it can be determined that there is a malfunction of the flow meter 37. Therefore, by dividing the judgment process into upper and lower limits and separating the contents of the alarm, it is possible to more easily identify the location of the malfunction.

[0096] 6, in the determination step (S140), the determination unit 95 determines whether the calculated error difference value Mx is equal to or greater than the lower limit allowable value β1. If the error difference value Mx is equal to or greater than the lower limit allowable value β1 (YES in S140), the process proceeds to the determination step (S142). If the error difference value Mx is not equal to or greater than the lower limit allowable value β1 (NO in S140), the process proceeds to the warning output step (S141).

[0097] In the alarm output step (S141), if the error difference value Mx is not equal to or greater than the lower limit allowable value β1, the output unit 74 outputs alarm 1 indicating a failure of the flow meter 37 to the dispenser 30 during filling of hydrogen gas. As an example of the alarm, the alarm lamp 34 indicating a failure of the flow meter 37 is turned on in the dispenser 30.

[0098] In the determination step (S142), the determination unit 95 determines whether the calculated error difference value Mx is equal to or less than the upper limit allowable value β2. If the error difference value Mx is equal to or less than the upper limit allowable value β2 (YES in S142), the process ends. If the error difference value Mx is not equal to or less than the upper limit allowable value β2 (NO in S142), the process proceeds to the warning output step (S143).

[0099] In the alarm output step (S143), if the error difference value Mx is not equal to or less than the upper limit allowable value β2, the output unit 74 outputs alarm 2 indicating a failure of the flow meter 37 to the dispenser 30 during filling of hydrogen gas. As an example of the alarm, the alarm lamp 35 indicating a failure of the flow meter 37 is turned on in the dispenser 30.

[0100] As described above, if the error difference value Mx is not equal to or less than the upper limit allowable value β2 in the determination process at the end of filling, the cause may be either a malfunction of the flow meter 37 or a leak in the piping from the flow meter 37 to the fuel tank 202, or both. On the other hand, if the error difference value Mx is not equal to or greater than the lower limit allowable value β1, it can be determined that there is a malfunction of the flow meter 37. Therefore, by dividing the determination process into upper and lower limits and separating the contents of the alarm, it is possible to more easily identify the location of the malfunction.

[0101] Note that the amount of hydrogen gas filled in each of the pressure accumulators 10, 12, and 14 has decreased due to the above-mentioned filling operation. Therefore, the pressure recovery mechanism 104 then restores the pressure in each of the pressure accumulators 10, 12, and 14. The pressure recovery mechanism 104 is composed of the compressor 40 and valves 21, 23, and 25, etc. First, the system control unit 58 selects a hydrogen gas supplier to be connected to the suction side of the compressor 40 from among a curdle, an intermediate pressure accumulator, a hydrogen trailer, or a hydrogen production device (none of which are shown). Then, under the control of the system control unit 58, the pressure recovery control unit 61 controls the pressure recovery mechanism 104 to restore the pressure in each of the pressure accumulators 10, 12, and 14.

[0102] Specifically, the system operates as follows. The accumulators of each bank used to fill the fuel tank 202 may be restored to pressure during filling. However, since there is not enough time to restore the pressure to the specified level, the accumulators must be restored after filling. Since the banks are switched in the order of 1st bank, 2nd bank, and 3rd bank, the accumulator 10 in the 1st bank is restored to pressure first. The valve control unit 60 opens the valve 21 from a state in which the valves 21, 23, and 25 are closed.

[0103] Then, the compressor control unit 62 drives the compressor 40 to compress and send out low-pressure (e.g., 0.6 MPa) hydrogen gas from the hydrogen gas supply source, and restores pressure to the pressure accumulator 10 by filling it with hydrogen gas until the pressure in the pressure accumulator 10 reaches a predetermined pressure P0 (e.g., 82 MPa).

[0104] Next, the valve control unit 60 closes the valve 21 and instead opens the valve 23. Then, the compressor control unit 62 drives the compressor 40 to compress and send out low-pressure (e.g., 0.6 MPa) hydrogen gas, and restores the pressure in the pressure accumulator 12 by filling it with hydrogen gas until the pressure in the pressure accumulator 12 reaches a predetermined pressure P0 (e.g., 82 MPa).

