Patent Description:
Conventionally, a flowmeter failure diagnosis method of a measurer has been devised, the method including a step of determining the presence or absence of a failure of a flowmeter using a plurality of error values based on a plurality of pieces of past result data stored in a storage device between a measured filling amount at the end of filling measured using the flowmeter and a calculated filling amount at the end of filling calculated using a pressure, a temperature, and a capacity of a tank, and an error value at the end of current hydrogen gas filling, and outputting a result (see Patent Literature <NUM>).

Incidentally, a difference between the measured filling amount and the calculated filling amount does not generally become zero due to expansion of the fuel tank, and there is an offset amount. For this reason, in the failure diagnosis method described above, when a failure is determined using a difference value between the measured filling amount and the calculated filling amount as an error value, an allowable value is set in consideration of a predetermined offset amount. However, as a result of further studies by the inventors of the present application, it has been found that an expansion rate of the fuel tank is not necessarily constant and depends on a filling pressure.

The present invention has been made in view of such a situation, and an exemplary object thereof is to provide new technology for improving the accuracy of flowmeter failure determination.

A flowmeter failure determination method according to one aspect of the present invention includes: a step of measuring a filling amount of hydrogen gas filled in a fuel tank of an automobile, using a flowmeter; a step of acquiring information of a pressure and a temperature of the fuel tank; a step of calculating the filling amount of the hydrogen gas filled in the fuel tank based on the acquired pressure and temperature and a capacity of the fuel tank in which an expansion rate of the fuel tank is considered; and a step of determining presence or absence of a failure of the flowmeter using an error value between the measured filling amount and the calculated filling amount.

According to one aspect of the present invention, it is possible to improve the accuracy of flowmeter failure determination.

First, aspects of the present invention will be listed. A flowmeter failure determination method according to one aspect of the present invention includes: a step of measuring a filling amount of hydrogen gas filled in a fuel tank of an automobile, using a flowmeter; a step of acquiring information of a pressure and a temperature of the fuel tank; a step of calculating the filling amount of the hydrogen gas filled in the fuel tank based on the acquired pressure and temperature and a capacity of the fuel tank in which an expansion rate of the fuel tank is considered; and a step of determining presence or absence of a failure of the flowmeter using an error value between the measured filling amount and the calculated filling amount.

According to this aspect, since the expansion rate of the fuel tank is considered at the time of calculating the filling amount, the calculation accuracy of the filling amount is improved. In other words, since the error value between the measured filling amount and the calculated filling amount is reduced and the variation is reduced, the accuracy of failure determination of the flowmeter is improved.

A step of outputting a determined result may be further included. By outputting the determination result of the presence or absence of the failure of the flowmeter, the presence or absence of the failure of the flowmeter can be quickly grasped.

A step of calculating a first weight of the hydrogen gas in the fuel tank before a start of filling based on a first pressure, a first temperature, and a first capacity of the fuel tank before the start of filling, and a step of calculating a second weight of the 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 may be further included. The calculated filling amount may be calculated using the first weight and the second weight. By using the first capacity before the start of filling and the second capacity after the start of filling, the calculation accuracy of the filling amount can be improved.

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 accurately calculated. In particular, it is possible to accurately calculate the first capacity in consideration of the expansion rate in a situation where the pressure in the fuel tank before the start of filling becomes relatively low. By calculating the second capacity using the second pressure, the second weight after the start of filling can be accurately calculated. In particular, it is possible to accurately calculate the second capacity in consideration of the expansion rate in a situation where the pressure in the fuel tank after the start of filling becomes relatively high. As a result, the calculation accuracy of the filling amount can be improved as compared with a case where the capacity is constant regardless of the pressure in the fuel tank.

The first capacity may be calculated using a first function that is non-linear with respect to the first pressure, and the second capacity may be calculated using a second function that is linear or non-linear with respect to the second pressure. The first function and the second function are expressed by, for example, mathematical expressions stored in a storage device. The inventors of the present application have focused on the fact that a deviation between the measured filling amount and the calculated filling amount increases in a situation where the filling amount is large (a situation where a difference between the first pressure and the second pressure is large). In particular, when the first pressure is small, the filling amount may be large. By calculating the first capacity using the first function that is non-linear with respect to the first pressure, the calculation accuracy of the first capacity can be improved as compared with a case of calculating the first capacity using a function proportional to the pressure in the fuel tank.

A step of specifying a type of the fuel tank may be further included. The first function and the second function may be set according to the type of the fuel tank. As a result, it is possible to determine the failure of the flowmeter when fuel tanks of various vehicle types are filled with the hydrogen gas.

Another aspect of the present invention is a hydrogen filling apparatus. This apparatus includes: a measurer that measures a filling amount of hydrogen gas filled in a fuel tank of an automobile, using a flowmeter; an acquirer that acquires information of a pressure and a temperature of the fuel tank; a filling amount calculator that calculates the filling amount of the hydrogen gas filled in the fuel tank from the measurer based on the acquired pressure and temperature and a capacity of the fuel tank in which an expansion rate of the fuel tank is considered; and a determiner that determines the presence or absence of a failure of the flowmeter using an error value between the filling amount measured using the flowmeter and the calculated filling amount.

addition, appropriate combinations of the above-described elements can also be included in the scope of the invention for which patent protection is sought by the present patent application.

Hereinafter, the present invention will be described based on preferred embodiments while referring to the drawings. The embodiments do not limit the invention, but are exemplary, and all features and combinations thereof described in the embodiments are not necessarily essential to the invention. The same or equivalent components, members, and processes illustrated in the drawings will be denoted by the same reference numerals, and repeated description will be omitted as appropriate. In addition, the scale and shape of each part illustrated in the drawings are set conveniently in order to facilitate the description, and are not limitedly interpreted unless otherwise specified. In addition, even in a case of the same member, scales and the like may be slightly different between the drawings. In addition, when the terms "first", "second", and the like are used in the present specification or claims, such terms do not represent any order or degree of importance and are used to distinguish one configuration from another configuration, unless otherwise specified.

First, an example of a hydrogen filling system to which the present invention can be applied will be described. <FIG> is a diagram illustrating an example of a configuration of a hydrogen filling system of a hydrogen station according to the present embodiment. In <FIG>, a hydrogen filling system <NUM> is disposed in a hydrogen station <NUM>. The hydrogen filling system (hydrogen filling apparatus) <NUM> includes a multi-stage accumulator <NUM>, a dispenser (measurer) <NUM>, a compressor <NUM>, and a control circuit <NUM>. The multi-stage accumulator <NUM> includes a plurality of accumulators <NUM>, <NUM>, and <NUM> having different use lower limit pressures.

In the example of <FIG>, the multi-stage accumulator <NUM> is configured by the three accumulators <NUM>, <NUM>, and <NUM>. For example, the accumulator <NUM> functions as a 1st bank having a low use lower limit pressure, the accumulator <NUM> functions as a 2nd bank having an intermediate use lower limit pressure, and the accumulator <NUM> functions as a 3rd bank having a high use lower limit pressure. However, the present invention is not limited thereto. The accumulators used as the 1st bank to the 3rd bank can be replaced as necessary. In the hydrogen station <NUM>, a cylinder, an intermediate accumulator, or a hydrogen production apparatus (none of which are illustrated in the drawings) is also disposed. A hydrogen trailer (not illustrated in the drawings) that delivers filled hydrogen gas arrives at the hydrogen station <NUM>.

In <FIG>, the suction side of the compressor <NUM> is connected to the cylinder, the intermediate accumulator, the filling tank of the hydrogen trailer, or the hydrogen production apparatus described above by a pipe.

The discharge side of the compressor <NUM> is connected to the accumulator <NUM> via a valve <NUM> by a pipe. Similarly, the discharge side of the compressor <NUM> is connected to the accumulator <NUM> via a valve <NUM> by a pipe. Similarly, the discharge side of the compressor <NUM> is connected to the accumulator <NUM> via a valve <NUM> by a pipe.

