Hydrogen filling device and flow meter failure determination method

Abstract

The invention provides a hydrogen filling device and a flow meter failure determination method. The flow meter malfunction determination method comprises the following steps: using a flow meter to measure the filling amount of hydrogen gas filled into a fuel tank of an automobile (S114); acquiring information of pressure and temperature of the fuel tank (S102); a step (S104, S112) for calculating the filling amount of hydrogen gas filled into the fuel tank on the basis of the acquired pressure and temperature and the capacity of the fuel tank taking into account the expansion rate of the fuel tank; and using an error value between the measured filling amount and the calculated filling amount to determine the presence or absence of a failure in the flow meter (S118).

Description

[0001] This application is a divisional application of the Chinese invention patent application with the application date of June 14, 2021, application number 202180041530.9 (PCT / JP2021 / 022481), and invention name “Flow meter fault judgment method and hydrogen filling device”. Technical Field

[0002] The present invention relates to a technology for determining a failure of a measuring device included in a hydrogen filling device. Background Art

[0003] In the past, a flow meter fault diagnosis method for a metering machine has been developed, which includes the following steps: using the error value between the metered filling amount at the end of filling measured by the flow meter based on multiple past performance data stored in a storage device and the calculated filling amount at the end of filling calculated using the pressure, temperature and capacity of the tank, and the error value between the metered filling amount at the end of filling measured by the flow meter at the end of this hydrogen filling and the calculated filling amount at the end of filling calculated using the pressure, temperature and capacity of the tank, to determine whether the flow meter has a fault and output the result (see patent document 1).

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent Application Laid-Open No. 2019-207196 Summary of the Invention

[0007] Problems to be solved by the invention

[0008] Furthermore, the difference between the measured filling amount and the calculated filling amount is caused by the expansion of the fuel tank and is typically not zero but rather exhibits an offset. Therefore, in the aforementioned fault diagnosis method, when the difference between the measured filling amount and the calculated filling amount is used as an error value to determine a fault, an allowable value is set that takes into account the specified offset. However, further research by the inventors of the present application has revealed that the expansion rate of a fuel tank is not necessarily constant but rather depends on the filling pressure.

[0009] The present invention has been made in view of the above circumstances, and one of its exemplary objects is to provide a new technology for improving the accuracy of failure determination in a flow meter.

[0010] Solutions for solving problems

[0011] A flow meter failure determination method according to a certain embodiment of the present invention includes the following steps: using a flow meter to measure the filling amount of hydrogen gas filled into a fuel tank of a vehicle; obtaining information on the pressure and temperature of the fuel tank; calculating the filling amount of hydrogen gas filled into the fuel tank based on the obtained pressure and temperature and the capacity of the fuel tank taking into account the expansion coefficient of the fuel tank; and using an error value between the measured filling amount and the calculated filling amount to determine whether the flow meter is faulty.

[0012] Effects of the Invention

[0013] According to one aspect of the present invention, it is possible to improve the accuracy of flow meter failure determination. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 This is a diagram showing an example of the configuration of a hydrogen filling system of a hydrogen filling station according to the present embodiment.

[0015] Figure 2 1 is a structural diagram showing an example of the internal structure of a control circuit that controls the entire hydrogen filling system according to the present embodiment.

[0016] Figure 3 This is a graph showing an example of changes in the percentage error of the flow meter relative to the number of fillings.

[0017] Figure 4 This is a graph showing another example of changes in the percentage error of the flow meter with respect to the number of fillings.

[0018] Figure 5 This is a flowchart showing a part of the process of the hydrogen gas filling method in this embodiment.

[0019] Figure 6 It is a flowchart showing the remaining steps of the hydrogen gas filling method in this embodiment.

[0020] Figure 7 This is a diagram for explaining a method of filling hydrogen gas using a multi-stage accumulator.

[0021] Figure 8 This is a graph showing the relationship between the pressure difference during filling and the filling amount error for each filling data in Table 1. DETAILED DESCRIPTION

[0022] First, the present invention is described. A flow meter failure determination method according to one embodiment of the present invention includes the following steps: measuring the amount of hydrogen gas filled into a fuel tank of a vehicle using a flow meter; acquiring information on the pressure and temperature of the fuel tank; calculating the amount of hydrogen gas filled into the fuel tank based on the acquired pressure and temperature and the capacity of the fuel tank taking into account the expansion coefficient of the fuel tank; and determining whether the flow meter is faulty using an error value between the measured amount and the calculated amount.

[0023] This method takes the fuel tank's expansion coefficient into account when calculating the filling amount, improving the accuracy of the filling amount calculation. In other words, the error between the measured filling amount and the calculated filling amount is reduced. Furthermore, this reduced deviation improves the accuracy of flowmeter failure detection.

[0024] The method may further include outputting the determination result. By outputting the determination result of whether the flow meter has a fault, it is possible to quickly understand whether the flow meter has a fault.

[0025] Alternatively, the method may further include the steps of calculating a first weight of hydrogen gas in the fuel tank before filling begins based on a first pressure, a first temperature, and a first capacity of the fuel tank before filling begins; and calculating a second weight of hydrogen gas in the fuel tank after filling begins based on a second pressure, a second temperature, and a second capacity of the fuel tank after filling begins. Alternatively, the calculated filling amount may be calculated using the first weight and the second weight. Using the first capacity before filling begins and the second capacity after filling begins, respectively, can improve the accuracy of filling amount calculation.

[0026] Alternatively, the first capacity may be calculated using the expansion rate and the first pressure, and the second capacity may be calculated using the expansion rate and the second pressure. By calculating the first capacity using the first pressure, the first weight before the start of filling can be calculated with high accuracy. In particular, when the pressure in the fuel tank is relatively low before the start of filling, the first capacity, which takes the expansion rate into account, can be calculated with high accuracy. Furthermore, by calculating the second capacity using the second pressure, the second weight after the start of filling can be calculated with high accuracy. In particular, when the pressure in the fuel tank is relatively high after the start of filling, the second capacity, which takes the expansion rate into account, can be calculated with high accuracy. This improves the accuracy of calculating the filling amount compared to a case where the capacity is kept constant regardless of the pressure in the fuel tank.

[0027] Alternatively, the first capacity may be calculated using a nonlinear first function for the first pressure, and the second capacity may be calculated using a linear or nonlinear second function for the second pressure. The first function and the second function may be represented by, for example, numerical expressions stored in a storage device. The inventors of the present application have focused on the following situation: when the filling amount is large (when the difference between the first pressure and the second pressure is large), the deviation between the measured filling amount and the calculated filling amount becomes large. In particular, when the first pressure is low, the filling amount becomes large. By calculating the first capacity using a nonlinear first function for the first pressure, the calculation accuracy of the first capacity can be improved compared to the case where the first capacity is calculated using a function proportional to the pressure in the fuel tank.

[0028] Alternatively, the method may further include a step of determining the type of fuel tank. Alternatively, the first function and the second function may be set according to the type of fuel tank. This allows flow meter failure detection when filling hydrogen gas in fuel tanks of various vehicle types.

[0029] Another embodiment of the present invention is a hydrogen filling device. The device includes: a metering device that uses a flow meter to measure the amount of hydrogen gas filled into a fuel tank of a vehicle; an acquisition unit that acquires information on the pressure and temperature of the fuel tank; a filling amount calculation unit that calculates the filling amount of hydrogen gas filled into the fuel tank from the metering device based on the acquired pressure and temperature and the capacity of the fuel tank taking into account the expansion coefficient of the fuel tank; and a determination unit that uses an error value between the filling amount measured by the flow meter and the calculated filling amount to determine whether the flow meter has a malfunction.

[0030] This method takes the fuel tank's expansion rate into account when calculating the filling amount, improving the accuracy of the filling amount calculation. In other words, the error between the measured filling amount and the calculated filling amount is reduced. Furthermore, this reduced deviation improves the accuracy of flowmeter failure detection.

