Patent Description:
The present invention relates to a hydrogen gas filling method and a hydrogen gas filling device, for example, a hydrogen gas filling method and a hydrogen gas filling device for a vehicle powered by hydrogen gas at a hydrogen station.

As fuel for vehicles, in addition to conventional fuel oils such as gasoline, recently, hydrogen fuel has attracted attention as a clean energy source. As a result, fuel cell vehicles (FCVs) powered by the hydrogen gas have been developed. In order to popularize the fuel cell vehicle (FCV), it is necessary to expand hydrogen stations capable of rapidly filling the fuel cell vehicle with the hydrogen gas. At the hydrogen station, in order to rapidly fill the FCV with the hydrogen gas, a multi-stage accumulator including a plurality of accumulators for accumulating the hydrogen fuel compressed to a high pressure by a compressor is disposed. By performing filling via a dispenser (meter) while switching the accumulator to be used, a differential pressure between a pressure inside the accumulator and a pressure of a fuel tank of the FCV is greatly maintained, and the FCV is rapidly filled with the hydrogen gas by the differential pressure from the accumulator to the fuel tank (for example, refer to Patent Literature <NUM>).

Here, in the case of filling the hydrogen gas at the hydrogen station, a filling time until full filling is estimated by a simulation with a large margin in advance for an actual temperature increase of the fuel tank so that the temperature of the fuel tank of the FCV does not become a high temperature, by using the hydrogen gas that is cooled enough to prevent the supply temperature of the hydrogen gas from increasing. Then, a filling speed is determined according to the estimated filling time. Therefore, the determined filling speed is generally set lower as compared with the actual filling capacity of the hydrogen station. Therefore, a wasted filling time is required. Further, in order to prevent the supply temperature of the supplied hydrogen gas from increasing, a cooler (precooler) in the dispenser is constantly supplied with a refrigerant from a refrigerator, and the hydrogen gas is cooled to, for example, -<NUM>. Therefore, a large amount of electric power is required to circulate the refrigerant.

Patent Literature <NUM>: <CIT> <CIT> relates to a method for controlling a fuel cell vehicle. <CIT> discloses a hydrogen station.

The present invention provides a method and a device capable of filling hydrogen gas at a filling speed where an extra margin is eliminated, when the hydrogen gas is filled.

According to one aspect of the present invention, a hydrogen gas filling method in accordance with independent claim <NUM> is provided.

According to another aspect of the present invention, a hydrogen gas filling device in accordance with independent claim <NUM> is provided.

According to one aspect of the present invention, when hydrogen gas is filled, the hydrogen gas can be filled at a filling speed where an extra margin is eliminated Therefore, a filling time can be shortened.

<FIG> is an example of a configuration diagram showing a configuration of a hydrogen filling system of a hydrogen station in an embodiment <NUM>. In <FIG>, a hydrogen filling system <NUM> is disposed in a hydrogen station <NUM>. The hydrogen filling system <NUM> includes a multi-stage accumulator <NUM>, a dispenser (measuring machine) <NUM>, a compressor <NUM>, a refrigerator <NUM>, and a control circuit <NUM>. The multi-stage accumulator <NUM> includes a plurality of accumulators <NUM>, <NUM>, and <NUM> in which a use lower limit pressure is set to multiple levels. In the example of <FIG>, the three accumulators <NUM>, <NUM>, and <NUM> configure the multi-stage accumulator <NUM>. In the example of <FIG>, 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, for example. The accumulator <NUM> functions as a 3rd bank having a high use lower limit pressure, for example. However, the present invention is not limited thereto. The accumulators used in the 1st bank to the 3rd bank are replaced as needed. In the hydrogen station <NUM>, a curdle, an intermediate accumulator, and/or a hydrogen production apparatus (not shown) are also disposed. Further, a hydrogen trailer (not shown) for filling and delivering hydrogen gas arrives at the inside of the hydrogen station <NUM>.

Further, in <FIG>, the suction side of the compressor <NUM> is connected to the curdle, 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.