[0105] Next, the valve control unit 60 closes the valve 23 and instead opens the valve 25. Then, the compressor control unit 62 drives the compressor 40 to compress and send out low-pressure (e.g., 0.6 MPa) hydrogen gas, and restores the pressure in the pressure accumulator 14 by filling it with hydrogen gas until the pressure in the pressure accumulator 14 reaches a predetermined pressure P0 (e.g., 82 MPa).

[0106] As a result, even when the next FCV 200 arrives at the hydrogen station 102, hydrogen gas can be supplied in the same manner.

[0107] As described above, according to this embodiment, it is possible to continuously verify the accuracy of the flow meter 37. Therefore, it is possible to avoid performing the filling operation while still using a broken flow meter 37.

[0108] Next, another example of calculating the calculated filling amount Mc in the above-mentioned filling amount error calculation step (S116) will be described. In the above-mentioned filling amount error calculation step (S116), the capacity V of the fuel tank 202 used when calculating the calculated filling amount Mc is a predetermined value specific to the FCV 200, and the expansion rate of the fuel tank 202 is not particularly taken into consideration. Therefore, the calculated filling amount calculated using the PVT method will deviate due to the expansion of the fuel tank 202 described above, and the difference between the metered filling amount and the calculated filling amount calculated using the PVT method will not normally be zero, and a predetermined offset amount will exist.

[0109] After careful consideration, the inventors of the present application found that the deviation due to expansion of the fuel tank 202 is not always the same, and that the offset amount changes depending on the difference between the first pressure P1 at the start of filling and the second pressure P2 at the end of filling. Table 1 shows filling data obtained when hydrogen was filled multiple times at the hydrogen station 102.

[0110] [Table 1]

[0111] The filling data shown are the metered filling amount Mm, the first pressure P1, the second pressure P2, the first temperature T1, and the second temperature T2. The second pressure P2 and the second temperature T2 are data at the end of filling. The control circuit 100 also calculates the calculated filling amount Mc, subtracts the calculated filling amount Mc from the metered filling amount Mm, and calculates the filling amount error ΔM. The percentage error shown in Table 1 is 100 x (filling amount error ΔM / metered filling amount Mm).

[0112] FIG. 8 is a graph showing the relationship between the differential pressure at filling and the filling amount error for each filling data in Table 1. The horizontal axis of the graph shown in FIG. 8 is the differential pressure at filling [MPa], which is obtained by subtracting the first pressure P1 from the standard pressure Ps of the fuel tank 202 at the end of filling. The standard pressure Ps can be the average value of the second pressure P2 at the end of filling contained in multiple filling data obtained in the past. In addition, the filling amount error is calculated by assuming the average value of the second pressure P2 at the end of filling as the standard pressure Ps, and is plotted as shown in FIG. 8. Then, the coefficient of determination R of the approximation formula y is used. 2 Alternatively, a standard pressure Ps corrected so that P approaches 1 may be used. A known fitting method or the like may be used to correct the standard pressure Ps. Since the standard pressure Ps may vary depending on the outside temperature, the standard pressure Ps may be statistically calculated for each season with different outside temperatures. A specific value of the standard pressure Ps in the fuel tank in this example is 78 [MPa]. The vertical axis of the graph shown in FIG. 8 represents the filling amount error ΔM [kg].

[0113] As shown in Figure 8, the larger the differential pressure during filling, the larger the filling volume error ΔM, and the relationship shown by equation y was obtained, demonstrating a high correlation between the differential pressure during filling and the filling volume error. Note that equation y and the standard pressure Ps are values ​​suitable for a certain type of fuel tank, but if equation y is statistically calculated for each type of fuel tank or each vehicle model, it will be possible to accommodate a variety of FCVs 200 that arrive at the hydrogen station 102.

[0114] Therefore, based on the results shown in Figure 8, the calculated filling amount Mc is calculated using a value that takes into account the tank expansion rate as the tank capacity used in the PVT method. Specifically, the first function that indicates the first volume V1 of the fuel tank 202 in the filling amount calculation before the start of filling is V1 = Vs + (Vs × Ex) × (P1 / Ps), where Vs is the tank's standard capacity and Ex is the expansion rate. 3 In the first function, the correction amount of the tank capacity according to the expansion rate Ex is proportional to the cube of the first pressure P1. Also, the second function showing the second capacity V2 of the fuel tank 202 in the calculation of the filling amount after the start of filling is V2=Vs+(Vs×Ex)×(P2 / Ps). 3 In the second function, the correction amount of the tank capacity according to the expansion rate Ex is proportional to the cube of the second pressure P2. The expansion rate Ex and the standard capacity Vs are set according to the type of fuel tank 202, for example, with reference to the results shown in FIG. 8, and are stored in advance in the storage device 80. Also, instead of setting the first function and the second function as mathematical expressions, they may be stored in advance in the storage device 80 as a table according to parameters such as the first pressure P1 and the second pressure P2 of the fuel tank. The second function is expressed as V2=Vs+(Vs×Ex)×(P2 / Ps) 1 In other words, in the second function, the correction amount of the tank capacity according to the expansion rate Ex may be proportional to the second pressure P2.