[0031] In addition, any combination of the above structural elements, or any expression of the present invention in the form of a method, device, system, etc., is also valid as a mode of the present invention. In addition, modes obtained by appropriately combining the above elements are also included in the scope of the technical solutions claimed for patent protection by the patent application of this case.

[0032] Below, the present invention is described with reference to the accompanying drawings based on a preferred embodiment. The embodiments are not intended to limit the present invention but to illustrate, and all the features and combinations thereof described in the embodiments are not necessarily essential features of the present invention. The same or equivalent structural elements, components, and processes shown in the drawings are marked with the same figure numerals, and repeated descriptions are appropriately omitted. In addition, the scales and shapes of the various parts shown in the figures are conveniently set for ease of description, and are not to be interpreted as limiting unless otherwise specified. In addition, even for the same components, the scales and the like may sometimes be slightly different between the drawings. In addition, when terms such as "first" and "second" are used in this specification or claims, unless otherwise specified, they do not indicate any order or importance, but are used to distinguish a certain structure from other structures.

[0033] First, an example of a hydrogen filling system to which the present invention can be applied will be described. Figure 1 : is a diagram showing an example of the configuration of a hydrogen filling system of a hydrogen filling station according to this embodiment. Figure 1 In the embodiment, hydrogen filling system 500 is arranged in hydrogen filling station 102. Hydrogen filling system (hydrogen filling device) 500 includes multi-stage accumulator 101, dispenser (metering device) 30, compressor 40, and control circuit 100. Multi-stage accumulator 101 is composed of multiple accumulators 10, 12, and 14 with different lower limit pressures.

[0034] exist Figure 1 In the example, a multi-stage accumulator 101 is composed of three accumulators 10, 12, and 14. For example, the accumulator 10 functions as a first pressure accumulator (Japanese: 1st bank) with a low lower limit pressure, the accumulator 12 functions as a second pressure accumulator (Japanese: 2nd bank) with a medium lower limit pressure, and the accumulator 14 functions as a third pressure accumulator (Japanese: 3rd bank) with a high lower limit pressure. However, it is not limited to this. Each accumulator used as the first to third pressure accumulators can be replaced as needed. In addition, a container (Japanese: カードル), an intermediate accumulator, or a hydrogen manufacturing device (none of which are shown in the figure) is also configured in the hydrogen filling station 102. A hydrogen trailer (not shown) that delivers filled hydrogen arrives at the hydrogen filling station 102.

[0035] exist Figure 1 In the embodiment, the suction side of the compressor 40 is connected to the above-mentioned manifold, intermediate accumulator, filling tank of the hydrogen trailer, or hydrogen production equipment through piping.

[0036] The discharge side of the compressor 40 is connected to the accumulator 10 via a valve 21 and a pipe. Similarly, the discharge side of the compressor 40 is connected to the accumulator 12 via a valve 23 and a pipe. Similarly, the discharge side of the compressor 40 is connected to the accumulator 14 via a valve 25 and a pipe.

[0037] Accumulator 10 is connected to distributor 30 via a valve 22 and piping. Accumulator 12 is connected to distributor 30 via a valve 24 and piping. Accumulator 14 is connected to distributor 30 via a valve 26 and piping. In this manner, accumulators 10, 12, and 14 constituting multi-stage accumulator 101 are commonly connected to distributor 30.

[0038] exist Figure 1 In the embodiment, a shutoff valve 36, a flow control valve 33, a flow meter 37, a cooler 32 (precooler), a shutoff valve 38, an emergency disconnect coupler 41, and a control circuit 43 are arranged within the distributor 30. A nozzle 44 extending outward from the distributor 30 is arranged within the distributor 30. The distributor 30 delivers hydrogen gas (hydrogen fuel) supplied from the multi-stage accumulator 101 to the cooler 32 via the shutoff valve 36, the flow control 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 accumulator 101 is controlled by the flow control valve 33.

[0039] The distributor 30 measures the filling amount of hydrogen gas filled from the multi-stage accumulator 101 to the fuel tank 202 of the FCV (fuel cell vehicle) 200. Specifically, the mass flow rate of the hydrogen gas filled into the fuel tank 202 is measured by the flow meter 37. In this embodiment, as the flow meter 37, for example, a Coriolis mass flow meter is used. The control circuit 43 accumulates the mass flow rate measured by the flow meter 37 to measure the filling amount. The filling amount measured using the flow meter 37 is also referred to as the "metered filling amount". In addition, the filled hydrogen gas is cooled to, for example, -40°C by the cooler 32. The cooled hydrogen gas is filled into the fuel tank 202 via the shut-off valve 38, the emergency disconnect connector 41 and the nozzle 44 using the pressure difference.

[0040] The control circuit 43 is configured to be able to communicate with the onboard device 204 in the FCV 200. For example, the control circuit 43 can wirelessly communicate with the onboard device 204 using infrared rays. The control circuit 43 is connected to the control circuit 100 for controlling the entire hydrogen filling system 500. A display panel 39 is disposed on the outer surface of the dispenser 30. Warning lights 34 and 35 are disposed within the display panel 39.

[0041] exist Figure 1 In hydrogen filling system 500, multiple pressure gauges are located at various locations in the hydrogen fuel flow path, from multi-stage accumulator 101 to the outlet of distributor 30. Specifically, pressure gauge 11 measures the pressure within accumulator 10. Pressure gauge 13 measures the pressure within accumulator 12. Pressure gauge 15 measures the pressure within accumulator 14. Pressure gauge 27 measures the pressure near the inlet of distributor 30. Pressure gauge 28 measures the pressure near the outlet of distributor 30.

[0042] exist Figure 1 In the example shown, 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 on the secondary side of cooler 32, i.e., near emergency disconnect coupler 41. The pressure data measured by each pressure gauge is output to control circuit 100 either constantly or at a predetermined sampling interval (e.g., 10 milliseconds to several seconds). In other words, control circuit 100 monitors the pressure measured by each pressure gauge constantly or at a predetermined sampling interval.

[0043] The pressure of the fuel tank 202 is measured by a pressure gauge 206 mounted on the FCV 200. As will be described later, while communication between the vehicle-mounted device 204 and the control circuit 43 is established, the pressure of the fuel tank 202 is monitored constantly or at predetermined sampling intervals (eg, 10 milliseconds to several seconds).

[0044] The temperature of the hydrogen gas near the outlet of the distributor 30 is measured by thermometer 29. The temperature of the secondary side of the cooler 32, for example, near the emergency disconnect coupler 41, is also measured by thermometer 31. Furthermore, the temperature of the outside air near the distributor 30 is measured by thermometer 31. The temperature data measured by each thermometer is output to the control circuit 100 either constantly or at a predetermined sampling interval (e.g., 10 milliseconds to several tens of seconds). In other words, the control circuit 100 monitors the temperature measured by each thermometer constantly or at a predetermined sampling interval.

[0045] The temperature of the fuel tank 202 is measured by a thermometer 207 mounted on the FCV 200. As will be described later, the temperature of the fuel tank 202 is monitored constantly or at predetermined sampling intervals (eg, 10 milliseconds to several seconds) while communication between the vehicle-mounted device 204 and the control circuit 43 is established.

[0046] The hydrogen gas stored in the tank of the container, intermediate accumulator, or hydrogen trailer is supplied to the suction side of the compressor 40 in a state where it is reduced in pressure to a low pressure (e.g., 0.6 MPa) by respective regulators (not shown) controlled by the control circuit 100. Similarly, the hydrogen gas produced by the hydrogen manufacturing device is supplied to the suction side of the compressor 40 in a state of low pressure (e.g., 0.6 MPa). Under the control of the control circuit 100, the compressor 40 compresses the hydrogen gas supplied at a low pressure and supplies the compressed hydrogen gas to each accumulator 10, 12, 14 of the multi-stage accumulator 101. The compressor 40 compresses the hydrogen gas until the pressure in each accumulator 10, 12, 14 reaches a specified high pressure (e.g., 82 MPa). In other words, the compressor 40 compresses the hydrogen gas until the secondary side pressure P on the ejection side reaches 0. OUT Until it reaches a predetermined high pressure (e.g., 82 MPa).