Further, the accumulator <NUM> is connected to the dispenser <NUM> via a valve <NUM> by a pipe. Further, the accumulator <NUM> is connected to the dispenser <NUM> via a valve <NUM> by a pipe. Further, 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>. Further, 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 fuel supplied from the multi-stage accumulator <NUM> per unit time is controlled by the flow rate adjustment valve <NUM>, and is measured by the flowmeter <NUM>. Then, the hydrogen fuel is cooled to, for example, -<NUM> by the cooler <NUM>. The cooled hydrogen fuel passes through the shut-off valve <NUM>, the emergency detachment coupler <NUM>, and the nozzle <NUM>, and a fuel tank <NUM> mounted on an FCV <NUM> is filled with the hydrogen fuel by using a differential pressure. Further, a refrigerant cooled by the refrigerator <NUM> is circulated in the cooler <NUM> by a circulation pump (not shown). Further, the control circuit <NUM> is configured to be able to communicate with an on-board device <NUM> in the FCV <NUM> (fuel cell vehicle (FCV) powered by the hydrogen fuel) that has arrived at the hydrogen station <NUM>. For example, the control circuit <NUM> is configured to be able to perform wireless communication using infrared rays. Further, the control circuit <NUM> is connected to the control circuit <NUM> that controls the entire hydrogen filling system <NUM>.

Further, 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 an 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>. Further, in the dispenser <NUM>, a pressure near an inlet of the dispenser <NUM> supplied to the dispenser <NUM> is measured by a pressure gauge <NUM>. Further, a pressure near the outlet of the dispenser <NUM> is measured by a pressure gauge <NUM>. In the example of <FIG>, the pressure gauge <NUM> measures a pressure of the upstream side (primary side) of the shut-off valve <NUM> located on the primary side of the cooler <NUM>. The pressure gauge <NUM> measures a pressure near 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 seconds). In other words, the control circuit <NUM> monitors the pressure measured by each pressure gauge at all times or at a predetermined sampling cycle (for example, <NUM> msec to several seconds). Further, a pressure of the fuel tank <NUM> mounted on the FCV <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> mounted on the FCV <NUM> is monitored at all times or at predetermined sampling intervals (for example, <NUM> msec to several seconds) while the communication between the on-board device <NUM> and the control circuit <NUM> is established.

Further, in the dispenser <NUM>, a temperature near the outlet of the dispenser <NUM> of the hydrogen gas supplied to the FCV <NUM> is measured by a thermometer <NUM>. The thermometer <NUM> is on the secondary side of the cooler <NUM>, and measures a temperature near the emergency detachment coupler <NUM>, for example. Further, an outside air temperature near the dispenser <NUM> is measured by a 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 tens of seconds). In other words, the control circuit <NUM> monitors the temperature measured by each thermometer at all times or at a predetermined sampling cycle (for example, <NUM> msec to several tens of seconds). Further, a temperature of the fuel tank <NUM> mounted on the FCV <NUM> is measured by a thermometer <NUM> mounted on the FCV <NUM>. As will be described later, the temperature of the fuel tank <NUM> mounted on the FCV <NUM> is monitored at all times or at predetermined sampling intervals (for example, <NUM> msec to several seconds) while the communication between the on-board device <NUM> and the control circuit <NUM> is established.