The accumulator <NUM> is connected to the dispenser <NUM> via a valve <NUM> by a pipe. The accumulator <NUM> is connected to the dispenser <NUM> via a valve <NUM> by a pipe. The accumulator <NUM> is connected to the dispenser <NUM> via a valve <NUM> by a pipe. As such, the dispenser <NUM> is commonly connected to the accumulators <NUM>, <NUM>, and <NUM> configuring the multi-stage accumulator <NUM>.

In <FIG>, a shut-off valve <NUM>, a flow rate adjustment valve <NUM>, a flowmeter <NUM>, a cooler <NUM> (precooler), a shut-off valve <NUM>, an emergency detachment coupler <NUM>, and a control circuit <NUM> are disposed in the dispenser <NUM>. A nozzle <NUM> extending to the outside of the dispenser <NUM> is disposed in the dispenser <NUM>. The dispenser <NUM> sends hydrogen gas (hydrogen fuel) supplied from the multi-stage accumulator <NUM> to the cooler <NUM> via the shut-off valve <NUM>, the flow rate adjustment valve <NUM>, and the flowmeter <NUM>. At that time, a flow rate of the hydrogen gas supplied from the multi-stage accumulator <NUM> per unit time is controlled by the flow rate adjustment valve <NUM>.

The dispenser <NUM> measures a filling amount of hydrogen gas to be filled in a fuel tank <NUM> of a fuel cell vehicle (FCV) <NUM> from the multi-stage accumulator <NUM>. Specifically, a mass flow rate of the hydrogen gas to be filled in the fuel tank <NUM> is measured by the flowmeter <NUM>. In the present embodiment, for example, a Coriolis-type mass flowmeter is used as the flowmeter <NUM>. The control circuit <NUM> integrates the mass flow rate measured by the flowmeter <NUM> to measure the filling amount. The filling amount measured using the flowmeter <NUM> is also referred to as a "measured filling amount". The filled hydrogen gas is cooled to, for example, -<NUM> by the cooler <NUM>. The cooled hydrogen gas is filled in the fuel tank <NUM> through the shut-off valve <NUM>, the emergency detachment coupler <NUM>, and the nozzle <NUM> using a differential pressure.

The control circuit <NUM> is configured to be able to communicate with an on-vehicle device <NUM> in the FCV <NUM>. For example, the control circuit <NUM> can wirelessly communicate with the on-vehicle device <NUM> using infrared rays. The control circuit <NUM> is connected to the control circuit <NUM> that controls the entire hydrogen filling system <NUM>. A display panel <NUM> is disposed on an outer surface of the dispenser <NUM>. Alarm lamps <NUM> and <NUM> are disposed inside the display panel <NUM>.

In the hydrogen filling system <NUM> in <FIG>, a plurality of pressure gauges are disposed at different positions in a flow passage of the hydrogen fuel between the multi-stage accumulator <NUM> and the outlet of the dispenser <NUM>. Specifically, a pressure in the accumulator <NUM> is measured by a pressure gauge <NUM>. A pressure in the accumulator <NUM> is measured by a pressure gauge <NUM>. A pressure in the accumulator <NUM> is measured by a pressure gauge <NUM>. A pressure in the vicinity of the inlet in the dispenser <NUM> is measured by a pressure gauge <NUM>. A pressure in the vicinity of the outlet in the dispenser <NUM> is measured by a pressure gauge <NUM>.

In the example of <FIG>, the pressure gauge <NUM> measures the pressure of the upstream side (primary side) of the shut-off valve <NUM> located at the primary side of the cooler <NUM>. The pressure gauge <NUM> measures the pressure in the vicinity of the emergency detachment coupler <NUM> on the secondary side of the cooler <NUM>. Pressure data measured by each pressure gauge is output to the control circuit <NUM> at all times or at a predetermined sampling cycle (for example, <NUM> msec to several sec. In other words, the control circuit <NUM> monitors the pressure measured by each pressure gauge at all times or at a predetermined sampling cycle.

The pressure of the fuel tank <NUM> is measured by a pressure gauge <NUM> mounted on the FCV <NUM>. As will be described later, the pressure of the fuel tank <NUM> is monitored at all times or at predetermined sampling intervals (for example, <NUM> msec to several sec. ) while communication between the on-vehicle device <NUM> and the control circuit <NUM> is established.

A temperature of the hydrogen gas in the vicinity of the outlet in the dispenser <NUM> is measured by a thermometer <NUM>. The thermometer <NUM> measures a temperature in the vicinity of the emergency detachment coupler <NUM>, for example, on the secondary side of the cooler <NUM>. In addition, an outside air temperature in the vicinity of the dispenser <NUM> is measured by the thermometer <NUM>. Temperature data measured by each thermometer is output to the control circuit <NUM> at all times or at a predetermined sampling cycle (for example, <NUM> msec to several <NUM> sec. In other words, the control circuit <NUM> monitors the temperature measured by each thermometer at all times or at a predetermined sampling cycle.

A temperature of the fuel tank <NUM> is measured by a thermometer <NUM> mounted on the FCV <NUM>. As will be described later, the temperature of the fuel tank <NUM> is monitored at all times or at predetermined sampling intervals (for example, <NUM> msec to several sec. ) while communication between the on-vehicle device <NUM> and the control circuit <NUM> is established.

The hydrogen gas accumulated in the cylinder, the intermediate accumulator, or the tank of the hydrogen trailer is supplied to the suction side of the compressor <NUM> in a state where a pressure is reduced to a low pressure (for example, <NUM> MPa) by each regulator (not illustrated in the drawings) controlled by the control circuit <NUM>. Similarly, the hydrogen gas produced by the hydrogen production apparatus is supplied to the suction side of the compressor <NUM> in a state of a low pressure (for example, <NUM> MPa). The compressor <NUM> compresses the hydrogen gas supplied at a low pressure under the control of the control circuit <NUM>, and supplies the compressed hydrogen gas to each of the accumulators <NUM>, <NUM>, and <NUM> of the multi-stage accumulator <NUM>. The compressor <NUM> compresses the hydrogen gas until the pressure in each of the accumulators <NUM>, <NUM>, and <NUM> reaches a predetermined high pressure (for example, <NUM> MPa). In other words, the compressor <NUM> compresses the hydrogen gas until a secondary side pressure POUT of the discharge side becomes a predetermined high pressure (for example, <NUM> MPa).

The control circuit <NUM> determines any one of the cylinder, the intermediate accumulator, the hydrogen trailer, and the hydrogen production apparatus as a supply source for supplying the hydrogen gas to the suction side of the compressor <NUM>. Similarly, the control circuit <NUM> determines which one of the accumulators <NUM>, <NUM>, and <NUM> the hydrogen gas is supplied to from the compressor <NUM> by controlling opening and closing of the valves <NUM>, <NUM>, and <NUM>. The control circuit <NUM> may perform control to simultaneously supply the hydrogen gas from the compressor <NUM> to two or more accumulators.

In the example described above, the case where a pressure PIN at which the hydrogen gas is supplied to the suction side of the compressor <NUM> is controlled so as to be reduced to the predetermined low pressure (for example, <NUM> MPa) is illustrated. However, the present invention is not limited thereto. For example, when the hydrogen gas accumulated in the cylinder, the intermediate accumulator, or the hydrogen trailer is supplied to the suction side of the compressor <NUM>, the pressure of the hydrogen gas may not be reduced or may be reduced to a pressure higher than a predetermined low pressure (for example, <NUM> MPa).

The hydrogen gas accumulated in the multi-stage accumulator <NUM> is cooled by the cooler <NUM> in the dispenser <NUM> and supplied from the dispenser <NUM> to the FCV <NUM>.