[0047] The control circuit 100 determines which of the container, intermediate accumulator, hydrogen trailer, and hydrogen production equipment is the source of hydrogen gas supplied to the intake side of the compressor 40. Similarly, the control circuit 100 controls the opening and closing of valves 21, 23, and 25 to determine which of the accumulators 10, 12, and 14 the compressor 40 supplies hydrogen gas to. The control circuit 100 can also control the compressor 40 to supply hydrogen gas to two or more accumulators simultaneously.

[0048] In the above example, the pressure P of hydrogen gas supplied to the suction side of the compressor 40 is shown. IN The pressure may be reduced to a predetermined low pressure (e.g., 0.6 MPa), but the present invention is not limited thereto. For example, when hydrogen gas stored in a container, an intermediate accumulator, or a hydrogen trailer is supplied to the suction side of the compressor 40, the hydrogen gas may not be depressurized, but may be depressurized to a pressure higher than the predetermined low pressure (e.g., 0.6 MPa).

[0049] The hydrogen gas accumulated in the multi-stage pressure accumulator 101 is cooled by the cooler 32 in the distributor 30 and is supplied from the distributor 30 to the FCV 200 .

[0050] Figure 2 : is a structural diagram showing an example of the internal structure of a control circuit that controls the entire hydrogen filling system involved in this embodiment. Figure 2 In the control circuit 100, a communication control circuit 50, a memory 51, a receiving unit 52, a target pressure / temperature calculation unit 54, a system control unit 58, a recovery pressure control unit 61, a supply control unit 63, a pressure accumulator pressure receiver 66, a distributor 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 calculator 94, a determination unit 95, a setting unit 96, a monitor 76, and storage devices 80, 84, and 88, such as a magnetic disk drive, are arranged. The recovery pressure control unit 61 includes a valve control unit 60 and a compressor control unit 62. The supply control unit 63 includes a distributor control unit 64 and a valve control unit 65.

[0051] Each unit, such as the receiving unit 52, the target pressure / temperature calculation unit 54, the system control unit 58, the recovery pressure 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 pressure accumulator 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 calculation unit 94, the determination unit 95, and the setting unit 96, includes a processing circuit. This processing circuit includes a circuit, a computer, a processor, a circuit board, or a semiconductor device. For example, a CPU (Central Processing Unit), an FPGA (Field-Programmable Gate Array), or an ASIC (Application Specific Integrated Circuit) may be used as the processing circuit.

[0052] The above-mentioned components may use a common processing circuit (the same processing circuit), or may use different processing circuits (separate processing circuits). The input data required by the above-mentioned components or the results calculated by the above-mentioned components are stored in the memory 51 at each time.

[0053] Storage device 80 stores FCV information such as the pressure P, temperature T, and capacity V of fuel tank 202 received from FCV 200. Storage device 80 also stores a conversion table 81 that indicates the correlation between the weight N of hydrogen gas in fuel tank 202 corresponding to the FCV information and filling information such as the target pressure Pg and target temperature Tg of hydrogen gas to be filled into fuel tank 202. Storage device 80 also stores a correction table 82 used to correct the results obtained from conversion table 81.

[0054] The accumulator pressure receiving unit 66 constantly receives the pressures measured by the pressure gauges 11, 13, and 15 within the accumulator 10, or at a predetermined sampling cycle, and stores the pressures along with the time of receipt in the storage device 84. The distributor information receiving unit 67 constantly receives the pressures measured by the pressure gauges 27 and 28 within the distributor 30, or at a predetermined sampling cycle, and stores the pressures along with the time of receipt in the storage device 84. The distributor information receiving unit 67 constantly receives the temperature measured by the thermometer 29 within the distributor 30, or at a predetermined sampling cycle, and stores the temperature along with the time of receipt in the storage device 84.

[0055] As described above, the amount (mass flow rate) of hydrogen gas being filled into the fuel tank 202 is measured using the flow meter 37. The flow meter 37 measures the mass flow rate at the moment of filling, generating pulses in microscopic flow units, such as per 1g. The pulse signal is output to the control circuit 43. The control circuit 43 counts the number of pulses generated since the start of filling, integrating the mass flow rate and thereby measuring the measured filling amount Mm.

[0056] During filling, the current value of the measured filling volume Mm is displayed on the display panel 39 disposed on the outer surface of the dispenser 30 while changing with time, and is also output to the control circuit 100. The measured filling volume Mm is the raw data for the price paid by the consumer. In other words, the price paid by the consumer (user) is the amount obtained by multiplying the displayed measured filling volume Mm by the price of hydrogen per unit filling volume. Therefore, the measurement accuracy of the flow meter 37 is important.

[0057] As described above, the FCV 200 outputs FCV information such as the pressure P, temperature T, and capacity V of the fuel tank 202. These values ​​can also be displayed on the display panel 39. Specifically, the values ​​of the pressure Pt and temperature Tt of the fuel tank 202 at the current time t can also be displayed on the display panel 39 while changing over time.

[0058] The control circuit 100 calculates the density ρ(P, T) of the hydrogen gas within the fuel tank 202 using the pressure P and temperature T of the fuel tank 202 and the inherent compressibility of hydrogen. The control circuit 100 multiplies the density ρ(P, T) by the capacity V of the fuel tank 202 to calculate the weight N = ρ(P, T) × V of the hydrogen gas within the fuel tank 202. As the weight N, the control circuit 100 calculates a first weight N1 before filling begins and a second weight N2 after filling begins. The first weight N1 is calculated by multiplying the density ρ(P1, T1), calculated based on the first pressure (initial pressure) P1 and the first temperature (initial temperature) T1 of the fuel tank 202 before filling begins, by the capacity V (that is, N1 = ρ(P1, T1) × V). The second weight N2 is calculated by multiplying the density ρ(P2, T2), calculated based on the second pressure P2 and the second temperature T2 after filling begins, by the capacity V (that is, N2 = ρ(P2, T2) × V). Here, “after the start of filling” includes a timing of an arbitrary time t during the filling period and a timing when the filling is completed.

[0059] The control circuit 100 calculates the hydrogen filling amount Mc by subtracting the first weight N1 from the second weight N2 (that is, 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 inherent compressibility of hydrogen, and is calculated using the PVT method (volume method). The calculated filling amount Mc corresponds to the weight of hydrogen filled into the fuel tank 202 after filling begins.

[0060] The calculated filling amount Mc can be used to evaluate the validity of the measured filling amount Mm measured by the flow meter 37. Therefore, the percentage error of the flow meter 37 is evaluated by dividing the filling amount error ΔM obtained by subtracting the calculated filling amount Mc from the measured filling amount Mm by the calculated filling amount Mc and multiplying the result by 100.

[0061] Figure 3 : is a graph showing an example of the change in the percentage error of the flow meter 37 with respect to the number of fillings. Figure 3 In the example of , an example of a case where no abnormality occurs in the flow meter 37 during the verification period is shown. Figure 3 In FIG. 3 , the vertical axis shows the percentage error of the flow meter 37 and the horizontal axis shows the number of fillings. Figure 3 As shown in FIG, by using a large number of filling results to verify the size of the percentage error based on the timing of the filling number, it is possible to continuously confirm the change over time of the flow meter 37. Figure 3 As a result, it can be seen that the percentage error of flow meter 37 is stably converging within a range of Δ2. Furthermore, the reason why the percentage error of flow meter 37 is not zero but is offset by Δ1 to the positive side is that the fuel tank 202 expands due to filling, resulting in a deviation in the calculation results of the PVT method due to this expansion.