In a state where the hydrogen gas accumulated in the curdle, the intermediate accumulator, or the tank of the hydrogen trailer is decompressed to a low pressure (for example, <NUM> MPa) by each regulator (not shown) controlled by the control circuit <NUM>, the hydrogen gas is supplied to the suction side of the compressor <NUM>. Similarly, the hydrogen gas produced by the hydrogen production apparatus is supplied to the suction side of the compressor <NUM> at a low pressure (for example, <NUM> MPa). Under the control of the control circuit <NUM>, the compressor <NUM> supplies the hydrogen gas supplied at low pressure to the accumulators <NUM>, <NUM>, and <NUM> of the multi-stage accumulator <NUM> while compressing the hydrogen gas. The compressor <NUM> performs compression until the internal pressure of each of the accumulators <NUM>, <NUM>, and <NUM> of the multi-stage accumulator <NUM> becomes a predetermined high pressure (for example, <NUM> MPa). In other words, the compressor <NUM> performs compression until a secondary side pressure POUT of the discharge side becomes a predetermined high pressure (for example, <NUM> MPa). Whether a partner supplying the hydrogen gas to the suction side of the compressor <NUM> is the curdle, the intermediate accumulator, the hydrogen trailer, or the hydrogen production apparatus may be determined by control of the control circuit <NUM>. Similarly, whether a partner to which the compressor <NUM> supplies the hydrogen gas is the accumulator <NUM>, <NUM>, or <NUM> may be determined by controlling opening/closing of the corresponding valves <NUM>, <NUM>, and <NUM> disposed on the respective pipes by the control circuit <NUM>. Alternatively, control may be performed so that the hydrogen gas is supplied to two or more accumulators at the same time.

In the example described above, the case where control is performed so that a pressure PIN for supplying the hydrogen gas to the suction side of the compressor <NUM> is reduced to a predetermined low pressure (for example, <NUM> MPa) has been shown. However, the present invention is not limited thereto. The hydrogen gas accumulated in the curdle, the intermediate accumulator, or the hydrogen trailer may be supplied to the suction side of the compressor <NUM> without reducing the pressure or at a pressure higher than a predetermined low pressure (for example, <NUM> MPa), and may be compressed.

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

<FIG> is a configuration diagram showing an example of an internal configuration of the control circuit that controls the entire hydrogen filling system in the embodiment <NUM>. In <FIG>, a communication control circuit <NUM>, a memory <NUM>, a reception unit <NUM>, an outside air temperature reception unit <NUM>, an end pressure calculation unit <NUM>, a timer <NUM>, a temperature difference calculation unit <NUM>, a filling speed calculation unit <NUM>, a system control unit <NUM>, a determination unit <NUM>, a pressure recovery control unit <NUM>, a supply control unit <NUM>, a bank pressure reception unit <NUM>, dispenser information reception unit <NUM>, an output unit <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 control unit <NUM> has a valve control unit <NUM> and a compressor control unit <NUM>. The supply control unit <NUM> has a dispenser control unit <NUM>, a valve control unit <NUM>, and a refrigerator control unit <NUM>. Each "unit" such as the reception unit <NUM>, the outside air temperature reception unit <NUM>, the end pressure calculation unit <NUM>, the timer <NUM>, the temperature difference calculation unit <NUM>, the filling speed calculation unit <NUM>, the system control unit <NUM>, the determination unit <NUM>, the pressure recovery control unit <NUM> (the valve control unit <NUM> and the compressor control unit <NUM>), the supply control unit <NUM> (the dispenser control unit <NUM>, the valve control unit <NUM>, and the refrigerator control unit <NUM>), the bank pressure reception unit <NUM>, the dispenser information reception unit <NUM>, and the output unit <NUM> includes a processing circuit, and an electric circuit, a computer, a processor, a circuit board, a semiconductor device or the like is included in the processing circuit. Further, a common processing circuit (same processing circuit) may be used for each "unit". Alternatively, a different processing circuit (separate processing circuit) may be used. Input data required in the reception unit <NUM>, the outside air temperature reception unit <NUM>, the end pressure calculation unit <NUM>, the timer <NUM>, the temperature difference calculation unit <NUM>, the filling speed calculation unit <NUM>, the system control unit <NUM>, the determination unit <NUM>, the pressure recovery control unit <NUM> (the valve control unit <NUM> and the compressor control unit <NUM>), the supply control unit <NUM> (the dispenser control unit <NUM>, the valve control unit <NUM>, and the refrigerator control unit <NUM>), the bank pressure reception unit <NUM>, the dispenser information reception unit <NUM>, and the output unit <NUM>, or calculated results are stored in the memory <NUM> each time.