<FIG> is a configuration diagram illustrating an example of an internal configuration of a control circuit that controls the entire hydrogen filling system according to the present embodiment. In <FIG>, a communication control circuit <NUM>, a memory <NUM>, a receiver <NUM>, a target pressure/temperature calculator <NUM>, a system controller <NUM>, a pressure recovery controller <NUM>, a supply controller <NUM>, a bank pressure receiver <NUM>, a dispenser information receiver <NUM>, an outputter <NUM>, a gas weight calculator <NUM>, a determiner <NUM>, a filling amount calculator <NUM>, a filling amount error calculator <NUM>, a determiner <NUM>, a determiner <NUM>, a recorder/calculator <NUM>, an average error calculator <NUM>, an error difference value calculator <NUM>, a determiner <NUM>, a setter <NUM>, a monitor <NUM>, and storage devices <NUM>, <NUM>, and <NUM> such as magnetic disk devices are disposed in the control circuit <NUM>. The pressure recovery controller <NUM> has a valve controller <NUM> and a compressor controller <NUM>. The supply controller <NUM> has a dispenser controller <NUM> and a valve controller <NUM>.

Each device such as the receiver <NUM>, the target pressure/temperature calculator <NUM>, the system controller <NUM>, the pressure recovery controller <NUM> (the valve controller <NUM> and the compressor controller <NUM>), the supply controller <NUM> (the dispenser controller <NUM> and the valve controller <NUM>), the bank pressure receiver <NUM>, the dispenser information receiver <NUM>, the outputter <NUM>, the gas weight calculator <NUM>, the determiner <NUM>, the filling amount calculator <NUM>, the filling amount error calculator <NUM>, the determiner <NUM>, the determiner <NUM>, the recorder/calculator <NUM>, the average error calculator <NUM>, the error difference value calculator <NUM>, the determiner <NUM>, and the setter <NUM> includes a processing circuit, and the processing circuit includes 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.

The above-described devices may use a common processing circuit (the same processing circuit). Alternatively, different processing circuits (separate processing circuits) may be used. Input data required by each of the above-described devices or a result calculated by each of the above-described devices is stored in the memory <NUM> each time.

FCV information such as a pressure P, a temperature T, and a capacity V of the fuel tank <NUM> received from the FCV <NUM> is stored in the storage device <NUM>. In the storage device <NUM>, a conversion table <NUM> indicating a correlation between a weight N of the hydrogen gas in the fuel tank <NUM> corresponding to the FCV information and filling information such as a target pressure Pg and a target temperature Tg of the hydrogen gas to be filled in the fuel tank <NUM> is stored. Further, a correction table <NUM> for correcting a result obtained from the conversion table <NUM> is stored in the storage device <NUM>.

The bank pressure receiver <NUM> receives the pressure measured by each of the pressure gauges <NUM>, <NUM>, and <NUM> in the accumulator <NUM> at all times or at a predetermined sampling cycle, and stores the pressure in the storage device <NUM> together with a reception time. The dispenser information receiver <NUM> receives the pressure measured by each of the pressure gauges <NUM> and <NUM> in the dispenser <NUM> at all times or at a predetermined sampling cycle, and stores the pressure in the storage device <NUM> together with a reception time. The dispenser information receiver <NUM> receives the temperature measured by the thermometer <NUM> in the dispenser <NUM> at all times or at a predetermined sampling cycle, and stores the temperature in the storage device <NUM> together with a reception time.

As described above, the filling amount (mass flow rate) of the hydrogen gas filled in the fuel tank <NUM> is measured using the flowmeter <NUM>. The flowmeter <NUM> measures the mass flow rate at the moment of filling, and generates a pulse for every <NUM>, for example, which is a minute flow rate unit. A pulse signal is output to the control circuit <NUM>. The control circuit <NUM> measures a measured filling amount Mm by counting the number of pulses generated from the start of filling and integrating the mass flow rate.

The measured filling amount Mm is displayed on the display panel <NUM> disposed on the outer surface of the dispenser <NUM> while a value at a present time changes every moment during filling, and is output to the control circuit <NUM>. The measured filling amount Mm is original data of a charge paid by a consumer. In other words, the charge paid by the consumer (user) is an amount of money obtained by multiplying the displayed measured filling amount Mm by a price of the hydrogen gas per unit filling amount. Therefore, the measurement accuracy of the flowmeter <NUM> becomes important.

As described above, the FCV <NUM> outputs the FCV information such as the pressure P, the temperature T, and the capacity V of the fuel tank <NUM>. The display panel <NUM> may display these numerical values. Specifically, numerical values of a pressure Pt and a temperature Tt at a current time t of the fuel tank <NUM> may be displayed on the display panel <NUM> while changing every moment.

The control circuit <NUM> calculates a density ρ(P, T) of the hydrogen gas in the fuel tank <NUM> using the pressure P and the temperature T of the fuel tank <NUM> and the compression rate unique to hydrogen. The control circuit <NUM> calculates a weight N = ρ(P, T) × V of the hydrogen gas in the fuel tank <NUM> by multiplying the density ρ(P, T) by the capacity V of the fuel tank <NUM>. The control circuit <NUM> 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 a density ρ(P1, T1) calculated from a first pressure (initial pressure) P1 and a first temperature (initial temperature) T1 of the fuel tank <NUM> before the start of filling by the capacity V (that is, N1 = ρ(P1, T1) × V). The second weight N2 is calculated by multiplying a density ρ(P2, T2) calculated from a second pressure P2 and a second temperature T2 after the start of filling by the capacity V (that is, N2 = ρ(P2, T2) × V). Here, "after the start of filling" includes timing at an arbitrary time t during filling and timing at the end of filling to end the filling.

The control circuit <NUM> calculates a filling amount Mc of the hydrogen gas 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 a "calculated filling amount". The calculated filling amount Mc is a value calculated using the pressure P and the temperature T of the fuel tank <NUM> and the compression rate unique to hydrogen, and is a value calculated by a PVT method (volume method). The calculated filling amount Mc corresponds to the weight of the hydrogen gas filled in the fuel tank <NUM> after the start of filling.

The calculated filling amount Mc can be used to evaluate the validity of the measured filling amount Mm measured using the flowmeter <NUM>. Therefore, a filling amount error ΔM obtained by subtracting the calculated filling amount Mc from the measured filling amount Mm is divided by the calculated filling amount Mc and multiplied by <NUM> to evaluate a percentage error of the flowmeter <NUM>.

<FIG> is a diagram illustrating an example of a change in percentage error of the flowmeter <NUM> with respect to the number of fillings. In the example of <FIG>, an example of a case where no abnormality has occurred in the flowmeter <NUM> during a verification period is illustrated. In <FIG>, a vertical axis represents the percentage error of the flowmeter <NUM>, and a horizontal axis represents the number of fillings. As illustrated in <FIG>, by verifying the magnitude of the time-series percentage error based on the number of fillings using many filling results, it is possible to continuously confirm a temporal change of the flowmeter <NUM>. From a result of <FIG>, it can be seen that the percentage error of the flowmeter <NUM> stably falls within a width Δ2. The reason why the percentage error of the flowmeter <NUM> is not zero and the offset Δ1 is generated on the positive side is that the fuel tank <NUM> expands due to filling, and a deviation occurs due to the expansion in the calculation result in the PVT method.

<FIG> is a diagram illustrating another example of the change in the percentage error of the flowmeter with respect to the number of fillings. In the example of <FIG>, an example of a case where an abnormality has occurred in the flowmeter <NUM> during the verification period is illustrated. In <FIG>, a vertical axis represents the percentage error of the flowmeter <NUM>, and a horizontal axis represents the number of fillings. In the example of <FIG>, it can be seen that a variation in the percentage error of the flowmeter <NUM> increases as the number of fillings increases, and a value is greatly changed (shifted) stepwise twice when the number of fillings is A and B. For a method for shifting the value, in the example of <FIG>, the positive-side offset is shifted to the negative side. As described above, a large change in the percentage error of the flowmeter <NUM> in a short period indicates that a large abnormality (failure) other than a temporal change has occurred in the flowmeter <NUM>.