[0115] Next, we will explain the flow meter determination method using the first volume V1 and the second volume V2 that take into account the expansion rate of the fuel tank 202. The outline of the hydrogen gas filling method, including the determination method, is almost the same as the flowcharts shown in Figures 5 and 6. The difference is that the first volume V1 and the second volume V2 that take into account the expansion rate of the fuel tank 202 are used in the process of calculating the calculated filling amount Mc used in the filling amount error calculation step (S116).

[0116] Specifically, the flow meter failure determination method of this embodiment includes the steps of: measuring the amount of hydrogen gas (measured filling amount Mm) to be filled into the fuel tank 202 using the flow meter 37 (S114); acquiring information on the pressure P and temperature T of the fuel tank 202 (S102); calculating the amount of hydrogen gas (calculated filling amount Mc) to be filled into the fuel tank 202 based on the acquired pressure P and temperature T and the capacity V of the fuel tank 202 taking into account the expansion rate Ex of the fuel tank 202 (S112); and determining whether or not the flow meter 37 has a failure using an error value (filling amount error ΔM) between the measured filling amount (measured filling amount Mm) and the calculated filling amount (calculated filling amount Mc) (S118).

[0117] As a result, in the step (S112) of calculating the filling amount, the calculated filling amount Mc is calculated from information on the pressure P, temperature T, and volume V of the fuel tank 202, because the tank expansion rate Ex is taken into consideration, improving the accuracy of the calculated filling amount Mc. In other words, the filling amount error ΔM between the measured filling amount Mm and the calculated filling amount Mc is small and the variation is reduced, improving the accuracy of malfunction determination of the flow meter 37. The filling amount error ΔM may be calculated at any timing after the start of filling. The filling amount error ΔM may be calculated at the end of filling, and the validity of the filling amount error ΔM may be evaluated at the end of filling. By evaluating the validity of the filling amount error ΔM at the end of filling, it is possible to determine whether the hydrogen gas filling amount is correctly measured for each filling. Alternatively, the filling amount error ΔM may be calculated during filling before the end of filling, and the validity of the filling amount error ΔM during filling may be evaluated. By evaluating the validity of the filling amount error ΔM during filling, any problems that occur during filling can be detected early.

[0118] The flowmeter failure determination method according to this embodiment includes an alarm output process (S120, S121, S123) for outputting the determination result. In the above example, an alarm lamp is turned on, but the type of alarm is not limited to this. In the alarm output process, a signal for operating an alarm unit (display panel, audio output, alarm lamp, etc.) of the dispenser 30 equipped with the flowmeter 37 may be output. In the alarm output process, a signal for notifying a monitor or a monitoring device monitoring at a remote location via a network may be output.

[0119] The calculated filling amount Mc is calculated by Mc=N2-N1 using a first weight N1=ρ(P1, T1)×V1 calculated from the first pressure P1, first temperature T1, and first volume V1 of the fuel tank 202 before the start of filling, and a second weight N2ρ(P2, T2)×V2 calculated from the second pressure P2, second temperature T2, and second volume V2 of the fuel tank 202 after the start of filling (S112). As described above, the first volume V1 and the second volume V2 of the fuel tank 202 can be calculated using the first and second functions represented by the mathematical expressions stored in the storage device 80. This enables failure determination by simple calculation based on information from the pressure gauge 206 and the thermometer 207 of the fuel tank 202.