Further, a conversion table <NUM> showing a correlation between FCV information such as the pressure, the temperature, and the volume of the fuel tank <NUM> mounted on the FCV <NUM>, a remaining amount of the hydrogen gas corresponding to the FCV information, and filling information such as a final pressure and a final temperature for filling the fuel tank <NUM> with the hydrogen gas is stored in the storage device <NUM>. Further, a correction table <NUM> for correcting a result obtained from the conversion table <NUM> is stored in the storage device <NUM>.

Further, a relation expression parameter <NUM> between a difference ΔT between a maximum allowable temperature Tmax of the fuel tank <NUM> and an initial temperature Ti of the fuel tank <NUM> and a filling speed M is stored in a storage device <NUM>. Further, a relation table <NUM> between the difference ΔT between the maximum allowable temperature Tmax of the fuel tank <NUM> and the initial temperature Ti of the fuel tank <NUM>, and the filling speed M is stored in the storage device <NUM>. The relation expression parameter <NUM> and the relation table <NUM> are created for each hydrogen gas supply temperature. Further, the relation expression parameter is created depending on an initial pressure Pa of the fuel tank <NUM>. Further, the relation expression parameter is created depending on an outside air temperature T'. In the example of <FIG>, a case where both the relation expression parameter <NUM> and the relation table <NUM> are stored is shown, but only one of them may be stored.

Further, the bank pressure reception unit <NUM> receives the pressure measured by each of the pressure gauges <NUM>, <NUM>, and <NUM> at all times or at a predetermined sampling cycle (for example, <NUM> msec to several seconds), and stores the pressure in the storage device <NUM> together with a reception time. Similarly, the dispenser information reception unit <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 (for example, <NUM> msec to several seconds), and stores the pressure in the storage device <NUM> together with a reception time. Further, the dispenser information reception unit <NUM> receives the temperature measured by the thermometer <NUM> in the dispenser <NUM> at all times or at a predetermined sampling cycle (for example, <NUM> msec to several seconds), and stores the temperature in the storage device <NUM> together with the reception time.

As described above, conventionally, in the case of filling the hydrogen gas at the hydrogen station <NUM>, a filling time until full filling is estimated by a simulation with a large margin in advance for an actual temperature increase of the fuel tank <NUM> so that the temperature of the fuel tank <NUM> of the FCV <NUM> does not become a high temperature, by using the hydrogen gas that is cooled enough to prevent the supply temperature of the hydrogen gas from increasing. Then, a filling speed is determined according to the estimated filling time. Therefore, the determined filling speed is generally set lower as compared with the actual filling capacity of the hydrogen station <NUM>. Therefore, in the embodiment <NUM>, a correlation between a difference between a maximum allowable temperature of the fuel tank <NUM> and an initial temperature of the fuel tank <NUM>, and a filling speed is calculated on the basis of data when the hydrogen gas is actually filled into the fuel tank <NUM> of the FCV <NUM> at the hydrogen station <NUM>, and the filling speed is determined according to the correlation. Hereinafter, it will be specifically described.

<FIG> is a flowchart showing main steps of a hydrogen filling method in the embodiment <NUM>. In <FIG>, the hydrogen filling method in the embodiment <NUM> executes a series of steps such as a nozzle connection step (S102), a refrigerator circulation start step (S104), an FCV information reception step (S106), an outside air temperature reception step (S108), an end pressure calculation step (S110), a temperature difference calculation step (S112), a filling speed calculation step (S114), a hydrogen filling step (S116), a determination step (S118), a hydrogen supply temperature input step (S120), and a refrigerator circulation stop and pressure recovery continuation step (S122).

As the nozzle connection step (S102), 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>. When the FCV <NUM> arrives at the inside of the hydrogen station <NUM> and the nozzle <NUM> of the dispenser <NUM> is connected and fixed to the reception port (receptacle) of the fuel tank <NUM> of the FCV <NUM> by the user or the worker of the hydrogen station <NUM>, communication between the on-board device <NUM> and the control circuit <NUM> (relay device) is established.