First, the variation in the percentage error of the flowmeter <NUM> can be determined for the first time by continuous verification with the large number of fillings according to the present embodiment. On the other hand, in a conventional weighting method, measurement is generally performed only about four times. Therefore, in the conventional weighting method, it is difficult to determine whether or not the variation is large. For the sudden large change (shift) in the percentage error of the flowmeter <NUM>, it is possible to specify when the percentage error of the flowmeter <NUM> is greatly changed (shifted) for the first time by the continuous verification according to the present embodiment, and it is possible to detect an abnormality of the flowmeter <NUM>.

From the above results, it can be seen that it is useful to compare and verify the calculated filling amount Mc and the measured filling amount Mm. Therefore, in the present embodiment, failure diagnosis of the flowmeter <NUM> is performed using an error value between the calculated filling amount Mc and the measured filling amount Mm. In the examples of <FIG> and <FIG>, the description has been given using the percentage error, but the verifiable error value is not limited thereto. Hereinafter, a case where a filling amount error ΔM = Mm - Mc, which is a difference between the calculated filling amount Mc and the measured filling amount Mm, is used as an error value will be described.

<FIG> is a flowchart illustrating a part of steps of a hydrogen gas filling method in the present embodiment. <FIG> is a flowchart illustrating a remaining part of the step of the hydrogen gas filling method in the present embodiment.

In <FIG> and <FIG>, the hydrogen gas filling method according to the present embodiment executes a determination step (S100), an FCV information reception 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/calculation step (S130), an average error calculation step (S132), a difference calculation step (S134), a determination step (S136), and an alarm output step (S138).

When the FCV <NUM> arrives at the hydrogen station <NUM>, a worker of the hydrogen station <NUM> or a user of the FCV <NUM> connects (fits) the nozzle <NUM> of the dispenser <NUM> to a reception port (receptacle) of the fuel tank <NUM> of the FCV <NUM>, and fixes the nozzle <NUM>. Then, the worker or the user presses a filling start button (not illustrated in the drawings) in the display panel <NUM> of the dispenser <NUM>.

As the determination step (S100), the control circuit <NUM> determines whether or not the worker or the user has pressed the filling start button. When the filling start button is pressed (YES in S100), the process proceeds to the FCV information reception step (S102). When the start button is not pressed (NO in S100), the process does not proceed to the next step. When the filling start button is pressed, communication between the on-vehicle device <NUM> and the control circuit <NUM> (repeater) is established.

As the FCV information reception step (S102), the receiver <NUM> receives FCV information such as the temperature Tt, the pressure Pt, and the capacity V of the fuel tank <NUM> at the present time (time t) from the FCV <NUM>. Specifically, the following operation is performed. When communication between the on-vehicle device <NUM> and the control circuit <NUM> (repeater) is established, the FCV information (tank information) is output (transmitted) in real time from the on-vehicle device <NUM>.

The FCV information is relayed by the control circuit <NUM> included in the dispenser <NUM> and transmitted to the control circuit <NUM> that controls the entire hydrogen filling system <NUM>. In the control circuit <NUM>, the receiver <NUM> receives the FCV information via the communication control circuit <NUM>. The FCV information is monitored at all times or at predetermined sampling intervals (for example, <NUM> msec to several sec. ) while communication between the on-vehicle device <NUM> and the control circuit <NUM> is established. The received FCV information is stored in the storage device <NUM> together with information of a reception time.

As the gas weight calculation step (S104), the gas weight calculator <NUM> calculates a weight Nt of the hydrogen gas filled in the fuel tank <NUM> at the present time (time t) by using the PVT method. Specifically, the gas weight calculator <NUM> calculates a density ρ(Pt, Tt) of the hydrogen gas using the pressure Pt and the temperature Tt of the fuel tank <NUM> at the present time and the compression rate unique to hydrogen. The gas weight calculator <NUM> calculates a weight Nt = ρ(Pt, Tt) × V of the hydrogen gas in the fuel tank <NUM> at the present time by multiplying the density ρ(Pt, Tt) by the capacity V of the fuel tank <NUM>.

As the determination step (S106), the determiner <NUM> determines whether or not determination processing is first determination processing from the start of filling. When the determination processing is the first determination processing (YES in S106), the process proceeds to the initial weight setting step (S108). When the determination processing is not the first determination processing, that is, when the determination processing is second or subsequent determination processing from the start of the current filling (NO in S106), the process proceeds to the filling amount calculation step (S112) while continuing the filling step (S110) to be described later.

As the initial weight setting step (S108), the setter <NUM> sets the calculated weight Nt of the hydrogen gas to the first weight N1 when the determination processing is the first determination processing in the determination step (S106), that is, before the start of filling. The first weight N1 can be calculated as N1 = ρ(P1, T1) × V using the FCV information (the first temperature T1 and the first pressure P1) before the start of filling.

As the filling step (S110), first, the target pressure/temperature calculator <NUM> reads the conversion table <NUM> from the storage device <NUM>, and calculates the target pressure Pg and the target temperature Tg corresponding to the first pressure P1, the first temperature T1, and the capacity V of the fuel tank <NUM> and the outside air temperature T'. In addition, the target pressure/temperature calculator <NUM> reads the correction table <NUM> from the storage device <NUM> and corrects the numerical value obtained by the conversion table <NUM>. The correction table <NUM> is used to correct the numerical value obtained by the conversion table <NUM> with a correction value set based on a result obtained by an experiment, a simulation, or the like in a case where an error is large in a result obtained only by the data of the conversion table <NUM>. The calculated target pressure Pg and target temperature Tg are output to the system controller <NUM>.

Next, the fuel tank <NUM> starts to be filled with the hydrogen gas from the multi-stage accumulator <NUM> via the dispenser <NUM>.

<FIG> is a diagram illustrating a hydrogen gas filling method using the multi-stage accumulator. In <FIG>, a vertical axis represents a pressure, and a horizontal axis represents a time. In a case of performing the differential pressure filling of the hydrogen gas on the FCV <NUM>, the accumulators <NUM>, <NUM>, and <NUM> of the multi-stage accumulator <NUM> are generally accumulated at the same pressure P0 (for example, <NUM> MPa) in advance. On the other hand, the fuel tank <NUM> has the first pressure P1 at a time t0 when filling starts. A case of starting the filling of the fuel tank <NUM> with the hydrogen gas from such a state will be described.

First, filling of the fuel tank <NUM> with the hydrogen gas from the 1st bank (for example, the accumulator <NUM>) is started. Specifically, the following operation is performed. Under the control of the system controller <NUM>, the supply controller <NUM> controls a supplier <NUM> and causes the supplier <NUM> to supply the hydrogen gas from the accumulator <NUM> to the fuel tank <NUM> of the FCV <NUM>. Specifically, the system controller <NUM> controls the dispenser controller <NUM> and the valve controller <NUM>. The dispenser controller <NUM> communicates with the control circuit <NUM> of the dispenser <NUM> via the communication control circuit <NUM>, and controls the operation of the dispenser <NUM>.

Specifically, first, the control circuit <NUM> adjusts an opening of the flow rate adjustment valve in the dispenser <NUM>, and opens the shut-off valves <NUM> and <NUM> in the dispenser <NUM>. Then, the valve controller <NUM> outputs control signals to the valves <NUM>, <NUM>, and <NUM> via the communication control circuit <NUM>, and controls opening and closing of each valve. Specifically, the valve <NUM> is opened and the valves <NUM> and <NUM> are kept closed. As a result, the hydrogen gas is supplied from the accumulator <NUM> to the fuel tank <NUM>. By the differential pressure between the accumulator <NUM> and the fuel tank <NUM>, the hydrogen gas accumulated in the accumulator <NUM> moves to the side of the fuel tank <NUM> at a filling speed adjusted by the flow rate adjustment valve, and the pressure of the fuel tank <NUM> gradually increases as indicated by a dotted line Pt. Accordingly, the pressure (graph indicated by "1st") of the accumulator <NUM> gradually decreases. Then, when a time t1 at which the pressure falls below the use lower limit pressure of the 1st bank elapses, the accumulator to be used is switched from the accumulator <NUM> to the 2nd bank (for example, the accumulator <NUM>).