[0062] Figure 4 FIG. 1 is another example of a graph showing the change in the percentage error of a flow meter relative to the number of fillings. Figure 4 In the example of FIG, an example of a case where an abnormality occurs in the flow meter 37 during the verification period is shown. Figure 4 In FIG, the vertical axis shows the percentage error of the flow meter 37 and the horizontal axis shows the number of fillings. Figure 4 In the example, it can be seen that as the number of fillings increases, the deviation of the percentage error of the flow meter 37 becomes larger. At the two filling times of A and B, the value changes significantly (shifts) in a step-like manner. The value shifts in the same way. Figure 4 In the example of , the positive side offset shifts to the negative side. In this way, a large change in the percentage error of the flow meter 37 in a short period of time indicates that a major abnormality (failure) other than the change over time has occurred in the flow meter 37.

[0063] First, the deviation of the percentage error of the flow meter 37 can only be determined through the continuous verification based on a large number of filling times in this embodiment. On the other hand, in the previous gravimetric method, only about four measurements were usually made. Therefore, in the previous gravimetric method, it was difficult to determine whether the deviation had increased. In addition, for sudden large changes (displacements) in the percentage error of the flow meter 37, the continuous verification of this embodiment can determine the time point when the percentage error of the flow meter 37 changed (displaced) significantly, thereby detecting an abnormality in the flow meter 37.

[0064] From the above results, it can be seen that it is useful to compare the calculated filling amount Mc with the measured filling amount Mm. Therefore, in this embodiment, the error value between the calculated filling amount Mc and the measured filling amount Mm is used to perform fault diagnosis of the flow meter 37. Figure 3 and Figure 4 In the example of , the percentage error is used for the explanation, but the error value that can be verified is not limited to this. Next, the case where the difference between the calculated filling amount Mc and the measured filling amount Mm, that is, the filling amount error ΔM=Mm-Mc, is used as the error value is explained.

[0065] Figure 5 This is a flowchart showing a part of the process of the hydrogen gas filling method in this embodiment. Figure 6 It is a flowchart showing the remaining steps of the hydrogen gas filling method in this embodiment.

[0066] exist Figure 5 and Figure 6 In the present embodiment, the hydrogen filling method implements a judgment process (S100), an FCV information receiving process (S102), a gas weight calculation process (S104), a judgment process (S106), an initial weight setting process (S108), a filling process (S110), a filling quantity calculation process (S112), a filling quantity measurement process (S114), a filling quantity error calculation process (S116), a judgment process (S118), an alarm output process (S120), a judgment process (S126), a filling stop processing process (S128), a recording / calculation process (S130), an average error calculation process (S132), a difference calculation process (S134), a judgment process (S136) and an alarm output process (S138).

[0067] When the FCV 200 arrives at the hydrogen refueling station 102, the operator of the hydrogen refueling station 102 or the user of the FCV 200 connects (fits) the nozzle 44 of the dispenser 30 to the receiving port (receptacle) of the fuel tank 202 of the FCV 200 and secures it. The operator or user then presses a start filling button (not shown) on the display panel 39 of the dispenser 30.

[0068] In a determination step (S100), the control circuit 43 determines whether the operator or user has pressed the Start Filling button. If the Start Filling button has been pressed (S100: Yes), the process proceeds to the FCV information receiving step (S102). If the Start Filling button has not been pressed (S100: No), the process does not proceed to the next step. When the Start Filling button is pressed, communication is established between the vehicle-mounted device 204 and the control circuit 43 (repeater).

[0069] In the FCV information receiving step (S102), the receiving unit 52 receives FCV information such as the current (time t) temperature Tt and pressure Pt of the fuel tank 202, and the capacity V of the fuel tank 202 from the FCV 200. Specifically, the operation is as follows. When communication is established between the onboard device 204 and the control circuit 43 (repeater), the FCV information (tank information) is output (sent) from the onboard device 204 in real time.

[0070] The FCV information is relayed by the control circuit 43 included in the distributor 30 and then transmitted to the control circuit 100, which controls the entire hydrogen filling system 500. Within the control circuit 100, the receiver 52 receives the FCV information via the communication control circuit 50. While communication is established between the onboard device 204 and the control circuit 43, the FCV information is monitored constantly or at predetermined sampling intervals (e.g., 10 milliseconds to several seconds). The received FCV information is stored in the storage device 80 along with the time of receipt.

[0071] In the gas weight calculation step ( S104 ), the gas weight calculation unit 85 calculates the weight Nt of the hydrogen gas filled in the fuel tank 202 at the current time (time t) using the PVT method. Specifically, the gas weight calculation unit 85 calculates the density ρ(Pt, Tt) of the hydrogen gas using the pressure Pt and temperature Tt of the fuel tank 202 at the current time, as well as the inherent compressibility of hydrogen. The gas weight calculation unit 85 multiplies the density ρ(Pt, Tt) by the capacity V of the fuel tank 202 to calculate the weight Nt = ρ(Pt, Tt) × V of the hydrogen gas in the fuel tank 202 at the current time.

[0072] As a 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 (S106: "Yes"), 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 later determination process since the start of this filling (S106: "No"), the process continues with the filling step (S110) described later and proceeds to the filling amount calculation step (S112).

[0073] As the initial weight setting step (S108), if this is the first determination process in the determination step (S106), that is, if it is before the start of filling, the setting unit 96 sets the calculated hydrogen gas weight Nt as the first weight N1. The first weight N1 can be calculated using the FCV information (first temperature T1 and first pressure P1) before the start of filling as N1 = ρ(P1, T1) × V.

[0074] In the filling process ( S110 ), the target pressure / temperature calculation unit 54 first 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 volume V of the fuel tank 202, as well as the outside air temperature T'. Furthermore, the target pressure / temperature calculation unit 54 reads the correction table 82 from the storage device 80 to correct the values ​​obtained from the conversion table 81. The correction table 82 is used to correct the values ​​obtained from the conversion table 81 using correction values ​​set based on experimental or simulation results, if the results obtained using only the data from the conversion table 81 have large errors. The calculated target pressure Pg and target temperature Tg are output to the system control unit 58.

[0075] Next, filling of the fuel tank 202 with hydrogen gas starts from the multi-stage accumulator 101 via the distributor 30 .

[0076] Figure 7 This is a diagram for explaining a method of filling hydrogen gas using a multi-stage accumulator. Figure 7 The vertical axis shows pressure, and the horizontal axis shows time. When FCV 200 performs differential pressure filling of hydrogen, each accumulator 10, 12, and 14 of the multi-stage accumulator 101 is typically pre-pressurized to the same pressure P0 (e.g., 82 MPa). Meanwhile, at time t0, which is the start of filling, the fuel tank 202 reaches a first pressure P1. The following describes the process of starting to fill the fuel tank 202 with hydrogen from this state.

[0077] First, hydrogen gas is filled from the first pressure accumulator (e.g., accumulator 10) into fuel tank 202. Specifically, the following operations are performed. Under the control of system control unit 58, supply control unit 63 controls supply unit 106 to supply hydrogen gas from accumulator 10 to fuel tank 202 of FCV 200. Specifically, system control unit 58 controls dispenser control unit 64 and valve control unit 65. Dispenser control unit 64 communicates with control circuit 43 of dispenser 30 via communication control circuit 50 to control the operation of dispenser 30.

[0078] Specifically, the control circuit 43 first adjusts the opening of the flow control valve within the distributor 30 to open the shutoff valves 36 and 38 within the distributor 30. Furthermore, the valve control unit 65 outputs control signals to valves 22, 24, and 26 via the communication control circuit 50, thereby controlling the opening and closing of each valve. Specifically, valve 22 is opened, while valves 24 and 26 remain closed. This causes hydrogen gas to be supplied from the accumulator 10 to the fuel tank 202. Due to the pressure difference between the accumulator 10 and the fuel tank 202, the hydrogen gas stored in the accumulator 10 moves toward the fuel tank 202 at a filling rate regulated by the flow control valve, gradually increasing the pressure in the fuel tank 202 as indicated by the dotted line Pt. As this pressure increases, the pressure in the accumulator 10 (the curve indicated by "First") gradually decreases. Then, at time t1, when the pressure falls below the lower limit of use for the first accumulator, the accumulator in use is switched from the accumulator 10 to the second accumulator (e.g., the accumulator 12).