[0120] Here, the first function and the second function are different. When the pressure inside the fuel tank 202 is relatively low before the start of filling, the first function can be used to accurately calculate the capacity taking into account the expansion rate of the fuel tank 202. On the other hand, when the pressure inside the fuel tank 202 is relatively high after the start of filling, the second function can be used to accurately calculate the capacity taking into account the expansion rate of the fuel tank 202. That is, the first function corrects the tank capacity according to the expansion rate based on the first pressure P1, while the second function corrects the tank capacity according to the expansion rate based on the second pressure P2. Therefore, the capacity of the fuel tank 202 can be calculated more accurately than if it were assumed that the correction amount according to the expansion rate is constant regardless of the pressure inside the tank. Furthermore, by incorporating the correction function that takes the expansion rate into the calculation formula for the calculated filling amount Mc, the filling amount error ΔM can be more appropriately calculated for each filling, thereby enabling a fault determination of the flow meter 37 to be performed simply and quickly. In other words, even if a plurality of past performance data required for calculating the average filling amount error ΔMave is not stored, a fault determination for the flow meter 37 can be performed with high accuracy.

[0121] The first volume V1 before the start of filling is a nonlinear first function (V1 = V + (V × Ex) × (P1 / Ps)) with respect to the first pressure P1. 3 ) as the calculation formula. The inventors of the present application have focused on the fact that the difference between the metered filling amount Mm and the calculated filling amount Mc (i.e., the filling amount error ΔM) is large when the fuel tank 202 is heavily filled (when the difference between the first pressure P1 and the second pressure P2 is large). The first pressure P1 of the fuel tank 202 depends on the amount of hydrogen gas consumed, which is in accordance with the distance traveled by the FCV 200 when it arrives at the hydrogen station 102, and therefore varies greatly depending on the situation. On the other hand, the second pressure P2 of the fuel tank 202 varies little depending on the situation. Therefore, a situation in which the fuel tank 202 is heavily filled can be said to be a situation in which the first pressure P1 of the fuel tank 202 is low. By using a nonlinear function with respect to the acquired information on the pressure inside the tank (first pressure P1) as the first function that takes the first pressure P1 into account, the capacity of the fuel tank 202 can be calculated more accurately than when it is assumed that the expansion rate increases in proportion to the pressure inside the tank. This is particularly effective when the first pressure P1 is low and the filling amount is large.

[0122] On the other hand, the second function that takes into account the second pressure P2 may be a nonlinear function or a linear function with respect to the acquired pressure inside the tank (second pressure P2). Because the second pressure P2 at the end of filling varies less depending on the situation than the first pressure P1, the fill volume error ΔM2 can be calculated accurately whether the value of (P2 / Ps) is corrected by raising it to the third power or by raising it to the first power. However, evaluation using actual data showed that correcting the second function that takes into account the second pressure P2 at the end of filling by raising it to the first power was preferable. Because the second pressure P2 during filling varies more depending on the situation than at the end of filling, it may be preferable to use a nonlinear function that corrects the value of (P2 / Ps) by raising it to the third power when calculating the second weight N2 during filling.

[0123] The control circuit 100 (specifically, the receiving unit 52) ​​may acquire information regarding the type of fuel tank 202 from the FCV 200. The control circuit 100 may acquire information regarding the vehicle model from the FCV 200 and identify the type of fuel tank 202 corresponding to the vehicle model. A table correlating vehicle models with fuel tank types may be stored in advance in the storage device 80. The first function and the second function regarding the first volume V1 or the second volume V2 may be set according to the type of fuel tank 202. This makes it possible to determine whether or not there is a malfunction in the flow meter 37 when filling hydrogen gas into fuel tanks of various vehicle models.

[0124] In this way, the failure determination method according to this embodiment makes it possible to verify the accuracy of the dispenser 30 in the hydrogen station 102, more specifically, the flow meter 37. Furthermore, the accuracy of the flow meter 37 can be verified continuously every time the FCV 200 is filled with hydrogen gas, without the need to close the hydrogen station 102.

[0125] In addition, the hydrogen filling device 500 of this embodiment is equipped with a measuring device (dispenser 30) that measures the amount of hydrogen gas (measured filling amount Mm) to be filled into the fuel tank 202 of the automobile using a flow meter 37, an acquisition unit (receiving unit 52) ​​that acquires information on the pressure P and temperature T of the fuel tank 202, a filling amount calculation unit 87 that calculates the filling amount (calculated filling amount Mc) of hydrogen gas to be filled into the fuel tank 202 from the measuring device (dispenser 30) based on the acquired pressure P and temperature T and the capacity V of the fuel tank 202 taking into account the expansion rate Ex of the fuel tank 202, and a judgment unit 90 that judges whether or not the flow meter 37 is malfunctioning using an error value (filling amount error ΔM) between the filling amount (measured filling amount Mm) measured using the flow meter 37 and the calculated filling amount (calculated filling amount Mc).