At the time of switching to the accumulator <NUM>, the valve controller <NUM> outputs control signals to the valves <NUM>, <NUM>, and <NUM> via the communication control circuit <NUM>, and controls opening and closing of each valve. Specifically, the valve <NUM> is opened, the valve <NUM> is closed, and the valve <NUM> is kept closed. As a result, since the differential pressure between the accumulator <NUM> and the fuel tank <NUM> increases, the filling speed can be kept high.

Then, by the differential pressure between the 2nd bank (for example, the accumulator <NUM>) and the fuel tank <NUM>, the hydrogen gas accumulated in the accumulator <NUM> moves to the side of the fuel tank <NUM>, and the pressure of the fuel tank <NUM> gradually increases as indicated by the dotted line Pt. Accordingly, the pressure (graph indicated by "2nd") of the accumulator <NUM> gradually decreases. Then, when a time t2 at which the pressure falls below the use lower limit pressure of the 2nd bank elapses, the accumulator to be used is switched from the accumulator <NUM> to the 3rd bank (for example, the accumulator <NUM>).

Then, by the differential pressure between the 3rd bank (for example, the accumulator <NUM>) and the fuel tank <NUM>, the hydrogen gas accumulated in the accumulator <NUM> moves to the side of the fuel tank <NUM>, and the pressure of the fuel tank <NUM> gradually increases as indicated by the dotted line Pt. Accordingly, the pressure (graph indicated by "3rd") of the accumulator <NUM> gradually decreases. Then, the fuel tank <NUM> is filled with the hydrogen gas by the 3rd bank until the pressure of the fuel tank reaches the target pressure Pg (for example, <NUM> to <NUM> MPa).

As described above, the fuel tank <NUM> is filled with the hydrogen gas in order from the 1st bank. Further, a filling amount of the hydrogen gas during filling in a case where the fuel tank <NUM> of the FCV <NUM> is filled with the hydrogen gas is measured by the dispenser <NUM>.

During such filling, as the filling amount calculation step (S112), the filling amount calculator <NUM> calculates the calculated filling amount Mc by subtracting the first weight N1 from the weight Nt of the hydrogen gas in the fuel tank <NUM> at the present time. Since Nt = N1 is obtained at the start of filling, the calculated filling amount Mc is <NUM>. Since Nt = N2 is obtained after the start of filling, the calculated filling amount Mc after the start of filling becomes a value obtained by subtracting the first weight N1 from the second weight N2 (that is, Mc = N2 - N1).

Similarly, during the filling, as the filling amount measurement step (S114), the dispenser <NUM> measures the measured filling amount Mm of the hydrogen gas using the Coriolis-type flowmeter <NUM>. Specifically, the flowmeter <NUM> measures the mass flow rate at the moment of filling, and generates a pulse for every <NUM>, for example, which is a minute flow rate unit. A pulse signal is output to the control circuit <NUM>.

The control circuit <NUM> calculates the measured filling amount Mm by counting the pulses input from the start of filling and integrating the mass flow rate. The measured filling amount Mm is output to the control circuit <NUM>, received by the dispenser information receiver <NUM>, and stored in the storage device <NUM> together with the measured time t. The measured filling amount Mm at the start of filling is <NUM>.

Similarly, during the filling, as the filling amount error calculation step (S116), the filling amount error calculator <NUM> 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) at which the calculated filling amount Mc is calculated. At the start of filling, since both the measured filling amount Mm and the calculated filling amount Mc are zero, the filling amount error ΔM is also zero.

Similarly, during the filling, as the determination step (S118), the determiner <NUM> determines the presence or absence of a failure of the flowmeter <NUM> using the filling amount error ΔM. Specifically, the determiner <NUM> determines whether or not the filling amount error ΔM is within a range of a lower limit allowable value α1 or more and an upper limit allowable value α2 or less. When the filling amount error ΔM deviates from the range of the lower limit allowable value α1 or more and the upper limit allowable value α2 or less (NO in S118), the process proceeds to the alarm output step (S120). When the filling amount error ΔM is within the range of the lower limit allowable value α1 or more and the upper limit allowable value α2 or less (YES in S118), the process proceeds to the determination step (S126).

As the alarm output step (S120), when it is determined that the flowmeter <NUM> fails, the outputter <NUM> outputs an alarm indicating the failure of the flowmeter <NUM> to the dispenser <NUM> during the filling with the hydrogen gas. As an example of the alarm, in the dispenser <NUM>, the alarm lamp <NUM> indicating the failure of the flowmeter <NUM> is turned on.

Similarly, during the filling, as the determination step (S126), the determiner <NUM> determines whether or not the pressure of the fuel tank <NUM> has reached the target pressure Pg. When the pressure of the fuel tank <NUM> reaches the target pressure Pg (YES in S126), the process proceeds to the filling stop processing step (S128). When the pressure of the fuel tank <NUM> does not reach the target pressure Pg (NO in S126), the filling is continued, and the process returns to the FCV information reception step (S102). Until the pressure of the fuel tank <NUM> reaches the target pressure Pg, each step from the FCV information reception step (S102) to the determination step (S118) is repeated during the filling.

Summarizing the above, the dispenser <NUM> repeatedly measures the measured filling amount Mm of the hydrogen gas during the filling by using the flowmeter <NUM>. At the same time, the filling amount calculator <NUM> repeatedly calculates the calculated filling amount Mc of the hydrogen gas from the dispenser <NUM> to the fuel tank <NUM> using the information of the pressure Pt, the temperature Tt, and the capacity V of the fuel tank <NUM> during the filling. The filling amount error calculator <NUM> repeatedly calculates the filling amount error ΔM by subtracting the calculated filling amount Mc from the measured filling amount Mm at the same timing when the calculated filling amount Mc is calculated.

Then, the determiner <NUM> compares the calculated filling amount Mc with the measured filling amount Mm during the filling, and repeatedly determines the presence or absence of a failure of the flowmeter <NUM>. That is, the determiner <NUM> determines whether or not the filling amount error ΔM obtained by subtracting the calculated filling amount Mc from the measured filling amount Mm is within a range of the lower limit allowable value α1 or more and the upper limit allowable value α2 or less. Then, when the failure of the flowmeter <NUM> occurs, the dispenser <NUM> outputs an alarm by turning on the alarm lamp <NUM> or the like. In a short period during the filling, a large variation in the filling amount error ΔM may hardly occur. However, the control circuit <NUM> can detect a sudden large change (shift) in the filling amount error ΔM.

As the filling stop processing step (S128), when the pressure of the fuel tank <NUM> reaches the target pressure Pg, the filling with the hydrogen gas is stopped, and the filling processing ends. Specifically, when the pressure measured by the pressure gauge <NUM> in the vicinity of the outlet of the dispenser <NUM> reaches the target pressure Pg, the dispenser controller <NUM> assumes that the pressure of the fuel tank <NUM> reaches the target pressure Pg, and closes the shut-off valves <NUM> and <NUM> in the dispenser <NUM>. In addition, the valve controller <NUM> outputs control signals to the valves <NUM>, <NUM>, and <NUM> via the communication control circuit <NUM>, and controls each valve so as to be closed.

Next, as the recording/calculation step (S130), the recorder/calculator <NUM> calculates a final measured filling amount Mmf at the end of filling measured using the flowmeter <NUM> and a final calculated filling amount Mcf at the end of filling, and stores the final measured filling amount and the final calculated filling amount in the storage device <NUM> in association with data of the filling date and time as result data. 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. In addition, the recorder/calculator <NUM> calculates the final filling amount error ΔMf (= Mmf - Mcf) at the end of filling, and stores the final filling amount error in the storage device <NUM> in association with the data of the filling date and time as the result data, similarly to the above.

From this, a plurality of pieces of result data is accumulated in the storage device <NUM> by repeatedly filling an unspecified number of FCVs <NUM> with the hydrogen gas. As a result, the storage device <NUM> stores a plurality of pieces of past result data in which the final measured filling amount Mmf, the final calculated filling amount Mcf, and the final filling amount error ΔMf are associated. Here, a case where the final filling amount error ΔMf is stored as a plurality of error values is illustrated.