[0079] When switching to the accumulator 12, the valve control unit 65 outputs control signals to valves 22, 24, and 26 via the communication control circuit 50, thereby controlling the opening and closing of each valve. Specifically, valve 24 is opened, valve 22 is closed, and valve 26 remains closed. This increases the pressure difference between the accumulator 12 and the fuel tank 202, thereby maintaining a high filling speed.

[0080] The pressure differential between the second accumulator (e.g., accumulator 12) and fuel tank 202 then causes the hydrogen gas stored in accumulator 12 to move toward fuel tank 202, causing the pressure in fuel tank 202 to gradually rise, as indicated by the dashed line Pt. This pressure in accumulator 12 (the curve indicated by "Second") gradually decreases. At time t2, when the pressure falls below the lower limit of the second accumulator's operating pressure, the accumulator in use is switched from accumulator 12 to the third accumulator (e.g., accumulator 14).

[0081] When switching to the accumulator 14, the valve control unit 65 outputs control signals to valves 22, 24, and 26 via the communication control circuit 50, thereby controlling the opening and closing of each valve. Specifically, valve 26 is opened, valve 24 is closed, and valve 22 remains closed. This increases the pressure difference between the accumulator 14 and the fuel tank 202, thereby maintaining a high filling speed.

[0082] The pressure differential between the third accumulator (e.g., accumulator 14) and fuel tank 202 then causes the hydrogen gas stored in accumulator 14 to move toward fuel tank 202, causing the pressure in fuel tank 202 to gradually rise, as indicated by the dashed line Pt. Simultaneously, the pressure in accumulator 14 (the curve indicated by "Third") gradually decreases. The third accumulator is then filled with hydrogen gas until the pressure in fuel tank 202 reaches the target pressure Pg (e.g., 65-81 MPa).

[0083] As described above, hydrogen gas is sequentially filled into the fuel tank 202 from the first pressure accumulator. When hydrogen gas is filled into the fuel tank 202 of the FCV 200, the dispenser 30 measures the amount of hydrogen gas filled during the filling period.

[0084] During this filling process, as a filling amount calculation step (S112), the filling amount calculation unit 87 calculates the calculated filling amount Mc by subtracting the first weight N1 from the current weight Nt of the hydrogen gas in the fuel tank 202. At the start of filling, Nt = N1, so the calculated filling amount Mc is 0. Furthermore, after the start of filling, Nt = N2, so the calculated filling amount Mc after the start of filling is the value obtained by subtracting the first weight N1 from the second weight N2 (that is, Mc = N2 - N1).

[0085] Similarly, during the filling process, as part of the filling amount measurement step ( S114 ), the dispenser 30 uses a Coriolis flowmeter 37 to measure the measured filling amount Mm of hydrogen gas. Specifically, the flowmeter 37 measures the mass flow rate at the moment of filling and generates a pulse for each minute flow rate unit, such as 1g. The pulse signal is output to the control circuit 43.

[0086] The control circuit 43 counts pulses input from the start of filling and integrates the mass flow rate to calculate the measured filling amount Mm. The measured filling amount Mm is output to the control circuit 100, received by the dispenser information receiving unit 67, and stored in the storage device 84 along with the measurement time t. The measured filling amount Mm at the start of filling is 0.

[0087] Similarly, during filling, as a filling amount error calculation step (S116), the filling amount error calculation unit 89 calculates the filling amount error ΔM = Mm - Mc by subtracting the calculated filling amount Mc from the measured filling amount Mm measured at the same time (time t) as the calculated filling amount Mc. 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.

[0088] Similarly, during the filling process, the determination unit 90 uses the filling amount error ΔM to determine whether the flowmeter 37 is faulty as part of a determination step ( S118 ). Specifically, the determination unit 90 determines whether the filling amount error ΔM is within a range of greater than or equal to the lower allowable value α1 and less than or equal to the upper allowable value α2 . If the filling amount error ΔM is not within the range of greater than or equal to the lower allowable value α1 and less than or equal to the upper allowable value α2 ( S118 : No ), the process proceeds to an alarm output step ( S120 ). If the filling amount error ΔM is within the range of greater than or equal to the lower allowable value α1 and less than or equal to the upper allowable value α2 ( S118 : Yes ), the process proceeds to a determination step ( S126 ).

[0089] In the alarm output step (S120), if the flow meter 37 is determined to be faulty, the output unit 74 outputs an alarm indicating the failure of the flow meter 37 to the dispenser 30 during hydrogen filling. 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.

[0090] Similarly, during the filling period, the determination unit 91 determines whether the pressure of the fuel tank 202 has reached the target pressure Pg as a determination step (S126). If the pressure of the fuel tank 202 has reached the target pressure Pg (S126: "Yes"), the process proceeds to the filling stop processing step (S128). If the pressure of the fuel tank 202 has not reached the target pressure Pg (S126: "No"), the filling process continues and returns to the FCV information receiving step (S102). During the filling period, the processes from the FCV information receiving step (S102) to the determination step (S118) are repeated until the pressure of the fuel tank 202 reaches the target pressure Pg.

[0091] As described above, the dispenser 30 repeatedly measures the measured filling amount Mm of hydrogen gas during the filling period using the flowmeter 37. Simultaneously, 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 the filling period. The filling amount error calculation unit 89 repeatedly calculates the filling amount error ΔM, obtained by subtracting the calculated filling amount Mc from the measured filling amount Mm, at the same timing as calculating the calculated filling amount Mc.

[0092] During the filling period, the determination unit 90 compares the calculated filling amount Mc with the measured filling amount Mm to repeatedly determine whether the flowmeter 37 has a malfunction. Specifically, the determination unit 90 determines whether the filling amount error ΔM, obtained by subtracting the calculated filling amount Mc from the measured filling amount Mm, is within a range between a lower limit tolerance value α1 and an upper limit tolerance value α2. If a malfunction of the flowmeter 37 occurs, the dispenser 30 outputs an alarm, such as by lighting the alarm lamp 34. While significant deviations in the filling amount error ΔM are unlikely to occur during a short period such as the filling period, the control circuit 100 can detect sudden, large changes (shifts) in the filling amount error ΔM.

[0093] As a filling stop process step (S128), hydrogen filling is stopped when the pressure of the fuel tank 202 reaches the target pressure Pg, and the filling process 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 deems that the pressure of the fuel tank 202 has reached the target pressure Pg and closes the shutoff valves 36 and 38 in the dispenser 30. Furthermore, the valve control unit 65 outputs control signals to the valves 22, 24, and 26 via the communication control circuit 50, thereby controlling each valve to close.

[0094] Next, in a recording / calculation step ( S130 ), the recording / calculation unit 92 calculates the final measured filling amount Mmf and the final calculated filling amount Mcf at the end of filling, measured using the flowmeter 37, and stores these as performance data in the storage device 88, in association with the filling date and time data. The final measured filling amount Mmf is the measured filling amount Mm at the end of filling, and is the mass flow rate accumulated 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, calculated by subtracting the first weight N1 from the second weight N2 at the end of filling. Furthermore, the recording / calculation unit 92 calculates the final filling amount error ΔMf (= Mmf - Mcf) at the end of filling, and similarly stores these as performance data in the storage device 88, in association with the filling date and time data.

[0095] Thus, by repeatedly filling an unspecified large number of FCVs 200 with hydrogen, a plurality of performance data are accumulated in storage device 88. As a result, storage device 88 stores a plurality of past performance data corresponding to the final measured filling amount Mmf, the final calculated filling amount Mcf, and the final filling amount error ΔMf. Here, the final filling amount error ΔMf is stored as a plurality of error values.

[0096] In the average error calculation step ( S132 ), the average error calculation unit 93 reads the final filling amount error ΔMf of each past hydrogen filling stored in the storage device 88 , and calculates the average filling amount error ΔMave=ΣΔMf / number of fillings.