[0126] Although the present invention has been described above with reference to the above-mentioned embodiments, the present invention is not limited to the above-mentioned embodiments, and suitable combinations and substitutions of the configurations of the embodiments are also included in the present invention. Furthermore, it is possible to suitably rearrange the combinations and processing orders in the embodiments based on the knowledge of those skilled in the art, and to make modifications to the embodiments such as various design changes, and such modified embodiments are also included in the scope of the present invention. [Industrial Applicability]

[0127] The present invention relates to a technique for determining a malfunction of a measuring device provided in a hydrogen filling device. [Explanation of symbols]

[0128] 10,12,14 Accumulator, 30 Dispenser, 34,35 Alarm lamp, 37 Flow meter, 39 Display panel, 40 Compressor, 43 Control circuit, 50 Communication control circuit, 51 Memory, 52 Receiving unit, 54 Target pressure and temperature calculation unit, 58 System control unit, 64 Dispenser control unit, 67 Dispenser information receiving unit, 74 Output unit, 76 Monitor, 80 Storage device, 84 Storage device, 85 Gas weight calculation unit, 86 Judgment unit, 87 Filling amount calculation unit, 88 Storage device, 89 Filling amount error calculation unit, 90,91 Judgment unit, 92 Recording and calculation unit, 94 Error difference value calculation unit, 95 Judgment unit, 96 Setting unit, 100 Control circuit, 101 Multi-stage accumulator, 102 Hydrogen station, 200 FCV, 202 fuel tank, 204 on-board unit, 206 pressure gauge, 207 thermometer, 500 hydrogen filling system.

Claims

1. a measuring machine that measures the amount of hydrogen gas to be filled into the fuel tank of the automobile using a flow meter; an acquisition unit that acquires information on the pressure and temperature of the fuel tank; a fill amount calculation unit that calculates a fill amount of hydrogen gas to be filled into the fuel tank from the meter based on the acquired pressure and temperature and the capacity of the fuel tank taking into account the expansion rate of the fuel tank; a determination unit that determines whether or not the flow meter has a malfunction using an error value between the filling amount measured using the flow meter and the calculated filling amount; Equipped with The filling amount calculation unit calculating a corrected volume of the fuel tank using an expansion rate of the fuel tank and a pressure ratio, the pressure being the acquired pressure relative to a standard pressure of the fuel tank; A hydrogen filling device, characterized in that the amount of hydrogen gas to be filled into the fuel tank is calculated based on the acquired pressure and temperature and the corrected capacity of the fuel tank.

2. The filling amount calculation unit calculating a first weight of hydrogen gas in the fuel tank before the start of filling based on a first pressure, a first temperature, and a first volume of the fuel tank before the start of filling; calculating a second weight of hydrogen gas in the fuel tank after the start of filling based on a second pressure, a second temperature, and a second volume of the fuel tank after the start of filling; the first volume is calculated using the expansion rate and a first pressure ratio, which is the first pressure relative to the standard pressure; the second volume is calculated using the expansion rate and a second pressure ratio, which is the second pressure relative to the standard pressure; 2. The hydrogen filling device according to claim 1, wherein the calculated filling amount is calculated using the first weight and the second weight.

3. the first volume is calculated using a first function that is nonlinear with respect to the first pressure ratio; 3. The hydrogen filling device according to claim 2, wherein the second capacity is calculated using a second function that is linear or nonlinear with respect to the second pressure ratio.

4. the first function is proportional to the cube of the first pressure ratio; 4. The hydrogen filling device according to claim 3, wherein the second function is proportional to the second pressure ratio or proportional to the cube of the second pressure ratio.

5. the acquisition unit further acquires information regarding the type of the fuel tank; 5. The hydrogen filling device according to claim 3, wherein the first function and the second function are set according to the type of the fuel tank.

6. a step of measuring the amount of hydrogen gas to be filled into the fuel tank of the automobile using a flow meter; acquiring pressure and temperature information of the fuel tank; calculating a corrected volume of the fuel tank using an expansion rate of the fuel tank and a pressure ratio of the acquired pressure to a standard pressure of the fuel tank; calculating a filling amount of hydrogen gas to be filled into the fuel tank based on the acquired pressure and temperature and the corrected volume of the fuel tank; and determining whether or not there is a malfunction in the flow meter using an error value between the measured filling amount and the calculated filling amount.

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