As the average error calculation step (S132), the average error calculator <NUM> reads the final filling amount error ΔMf for each past hydrogen filling accumulated in the storage device <NUM>, and calculates an average filling amount error ΔMave = ΣΔMf/the number of fillings.

As the difference calculation step (S134), the error difference value calculator <NUM> calculates an error difference value Mx which is a difference between a statistical value of a plurality of error values based on a plurality of pieces of past result data and an error value in current hydrogen gas filling. Specifically, the error difference value calculator <NUM> calculates the error difference value Mx by subtracting the current final filling amount error ΔMf from the average filling amount error ΔMave.

As the determination step (S136), the determiner <NUM> compares the statistical value of the plurality of error values based on the plurality of past result data stored in the storage device <NUM> with the error value at the end of the current hydrogen gas filling, determines the presence or absence of a failure of the flowmeter <NUM>, and outputs a result.

In the present embodiment, the presence or absence of the failure of the flowmeter <NUM> is determined based on whether or not the error difference value Mx is within an allowable range. Specifically, the determiner <NUM> determines whether or not the error difference value Mx is within a range of a lower limit allowable value β1 or more and an upper limit allowable value β2 or less. When the error difference value Mx deviates from the range of the lower limit allowable value β1 or more and the upper limit allowable value β2 or less (NO in S136), the process proceeds to the alarm output step (S138). When the error difference value Mx is within the range of the lower limit allowable value β1 or more and the upper limit allowable value β2 or less (YES in S136), the present flow ends.

As the alarm output step (S138), when it is determined that the flowmeter <NUM> fails, the outputter <NUM> outputs an alarm indicating the failure of the flowmeter <NUM> to the dispenser <NUM> during the filling with hydrogen gas. As an example of the alarm, in the dispenser <NUM>, the alarm lamp <NUM> indicating the failure of the flowmeter <NUM> is turned on.

In the example described above, the average filling amount error ΔMave is used as the statistical value of the plurality of error values based on the plurality of pieces of past result data, but the present invention is not limited thereto. Instead of the average value, for example, a median value may be used.

The respective values of the lower limit allowable values α1 and β1 and the upper limit allowable values α2 and β2 may be appropriately set. Since the deviation occurs due to the expansion of the fuel tank <NUM> described above in the calculated filling amount by the PVT method, the difference between the measured filling amount and the calculated filling amount by the PVT method is not generally <NUM>, and there is a predetermined offset amount. In consideration of this point, the respective values of the lower limit allowable values α1 and β1 and the upper limit allowable values α2 and β2 may be set.

As illustrated in <FIG>, instead of the determination step (S118) and the alarm output step (S120) described above, a determination step (S119), an alarm output step (S121), a determination step (S122), and an alarm output step (S123) may be performed as a modification. Similarly, as illustrated in <FIG>, instead of the determination step (S136) and the alarm output step (S138) described above, a determination step (S140), an alarm output step (S141), a determination step (S142), and an alarm output step (S143) may be performed as a modification.

As the determination step (S119), the determiner <NUM> determines whether or not the filling amount error ΔM at the present time is the lower limit allowable value α1 or more. When the filling amount error ΔM is the lower limit allowable value α1 or more (YES in S119), the process proceeds to the determination step (S122). When the filling amount error ΔM is not the lower limit allowable value α1 or more (NO in S119), the process proceeds to the alarm output step (S121).

As the alarm output step (S121), when the filling amount error ΔM is not the lower limit allowable value α1 or more, the outputter <NUM> outputs an alarm <NUM> indicating the failure of the flowmeter <NUM> to the dispenser <NUM> during the filling with the hydrogen gas. As an example of the alarm, in the dispenser <NUM>, the alarm lamp <NUM> indicating the failure of the flowmeter <NUM> is turned on.

As the determination step (S122), the determiner <NUM> determines whether or not the filling amount error ΔM is the upper limit allowable value α2 or less. When the filling amount error ΔM is the upper limit allowable value α2 or less (YES in S122), the process proceeds to the determination step (S126). When the filling amount error ΔM is not the upper limit allowable value α2 or less (NO in S122), the process proceeds to the alarm output step (S123).

As the alarm output step (S123), when the filling amount error ΔM is not the upper limit allowable value α2 or less, the outputter <NUM> outputs an alarm <NUM> indicating the failure of the flowmeter <NUM> to the dispenser <NUM> during the filling with the hydrogen gas. As an example of the alarm, in the dispenser <NUM>, the alarm lamp <NUM> indicating the failure of the flowmeter <NUM> is turned on.

As described above, in the determination processing during the filling, when the filling amount error ΔM is not the upper limit allowable value α2 or less, either or both of the failure of the flowmeter <NUM> and the leakage of the pipe from the flowmeter <NUM> to the fuel tank <NUM> are considered as the cause. On the other hand, when the filling amount error ΔM is not the lower limit allowable value α1 or more, the failure of the flowmeter <NUM> can be specified. Therefore, the determination processing is divided into the upper limit and the lower limit, and the contents of the alarm are separated, so that a failure location can be easily specified.

Similarly, as illustrated in <FIG>, as the determination step (S140), the determiner <NUM> determines whether or not the calculated error difference value Mx is the lower limit allowable value β1 or more. When the error difference value Mx is the lower limit allowable value β1 or more (YES in S140), the process proceeds to the determination step (S142). When the error difference value Mx is not the lower limit allowable value β1 or more (NO in S140), the process proceeds to the alarm output step (S141).

As the alarm output step (S141), when the error difference value Mx is not the lower limit allowable value β1 or more, the outputter <NUM> outputs an alarm <NUM> indicating the failure of the flowmeter <NUM> to the dispenser <NUM> during the filling with the hydrogen gas. As an example of the alarm, in the dispenser <NUM>, the alarm lamp <NUM> indicating the failure of the flowmeter <NUM> is turned on.

As the determination step (S142), the determiner <NUM> determines whether or not the calculated error difference value Mx is the upper limit allowable value β2 or less. When the error difference value Mx is the upper limit allowable value β2 or less (YES in S142), the processing ends. When the error difference value Mx is not the upper limit allowable value β2 or less (NO in S142), the process proceeds to the alarm output step (S143).

As the alarm output step (S143), when the error difference value Mx is not the upper limit allowable value β2 or less, the outputter <NUM> outputs an alarm <NUM> indicating the failure of the flowmeter <NUM> to the dispenser <NUM> during the filling with the hydrogen gas. As an example of the alarm, in the dispenser <NUM>, the alarm lamp <NUM> indicating the failure of the flowmeter <NUM> is turned on.

As described above, in the determination processing at the end of filling, when the error difference value Mx is not the upper limit allowable value β2 or less, either or both of the failure of the flowmeter <NUM> and the leakage of the pipe from the flowmeter <NUM> to the fuel tank <NUM> are considered as the cause. On the other hand, when the error difference value Mx is not the lower limit allowable value β1 or more, the failure of the flowmeter <NUM> can be specified. Therefore, the determination processing is divided into the upper limit and the lower limit, and the contents of the alarm are separated, so that a failure location can be easily specified.

Note that the filling amount of the hydrogen gas in each of the accumulators <NUM>, <NUM>, and <NUM> is reduced by the filling operation described above. Therefore, next, the pressure recovery mechanism <NUM> recovers the pressure in each of the accumulators <NUM>, <NUM>, and <NUM>. The pressure recovery mechanism <NUM> includes the compressor <NUM>, the valves <NUM>, <NUM>, and <NUM>, and the like. First, the system controller <NUM> selects a supply source of the hydrogen gas to be connected to the suction side of the compressor <NUM> from a cylinder, an intermediate accumulator, a hydrogen trailer, or a hydrogen production apparatus (none of which are illustrated in the drawings). Then, under the control of the system controller <NUM>, the pressure recovery controller <NUM> controls the pressure recovery mechanism <NUM>, and recovers the pressure in each of the accumulators <NUM>, <NUM>, and <NUM>.