[0097] In the difference calculation step ( S134 ), the error difference calculation unit 94 calculates the error difference Mx, which is the difference between the statistical value of the multiple error values ​​based on the multiple past performance data and the error value of the current hydrogen filling. Specifically, the error difference calculation unit 94 calculates the error difference Mx by subtracting the final filling amount error ΔMf from the average filling amount error ΔMave.

[0098] As a determination step ( S136 ), the determination unit 95 compares the statistical value of a plurality of error values ​​based on a plurality of past performance data stored in the storage device 88 with the error value at the end of this hydrogen filling, determines whether the flow meter 37 has a fault, and outputs the result.

[0099] In this embodiment, the presence or absence of a fault in the flowmeter 37 is determined based on whether the error difference Mx is within the allowable range. Specifically, the determination unit 95 determines whether the error difference Mx is within the range of a lower allowable limit value β1 or greater and an upper allowable limit value β2 or less. If the error difference Mx is not within the range of a lower allowable limit value β1 or greater and an upper allowable limit value β2 or less (S136: No), the process proceeds to the alarm output step (S138). If the error difference Mx is within the range of a lower allowable limit value β1 or greater and an upper allowable limit value β2 or less (S136: Yes), the process terminates.

[0100] In the alarm output step (S138), if the flow meter 37 is determined to be faulty, the output unit 74 outputs an alarm indicating the failure of the flow meter 37 to the dispenser 30 during hydrogen filling. 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.

[0101] 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 the present invention is not limited thereto and may be a median value instead of the average value.

[0102] The lower allowable limits α1 and β1, and the upper allowable limits α2 and β2, can be set appropriately. The calculated filling amount obtained using the PVT method exhibits the aforementioned deviation due to expansion of the fuel tank 202. Therefore, the difference between the measured filling amount and the calculated filling amount obtained using the PVT method is typically not zero, but rather contains a predetermined offset. The lower allowable limits α1 and β1, and the upper allowable limits α2 and β2, can be set appropriately with this in mind.

[0103] In addition, you can also Figure 5 As shown in FIG, instead of the above-mentioned 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) are implemented as a modified example. Figure 6 As shown, instead of the above-mentioned 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) are implemented as a modified example.

[0104] In a determination step ( S119 ), the determination unit 90 determines whether the filling amount error ΔM at the current time point is greater than or equal to the lower limit permissible value α1. If the filling amount error ΔM is greater than or equal to the lower limit permissible value α1 ( S119 : “Yes”), the process proceeds to a determination step ( S122 ). If the filling amount error ΔM is not greater than or equal to the lower limit permissible value α1 ( S119 : “No”), the process proceeds to an alarm output step ( S121 ).

[0105] As an alarm output step (S121), when the filling amount error ΔM is not equal to or greater than the lower limit allowable value α1, the output unit 74 outputs an alarm 1 indicating a malfunction of the flow meter 37 to the dispenser 30 during the hydrogen filling. As an example of an alarm, the alarm lamp 34 indicating a malfunction of the flow meter 37 is illuminated in the dispenser 30.

[0106] In a determination step ( S122 ), the determination unit 90 determines whether the filling amount error ΔM is less than or equal to the upper limit permissible value α2. If the filling amount error ΔM is less than or equal to the upper limit permissible value α2 ( S122 : “Yes”), the process proceeds to a determination step ( S126 ). If the filling amount error ΔM is not less than or equal to the upper limit permissible value α2 ( S122 : “No”), the process proceeds to an alarm output step ( S123 ).

[0107] As an alarm output step (S123), if the filling amount error ΔM is not less than the upper limit allowable value α2, the output unit 74 outputs an alarm 2 indicating a failure of the flow meter 37 to the dispenser 30 during the hydrogen filling. As an example of an alarm, the alarm lamp 35 indicating a failure of the flow meter 37 is illuminated in the dispenser 30.

[0108] As described above, in the determination process during filling, if the filling amount error ΔM is not less than the upper allowable limit α2, the cause can be either a failure 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 greater than the lower allowable limit α1, it can be determined that the flow meter 37 is faulty. Therefore, by dividing the determination process by upper and lower limits and separating the alarm contents, the fault location can be easily identified.

[0109] Likewise, Figure 6 As shown, as a determination step (S140), the determination unit 95 determines whether the calculated error difference value Mx is greater than or equal to the lower limit allowable value β1. If the error difference value Mx is greater than or equal to the lower limit allowable value β1 (S140: "Yes"), the process proceeds to a determination step (S142). If the error difference value Mx is not greater than or equal to the lower limit allowable value β1 (S140: "No"), the process proceeds to an alarm output step (S141).

[0110] As an alarm output step (S141), when the error difference Mx is not equal to or greater than the lower limit allowable value β1, the output unit 74 outputs an alarm 1 indicating a malfunction of the flow meter 37 to the dispenser 30 during hydrogen filling. As an example of an alarm, the alarm lamp 34 indicating a malfunction of the flow meter 37 is illuminated in the dispenser 30.

[0111] In a determination step ( S142 ), the determination unit 95 determines whether the calculated error difference value Mx is equal to or less than the upper limit permissible value β2. If the error difference value Mx is equal to or less than the upper limit permissible value β2 ( S142 : Yes), the process ends. If the error difference value Mx is not equal to or less than the upper limit permissible value β2 ( S142 : No), the process proceeds to an alarm output step ( S143 ).

[0112] As an alarm output step (S143), when the error difference Mx is not less than the upper limit allowable value β2, the output unit 74 outputs an alarm 2 indicating a failure of the flow meter 37 to the dispenser 30 during the hydrogen filling. As an example of an alarm, the alarm lamp 35 indicating a failure of the flow meter 37 is illuminated in the dispenser 30.

[0113] As described above, in the determination process at the end of filling, if the error difference Mx is not less than the upper limit permissible value β2, the cause can be either or both of a failure in the flow meter 37 and a leak in the piping from the flow meter 37 to the fuel tank 202. On the other hand, if the error difference Mx is not greater than the lower limit permissible value β1, it can be determined that the failure is in the flow meter 37. Therefore, by dividing the determination process by upper and lower limits and separating the alarm contents, the failure location can be easily identified.

[0114] In addition, through the above-mentioned filling action, the filling amount of hydrogen gas in each accumulator 10, 12, and 14 decreases. Therefore, next, the pressure recovery mechanism 104 restores the pressure of each accumulator 10, 12, and 14. The pressure recovery mechanism 104 is composed of a compressor 40 and valves 21, 23, and 25. First, the system control unit 58 selects a hydrogen supply source connected to the suction side of the compressor 40 from a container, an intermediate accumulator, a hydrogen trailer, or a hydrogen manufacturing device (none of which are shown in the figure). Then, the pressure recovery control unit 61 controls the pressure recovery mechanism 104 under the control of the system control unit 58 to restore the pressure of each accumulator 10, 12, and 14.

[0115] Specifically, the operation proceeds as follows. The pressure accumulators used to fill fuel tank 202 can also recover pressure during filling. However, this requires insufficient time to recover to the required pressure, so pressure recovery is necessary even after filling. Switching is performed in the order of the first, second, and third accumulators. Therefore, pressure in accumulator 10, the first accumulator, is restored first. Valve control unit 60 opens valve 21 from the closed state of valves 21, 23, and 25.

[0116] Then, the compressor control unit 62 drives the compressor 40 to compress and deliver low-pressure (e.g., 0.6 MPa) hydrogen from the hydrogen supply source to fill the accumulator 10 with hydrogen until the pressure reaches a specified pressure P0 (e.g., 82 MPa), thereby restoring the pressure of the accumulator 10.

[0117] Next, the valve control unit 60 closes valve 21 and opens valve 23 instead. The compressor control unit 62 then drives the compressor 40 to compress and deliver low-pressure (e.g., 0.6 MPa) hydrogen gas, thereby filling the accumulator 12 with hydrogen gas until the pressure reaches a predetermined pressure P0 (e.g., 82 MPa), thereby restoring the pressure in the accumulator 12.