Specifically, the following operation is performed. In the accumulator of each bank used for filling of the fuel tank <NUM>, the pressure may also be recovered during the filling. However, since there is not enough time to recover the pressure to a prescribed pressure, the pressure should be recovered after the filling. Since the 1st bank, the 2nd bank, and the 3rd bank are switched in this order, first, the pressure of the accumulator <NUM> to be the 1st bank is recovered. The valve controller <NUM> opens the valve <NUM> from a state where the valves <NUM>, <NUM>, and <NUM> are closed.

Then, the compressor controller <NUM> drives the compressor <NUM>, sends the hydrogen gas of the low pressure (for example, <NUM> MPa) from the supply source of the hydrogen gas while compressing the hydrogen gas, and fills the accumulator <NUM> with the hydrogen gas until the pressure of the accumulator <NUM> reaches a predetermined pressure P0 (for example, <NUM> MPa), thereby recovering the pressure of the accumulator <NUM>.

Next, the valve controller <NUM> closes the valve <NUM> and opens the valve <NUM> instead. Then, the compressor controller <NUM> drives the compressor <NUM>, sends the hydrogen gas of the low pressure (for example, <NUM> MPa) while compressing the hydrogen gas, and fills the accumulator <NUM> with the hydrogen gas until the pressure of the accumulator <NUM> reaches the predetermined pressure P0 (for example, <NUM> MPa), thereby recovering the pressure of the accumulator <NUM>.

In this way, even when a next FCV <NUM> arrives at the hydrogen station <NUM>, the hydrogen gas can be supplied similarly.

As described above, according to the present embodiment, the accuracy of the flowmeter <NUM> can be continuously verified. Therefore, it is possible to avoid performing the filling operation while using the failed flowmeter <NUM>.

Next, another example of calculating the calculated filling amount Mc in the filling amount error calculation step (S116) described above will be described. In the filling amount error calculation step (S116) described above, the capacity V of the fuel tank <NUM> used when the calculated filling amount Mc is calculated is a predetermined value unique to the FCV <NUM>, and the expansion rate of the fuel tank <NUM> is not particularly considered. Therefore, since the deviation occurs in the calculated filling amount by the PVT method due to the expansion of the fuel tank <NUM> described above, the difference between the measured filling amount and the calculated filling amount by the PVT method is not generally <NUM>, and there is a predetermined offset amount.

As a result of intensive studies by the inventors of the present application, it has been found that the deviation due to expansion of the fuel tank <NUM> is not always the same, and 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 <NUM> shows filling data acquired when hydrogen is filled in the hydrogen station <NUM> a plurality of times.

As the filling data, the measured filling amount Mm, the first pressure P1, the second pressure P2, the first temperature T1, and the second temperature T2 are shown. The second pressure P2 and the second temperature T2 are data at the end of filling. In addition, the control circuit <NUM> calculates the calculated filling amount Mc, subtracts the calculated filling amount Mc from the measured filling amount Mm, and calculates the filling amount error ΔM. The percentage error shown in Table <NUM> is a value of <NUM> × (filling amount error ΔM/measured filling amount Mm).

<FIG> is a graph illustrating a relation between a differential pressure at the time of filling and a filling amount error in each filling data in Table <NUM>. A horizontal axis of the graph illustrated in <FIG> represents the differential pressure [MPa] at the time of filling, which is obtained by subtracting the first pressure P1 from a standard pressure Ps of the fuel tank <NUM> at the end of filling. As the standard pressure Ps, an average value of the second pressure P2 at the end of filling included in a plurality of pieces of filling data acquired in the past can be used. Further, the filling amount error with respect to the differential pressure at the time of filling calculated assuming that the average value of the second pressure P2 at the end of filling is the standard pressure Ps is plotted as illustrated in <FIG>, and then the standard pressure Ps corrected such that a determination coefficient R<NUM> of an approximate expression y approaches <NUM> may be used. A known fitting method or the like can be used to correct the standard pressure Ps. Since the standard pressure Ps can also vary depending on the outside air temperature, the standard pressure Ps may be statistically calculated for each season with a different outside air temperature. A specific value of the standard pressure Ps is <NUM> [MPa] in the fuel tank in one example. A vertical axis of the graph illustrated in <FIG> represents the filling amount error ΔM [kg].

As illustrated in <FIG>, the filling amount error ΔM increases as the differential pressure at the time of filling increases, and the relation represented by the expression y is obtained. Therefore, it has been found that there is a high correlation between the differential pressure at the time of filling and the filling amount error. The expression y and the standard pressure Ps are values suitable for a case of a certain type of fuel tank. However, if the expression y is statistically calculated for each type of fuel tank or each vehicle type, various FCVs <NUM> arriving at the hydrogen station <NUM> can be handled.

Therefore, based on the result illustrated in <FIG>, the calculated filling amount Mc is calculated using a value in which the expansion rate of the tank is considered as the capacity of the tank used in the PVT method. Specifically, the first function indicating the first capacity V1 of the fuel tank <NUM> in the filling amount calculation before the start of filling is V1 = Vs + (Vs × Ex) × (P1/Ps)<NUM>, when the standard capacity unique to the tank is set to Vs and the expansion rate is set to Ex. In the first function, a correction amount of the tank capacity according to the expansion rate Ex is proportional to the cube of the first pressure P1. In addition, the second function indicating the second capacity V2 of the fuel tank <NUM> in the filling amount calculation after the start of filling is V2 = Vs + (Vs × Ex) × (P2/Ps)<NUM>. In the second function, a correction amount of the tank capacity according to the expansion rate Ex is proportional to the cube of the second pressure P2. Note that the expansion rate Ex and the standard capacity Vs are set according to the type of the fuel tank <NUM> with reference to the result illustrated in <FIG> described above, for example, and are stored in the storage device <NUM> in advance. Instead of setting the first function and the second function as the mathematical expressions, the first function and the second function may be stored in the storage device <NUM> in advance as a table according to parameters such as the first pressure P1 and the second pressure P2 of the fuel tank. The second function may be V2 = Vs + (Vs × Ex) × (P2/Ps)<NUM>. 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.

Next, a flowmeter failure determination method using the first capacity V1 and the second capacity V2 in which the expansion rate of the fuel tank <NUM> is considered will be described. An outline of a hydrogen gas filling method including the determination method is substantially the same as that in the flowcharts illustrated in <FIG> and <FIG> described above. A difference is to use the first capacity V1 and the second capacity V2 in which the expansion rate of the fuel tank <NUM> is considered in the process of calculating the calculated filling amount Mc used in the filling amount error calculation step (S116).

Specifically, the flowmeter failure determination method according to the present embodiment includes: a step (S114) of measuring a filling amount (measured filling amount Mm) of hydrogen gas filled in a fuel tank <NUM> using a flowmeter <NUM>; a step (S102) of acquiring information of a pressure P and a temperature T of the fuel tank <NUM>; a step (S112) of calculating a filling amount (calculated filling amount Mc) of the hydrogen gas filled in the fuel tank <NUM> based on the acquired pressure P and temperature T and the capacity V of the fuel tank <NUM> in which an expansion rate Ex of the fuel tank <NUM> is considered; and a step (S118) of determining presence or absence of a failure of the flowmeter <NUM> 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).

As a result, in the step (S112) of calculating the filling amount, when the calculated filling amount Mc is calculated from the information of the pressure P, the temperature T, and the capacity V of the fuel tank <NUM>, the expansion rate Ex of the tank is considered, so that the accuracy of the calculated filling amount Mc is improved. In other words, since the filling amount error ΔM between the measured filling amount Mm and the calculated filling amount Mc is small and the variation is small, the accuracy of failure determination of the flowmeter <NUM> is improved. 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 or not the filling amount of the hydrogen gas is correctly measured for each filling. The filling amount error ΔM may be calculated in the middle of filling before the end of filling, and the validity of the filling amount error ΔM in the middle of filling may be evaluated. By evaluating the validity of the filling amount error ΔM in the middle of the filling, it is possible to detect a defect occurring in the middle of the filling at an early stage.

The flowmeter failure determination method according to the present embodiment includes an alarm output step (S120, S121, and S123) of outputting a determination result. In the example described above, the alarm lamp is turned on, but the type of the alarm is not limited thereto. In the alarm output step, a signal for operating a reporter (display panel, sound output, alarm lamp, and the like) of the dispenser <NUM> including the flowmeter <NUM> may be output. In the alarm output step, a signal for reporting an alarm to an observer or a monitoring device performing monitoring at a remote place may be output via a network.

The calculated filling amount Mc is calculated by Mc = N2 - N1 using the first weight N1 = ρ(P1, T1) × V1 calculated from the first pressure P1, the first temperature T1, and the first capacity V1 of the fuel tank <NUM> before the start of filling and the second weight N2 = ρ(P2, T2) × V2 calculated from the second pressure P2, the second temperature T2, and the second capacity V2 of the fuel tank <NUM> after the start of filling (S112). As described above, the first capacity V1 and the second capacity V2 of the fuel tank <NUM> can be calculated using the first function and the second function expressed by the mathematical expressions stored in the storage device <NUM>. As a result, it is possible to perform failure determination by simple calculation based on information from the pressure gauge <NUM> or the thermometer <NUM> of the fuel tank <NUM>.

Here, the first function and the second function are different. In a situation where the pressure in the fuel tank <NUM> before the start of filling is relatively low, the capacity in which the expansion rate of the fuel tank <NUM> is considered can be accurately calculated using the first function. On the other hand, in a situation where the pressure in the fuel tank <NUM> after the start of filling is relatively high, the capacity in which the expansion rate of the fuel tank <NUM> is considered can be accurately calculated using the second function. That is, in the first function, the tank capacity according to the expansion rate is corrected based on the first pressure P1, and in the second function, the tank capacity according to the expansion rate is corrected based on the second pressure P2. Therefore, the capacity of the fuel tank <NUM> can be calculated with higher accuracy than when it is assumed that the correction amount according to the expansion rate is constant regardless of the pressure in the tank. In addition, since the filling amount error ΔM can be more appropriately calculated for each filling by incorporating a correction function in which the expansion rate is considered into a calculation formula of the calculated filling amount Mc, the failure determination of the flowmeter <NUM> can be easily performed in a short time. In other words, even if a plurality of pieces of past result data necessary for the calculation of the average filling amount error ΔMave is not accumulated, the failure determination of the flowmeter <NUM> can be accurately performed.

The first capacity V1 before the start of filling is calculated by a first function (V1 = V + (V × Ex) × (P1/Ps)<NUM>) that is non-linear with respect to the first pressure P1. As a reason why such a function is preferable, the inventors of the present application have focused on the fact that a deviation (that is, the filling amount error ΔM) between the measured filling amount Mm and the calculated filling amount Mc is large in a situation where the filling amount of the fuel tank <NUM> is large (a situation where the difference between the first pressure P1 and the second pressure P2 is large). Since the first pressure P1 of the fuel tank <NUM> depends on a consumption amount of the hydrogen gas according to a travel distance of the FCV <NUM> arriving at the hydrogen station <NUM>, the first pressure P1 has a large variation according to the situation. On the other hand, the second pressure P2 of the fuel tank <NUM> has a small variation according to the situation. Therefore, the situation in which the filling amount of the fuel tank <NUM> is large can be said to be a situation in which the first pressure P1 of the fuel tank <NUM> is small. By using a non-linear function with respect to the acquired information of the pressure (first pressure P1) in the tank as the first function in which the first pressure P1 is considered, the capacity of the fuel tank <NUM> can be calculated with higher accuracy than a case where it is assumed that the expansion rate increases in proportion to the pressure in the tank. This is particularly effective when the first pressure P1 is small, and the filling amount is large.

On the other hand, the second function in which the second pressure P2 is considered may use a non-linear function or a linear function with respect to the acquired pressure (second pressure P2) in the tank. Since the second pressure P2 at the end of filling has a smaller variation according to the situation than the first pressure P1, the filling amount error ΔM2 can be accurately calculated even when a value of (P2/Ps) is cubed and corrected or even when the value is raised to the first power and corrected. However, as a result of the evaluation using actual data, in the second function in which the second pressure P2 at the end of filling is considered, a result in which the value is preferably raised to the first power and corrected is obtained. Since the second pressure P2 in the middle of filling has a larger variation according to the situation than when the filling ends, it may be desirable to use a non-linear function in which the value of (P2/Ps) is cubed and corrected when the second weight N2 in the middle of filling is calculated.

The control circuit <NUM> (specifically, the receiver <NUM>) may acquire information regarding the type of the fuel tank <NUM> from the FCV <NUM>. The control circuit <NUM> may acquire information regarding the vehicle type from the FCV <NUM> and specify the type of the fuel tank <NUM> corresponding to the vehicle type. The storage device <NUM> may store in advance a table that associates the vehicle type with the type of the fuel tank. The first function and the second function related to the first capacity V1 or the second capacity V2 may be set according to the type of the fuel tank <NUM>. As a result, it is possible to determine the failure of the flowmeter <NUM> when fuel tanks of various vehicle types are filled with the hydrogen gas.

As described above, according to the failure determination method according to the present embodiment, the accuracy of the dispenser <NUM>, more specifically, the flowmeter <NUM> in the hydrogen station <NUM> can be verified. In addition, it is possible to continuously verify the accuracy of the flowmeter <NUM> every time the FCV <NUM> is filled with the hydrogen gas without closing the hydrogen station <NUM>.

A hydrogen filling apparatus <NUM> according to the present embodiment includes: a measurer (dispenser <NUM>) that measures a filling amount (measured filling amount Mm) of hydrogen gas filled in a fuel tank <NUM> of an automobile using a flowmeter <NUM>; an acquirer (receiver <NUM>) that acquires information of a pressure P and a temperature T of the fuel tank <NUM>; a filling amount calculator <NUM> that calculates a filling amount (calculated filling amount Mc) of the hydrogen gas filled in the fuel tank <NUM> from the measurer (dispenser <NUM>) based on the acquired pressure P and temperature T and the capacity V of the fuel tank <NUM> in which an expansion rate Ex of the fuel tank <NUM> is considered; and a determiner <NUM> that determines the presence or absence of a failure of the flowmeter <NUM> using an error value (filling amount error ΔM) between the filling amount (measured filling amount Mm) measured using the flowmeter <NUM> and the calculated filling amount (calculated filling amount Mc).

Although the present invention has been described above with reference to the above-described embodiments, the present invention is not limited to the above-described embodiments, and structures obtained by appropriately combining or replacing the structures illustrated in the embodiments are also included in the present invention. In addition, it is also possible to appropriately rearrange the combinations or the order of processing in the embodiments based on the knowledge of those skilled in the art and to add modifications such as various design changes to the embodiments, and the embodiments to which such modifications are added can also be included in the scope of the present invention.

The present invention relates to failure determination technology of a measurer included in a hydrogen filling apparatus.

Claim 1:
A hydrogen filling apparatus (<NUM>) comprising:
a measurer (<NUM>) structured to measure a filling amount of hydrogen gas filled in a fuel tank (<NUM>) of an automobile (<NUM>), using a flowmeter (<NUM>);
an acquirer (<NUM>) structured to acquire information of a pressure and a temperature of the fuel tank (<NUM>);
a filling amount calculator (<NUM>) structured to calculate the filling amount of the hydrogen gas filled in the fuel tank (<NUM>) from the measurer (<NUM>) based on the acquired pressure and temperature and a capacity of the fuel tank (<NUM>); and
a determiner (<NUM>) structured to determine presence or absence of a failure of the flowmeter (<NUM>) using an error value (ΔM) between the measured filling amount (Mm) using the flowmeter and the calculated filling amount (MC), characterised in that the expansion rate of the fuel tank (<NUM>) is considered in the calculation of the filling amount of the hydrogen gas in said fuel tank (<NUM>).