[0118] Next, the valve control unit 60 closes valve 23 and opens valve 25 instead. The compressor control unit 62 then drives the compressor 40 to compress and deliver low-pressure (e.g., 0.6 MPa) hydrogen gas, thereby filling the accumulator 14 with hydrogen gas until the pressure reaches a predetermined pressure P0 (e.g., 82 MPa), thereby restoring the pressure in the accumulator 14.

[0119] Through the above, the next FCV 200 that arrives at the hydrogen refueling station 102 can also be supplied with hydrogen.

[0120] 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 a filling operation while using a malfunctioning flow meter 37.

[0121] Next, another example of calculating the calculated filling amount Mc in the aforementioned filling amount error calculation step (S116) will be described. In the aforementioned filling amount error calculation step (S116), the capacity V of the fuel tank 202 used to calculate the calculated filling amount Mc is a predetermined value inherent to the FCV 200, and the expansion coefficient of the fuel tank 202 is not specifically considered. Therefore, the calculated filling amount obtained using the PVT method exhibits deviations due to the aforementioned expansion of the fuel tank 202. Consequently, the difference between the measured filling amount and the calculated filling amount obtained using the PVT method is generally not zero, but rather contains a predetermined offset.

[0122] The inventors of this application conducted extensive research and discovered that the deviation caused by the expansion of fuel tank 202 is not always constant. Instead, the amount of deviation varies 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 acquired during multiple hydrogen filling operations at hydrogen refueling station 102.

[0123] [Table 1]

[0124]

[0125] The filling data includes the measured filling volume 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 obtained at the completion of filling. Furthermore, the control circuit 100 calculates the calculated filling volume Mc and subtracts the calculated filling volume Mc from the measured filling volume Mm to calculate the filling volume error ΔM. The percentage error shown in Table 1 is 100 × (filling volume error ΔM / measured filling volume Mm).

[0126] Figure 8 This is a graph showing the relationship between the pressure difference during filling and the filling amount error for each filling data in Table 1. Figure 8 The horizontal axis of the graph shown is the pressure difference during 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. As the standard pressure Ps, the average value of the second pressure P2 at the end of filling included in a plurality of filling data acquired in the past can be used. Alternatively, the filling amount error relative to the pressure difference during filling, calculated by assuming the average value of the second pressure P2 at the end of filling as the standard pressure Ps, can be used. Figure 8 Plot as shown, and then make the coefficient of determination R of the approximate formula y 2 The standard pressure Ps is corrected to be close to 1. Standard pressure Ps can be corrected using known fitting methods. Standard pressure Ps may also fluctuate depending on the outside air temperature. Therefore, it can be statistically calculated for seasonal variations in outside air temperature. In one example fuel tank, the specific value of standard pressure Ps is 78 [MPa]. Figure 8 The vertical axis of the graph shown represents the filling amount error ΔM [kg].

[0127] like Figure 8 As shown, the greater the pressure difference during filling, the greater the filling amount error ΔM. This yields the relationship shown in Equation y, indicating a high correlation between the pressure difference during filling and the filling amount error. Furthermore, Equation y and the standard pressure Ps are values ​​appropriate for a particular fuel tank. By statistically calculating Equation y for each fuel tank type or vehicle model, it is possible to accommodate a wide variety of FCVs 200 arriving at the hydrogen refueling station 102.

[0128] Therefore, based on Figure 8 The results shown in the figure show that the calculated filling volume Mc is calculated using a value that takes into account the tank's expansion coefficient as the tank capacity used in the PVT method. Specifically, when the tank's inherent standard capacity is set to Vs and the expansion coefficient is set to Ex, the first function representing the first capacity V1 of the fuel tank 202 in the filling volume calculation before filling begins is V1 = Vs + (Vs × Ex) × (P1 / Ps) 3 In the first function, the correction amount of the tank capacity corresponding to the expansion rate Ex is proportional to the cube of the first pressure P1. In addition, the second function representing the second capacity V2 of the fuel tank 202 in the filling amount calculation after the start of filling is V2 = Vs + (Vs × Ex) × (P2 / Ps) 3 In the second function, the correction amount of the tank capacity corresponding to the expansion rate Ex is proportional to the cube of the second pressure P2. In addition, the expansion rate Ex and the standard capacity Vs are, for example, as described above. Figure 8 The results shown are for reference only and are set according to the type of fuel tank 202 and are stored in advance in the storage device 80. Alternatively, instead of setting the first and second functions as mathematical expressions, they may be stored in advance in the storage device 80 as a table corresponding to parameters such as the first pressure P1 and the second pressure P2 of the fuel tank. Alternatively, the second function may be V2 = Vs + (Vs × Ex) × (P2 / Ps). 1 In other words, in the second function, the correction amount of the tank capacity corresponding to the expansion rate Ex may be proportional to the second pressure P2.

[0129] Next, a flow meter failure determination method using the first volume V1 and the second volume V2 taking into account the expansion rate of the fuel tank 202 will be described. The outline of the hydrogen filling method including the determination method is the same as that described above. Figure 5 、 Figure 6 The flowcharts shown are substantially the same, but differ in that the first volume V1 and the second volume V2 taking the expansion rate of the fuel tank 202 into consideration are used in calculating the filling amount Mc used in the filling amount error calculation step ( S116 ).

[0130] Specifically, the flow meter failure determination method involved in this embodiment includes the following steps: using the flow meter 37 to measure the filling amount of hydrogen gas filled into the fuel tank 202 (measured filling amount Mm) (S114); obtaining information on the pressure P and temperature T of the fuel tank 202 (S102); calculating the filling amount of hydrogen gas filled into the fuel tank 202 (calculated filling amount Mc) based on the obtained pressure P and temperature T and the capacity V of the fuel tank 202 taking into account the expansion coefficient Ex of the fuel tank 202 (S112); and using the error value (filling amount error ΔM) between the measured filling amount (metered filling amount Mm) and the calculated filling amount (calculated filling amount Mc) to determine whether the flow meter 37 has a failure (S118).

[0131] As a result, in the filling amount calculation step ( S112 ), the tank expansion coefficient Ex is taken into account when calculating the calculated filling amount Mc based on information about the pressure P, temperature T, and volume V of the fuel tank 202. This improves 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 reduced, and the deviation is reduced, thereby improving the accuracy of fault detection in the flowmeter 37. The filling amount error ΔM can also be calculated at any time after the start of filling. Alternatively, the filling amount error ΔM can be calculated at the end of filling, and the validity of the filling amount error ΔM can 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 filling amount was accurately measured for each filling. Alternatively, the filling amount error ΔM can be calculated midway before the end of filling, and the validity of the filling amount error ΔM during the mid-filling process can be evaluated. By evaluating the validity of the filling amount error ΔM during the mid-filling process, it is possible to detect faults that may occur during the mid-filling process at an early stage.

[0132] The flow meter failure determination method according to this embodiment includes an alarm output step (S120, S121, S123) for outputting the result of the determination. In the above example, the alarm light is illuminated, but the type of alarm is not limited to this. In the alarm output step, a signal for activating a notification unit (display panel, sound output, alarm light, etc.) of the distributor 30 equipped with the flow meter 37 may also be output. In the alarm output step, a signal for notifying a monitor or monitoring device at a remote location via a network may also be output.

[0133] Using the 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 filling begins, and the 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 filling begins, the calculated filling amount Mc is calculated as Mc = N2 - N1 ( S112 ). As described above, the first and second functions represented by the mathematical expressions stored in the storage device 80 can be used to calculate the first and second volumes V1 and V2 of the fuel tank 202. This allows for simple calculations based on information from the pressure gauge 206 and the temperature gauge 207 of the fuel tank 202.

[0134] Here, the first function and the second function differ. Under conditions where the pressure inside the fuel tank 202 is relatively low before filling begins, the first function can be used to accurately calculate the capacity, taking into account the expansion coefficient of the fuel tank 202. On the other hand, under conditions where the pressure inside the fuel tank 202 is relatively high after filling begins, the second function can be used to accurately calculate the capacity, taking into account the expansion coefficient of the fuel tank 202. Specifically, the first function corrects the tank capacity for the expansion coefficient based on the first pressure P1, while the second function corrects the tank capacity for the expansion coefficient based on the second pressure P2. This allows for more accurate calculation of the capacity of the fuel tank 202 than when the correction amount for the expansion coefficient is assumed to be constant regardless of the tank pressure. Furthermore, by substituting the correction function, which takes into account the expansion coefficient, into the calculation formula for calculating the filling quantity Mc, the filling quantity error ΔM can be more appropriately calculated for each filling, allowing for quick and simple fault diagnosis of the flowmeter 37. In other words, even without accumulating the large amount of past performance data required to calculate the average filling quantity error ΔMave, fault diagnosis of the flowmeter 37 can be performed with high accuracy.

[0135] For the first pressure P1, a nonlinear first function (V1 = V + (V × Ex) × (P1 / Ps) 3) to calculate the first capacity V1 before filling begins. The inventors of this application focused on the fact that when the fuel tank 202 is filled with a large amount (when the difference between the first pressure P1 and the second pressure P2 is large), the deviation between the measured filling amount Mm and the calculated filling amount Mc (i.e., the filling amount error ΔM) is large. The first pressure P1 of the fuel tank 202 depends on the amount of hydrogen consumed according to the distance traveled by the FCV 200 to the hydrogen filling station 102, and therefore varies greatly depending on the situation. On the other hand, the second pressure P2 of the fuel tank 202 varies less depending on the situation. Therefore, a situation in which the fuel tank 202 is filled with a large amount can be considered a situation in which the first pressure P1 of the fuel tank 202 is low. By using a nonlinear function for the acquired information on the internal tank pressure (first pressure P1) as the first function that takes into account the first pressure P1, the capacity of the fuel tank 202 can be calculated with higher accuracy, compared to a situation in which the expansion coefficient is assumed to increase proportionally with the internal tank pressure. This is particularly effective when the first pressure P1 is low and the filling amount is large.

[0136] On the other hand, the second function considering the second pressure P2 can use either a nonlinear function or a linear function for the acquired tank internal pressure (second pressure P2). Compared to the first pressure P1, the second pressure P2 at the end of filling has less variation depending on the conditions. Therefore, whether the value of (P2 / Ps) is corrected by a cubic method or a linear method, the filling amount error ΔM2 can be calculated with high accuracy. However, an evaluation using actual data shows that the linear correction of the second function considering the second pressure P2 at the end of filling is more preferable. Furthermore, the second pressure P2 at mid-filling has greater variation depending on the conditions than at the end of filling. Therefore, when calculating the second weight N2 mid-filling, it may be desirable to use a nonlinear function that corrects the value of (P2 / Ps) by a cubic method.

[0137] The control circuit 100 (specifically, the receiving unit 52) ​​may also obtain information regarding the type of fuel tank 202 from the FCV 200. The control circuit 100 may also obtain information regarding the vehicle type from the FCV 200 to determine the type of fuel tank 202 corresponding to the vehicle type. A table correlating vehicle types with fuel tank types may also be pre-stored in the storage device 80. The first and second functions associated with the first capacity V1 or the second capacity V2 may also be set based on the type of fuel tank 202. This allows for fault determination of the flow meter 37 when filling fuel tanks of various vehicle types with hydrogen.

[0138] As described above, the failure determination method according to this embodiment can verify the accuracy of the dispenser 30, more specifically the flow meter 37, in the hydrogen refueling station 102. Furthermore, the accuracy of the flow meter 37 can be continuously verified each time the FCV 200 is filled with hydrogen without shutting down the hydrogen refueling station 102.

[0139] In addition, the hydrogen filling device 500 involved in this embodiment includes: a metering machine (dispenser 30) which uses a flow meter 37 to measure the filling amount (measured filling amount Mm) of hydrogen gas filled into the fuel tank 202 of the vehicle; an acquisition unit (receiving unit 52) ​​which acquires information on the pressure P and temperature T of the fuel tank 202; a filling amount calculation unit 87 which calculates the filling amount (calculated filling amount Mc) of hydrogen gas filled into the fuel tank 202 from the metering machine (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 coefficient Ex of the fuel tank 202; and a determination unit 90 which uses an error value (filling amount error ΔM) between the filling amount measured by the flow meter 37 (measured filling amount Mm) and the calculated filling amount (calculated filling amount Mc) to determine whether the flow meter 37 has a malfunction.

[0140] While the present invention has been described above with reference to the aforementioned embodiments, the present invention is not limited to the aforementioned embodiments. Appropriate combinations and substitutions of the structures of the embodiments are also encompassed within the present invention. Furthermore, based on the knowledge of those skilled in the art, it is possible to appropriately reorganize the combinations and processing sequences in the embodiments, or to modify the embodiments by various design changes. Such modified embodiments are also encompassed within the scope of the present invention.

[0141] Industrial applicability

[0142] The present invention relates to a technique for determining a failure of a measuring device included in a hydrogen filling device.

[0143] Description of Reference Numerals

[0144] 10, 12, 14: Accumulator; 30: Dispenser; 34, 35: Alarm lights; 37: Flow meter; 39: Display panel; 40: Compressor; 43: Control circuit; 50: Communication control circuit; 51: Memory; 52: Receiver; 54: Target pressure / temperature calculation unit; 58: System control unit; 64: Dispenser control unit; 67: Dispenser information receiver; 74: Output unit; 76: Monitor; 80: Storage device; 84: Storage device; 85: Gas Weight calculation unit; 86: Determination unit; 87: Filling quantity calculation unit; 88: Storage device; 89: Filling quantity error calculation unit; 90, 91: Determination unit; 92: Recording / calculation unit; 94: Error difference calculation unit; 95: Determination unit; 96: Setting unit; 100: Control circuit; 101: Multi-stage accumulator; 102: Hydrogen filling station; 200: FCV; 202: Fuel tank; 204: On-board unit; 206: Pressure gauge; 207: Thermometer; 500: Hydrogen filling system.

Claims

1. A hydrogen filling device, characterized in that: have: a metering machine that uses a flow meter to measure the amount of hydrogen gas filled into the fuel tank; an acquiring unit configured to acquire information on the pressure and temperature of the fuel tank; a filling amount calculation unit that calculates a corrected capacity 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, and calculates a filling amount of hydrogen gas filled into the fuel tank from the metering device based on the acquired pressure and temperature and the corrected capacity of the fuel tank; as well as A determination unit determines whether the flow meter has a malfunction using an error value between the filling amount measured by the flow meter and the calculated filling amount.

2. The hydrogen filling device according to claim 1, characterized in that The filling amount calculation unit calculates a first weight of hydrogen gas in the fuel tank before filling is started based on a first pressure, a first temperature, and a first capacity of the fuel tank before filling is started. The filling amount calculation unit calculates 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 capacity of the fuel tank after the start of filling. The first capacity is calculated using the expansion ratio and a first pressure ratio of the first pressure to the standard pressure, The second capacity is calculated using the expansion rate and a second pressure ratio of the second pressure to the standard pressure, The calculated filling amount is calculated using the first weight and the second weight.

3. The hydrogen filling device according to claim 2, characterized in that The first capacity is calculated using a nonlinear first function for the first pressure ratio, The second capacity is calculated using a second function that is linear or nonlinear for the second pressure ratio.

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

5. The hydrogen filling device according to claim 3 or 4, characterized in that The acquiring unit further acquires information related to the type of the fuel tank. The first function and the second function are set according to the type of the fuel tank.

6. A flow meter fault determination method, characterized in that: The process includes the following steps: A flow meter is used to measure the amount of hydrogen gas filled into the fuel tank; obtaining information on the pressure and temperature of the fuel tank; calculating a corrected capacity 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 filled in the fuel tank based on the acquired pressure and temperature and the corrected capacity of the fuel tank; as well as The presence or absence of a malfunction in the flow meter is determined using an error value between the measured filling amount and the calculated filling amount.

Images