As the refrigerator circulation start step (S104), when the communication between the on-board device <NUM> and the control circuit <NUM> (relay device) is established, the refrigerator control unit <NUM> in the control circuit <NUM> controls the refrigerator <NUM> via the communication control circuit <NUM> and drives a circulation pump of the refrigerator <NUM>. In this way, the circulation of the refrigerant between the refrigerator <NUM> and the cooler <NUM> is started. As a result, cooling of the hydrogen gas is started by the cooler <NUM> in the dispenser <NUM>. As described above, the hydrogen gas is cooled by the cooler <NUM> disposed in the dispenser <NUM>. However, in the embodiment <NUM>, when the filling of the hydrogen gas into the fuel tank <NUM> is started, cooling of the hydrogen gas is started by the cooler <NUM> in the dispenser <NUM>, and the circulation of the refrigerant is stopped when the filling of the hydrogen gas into the fuel tank <NUM> is completed, as described later. As described above, conventionally, the circulation pump that is constantly driven by the constant circulation is stopped during a period in which the hydrogen gas is not filled. As a result, it is possible to reduce the consumption of an amount of electric power for driving the circulation pump, which has occurred during the period in which the hydrogen gas is not filled.

As the FCV information reception step (S106), the reception unit <NUM> receives the temperature (initial temperature) Ti of the fuel tank <NUM> before the start of filling from the FCV <NUM> (fuel cell vehicle: FCV) equipped with the fuel tank <NUM> filled with the hydrogen gas and powered by the hydrogen gas. Further, when the reception unit <NUM> receives the temperature Ti of the fuel tank <NUM> before the start of filling, the reception unit <NUM> also receives the pressure (initial pressure) Pa of the fuel tank <NUM> before the start of filling. Specifically, the reception unit <NUM> receives FCV information regarding the fuel tank <NUM> (hydrogen storage container) mounted on the FCV <NUM> from the on-board device <NUM> mounted on the FCV <NUM> (fuel cell vehicle (FCV)) powered by the hydrogen gas. Specifically, the following operation is performed. When the communication between the on-board device <NUM> and the control circuit <NUM> (relay device) is established, the FCV information such as the present pressure and temperature of the fuel tank <NUM> and the volume of the fuel tank <NUM> is output (transmitted) in real time from the on-board device <NUM>. The FCV information is relayed by the control circuit <NUM> and transmitted to the control circuit <NUM>. In the control circuit <NUM>, the reception unit <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 seconds) while the communication between the on-board device <NUM> and the control circuit <NUM> is established. The received FCV information is stored in the storage device <NUM> together with reception time information.

As the outside air temperature reception step (S108), the outside air temperature reception unit <NUM> receives the outside air temperature T' measured by the thermometer <NUM> via the communication control circuit <NUM>. The received information on the outside air temperature T' is stored in the storage device <NUM> together with reception time information.

As the end pressure calculation step (S110), the end pressure calculation unit <NUM> reads the conversion table <NUM> from the storage device <NUM>, and calculates and predicts a final pressure PF corresponding to the pressure Pa, temperature Ti, and volume V of the fuel tank <NUM> at the time of initial reception and the outside air temperature T', which have been received. Further, the end pressure calculation unit <NUM> reads the correction table <NUM> from the storage device <NUM>, and corrects a numerical value obtained by the conversion table <NUM>. When only data of the conversion table <NUM> has a large error in an obtained result, the correction table <NUM> may be provided on the basis of a result obtained by an experiment, a simulation or the like. The calculated final pressure PF is output to the system control unit <NUM>.

In the temperature difference calculation step (S112), the temperature difference calculation unit <NUM> calculates a difference ΔT (= Tmax - Ti) between the preset maximum temperature Tmax and the temperature (initial temperature) Ti of the fuel tank <NUM>. For example, <NUM> is preset as the maximum temperature Tmax allowed in the fuel tank <NUM>. When the received temperature (initial temperature) Ti of the fuel tank <NUM> before filling is, for example, <NUM>, the difference ΔT = <NUM> - <NUM> = <NUM> is calculated.

<FIG> is a diagram showing an example of a correlation between the temperature increase change of the fuel tank and the filling speed in the embodiment <NUM>. In <FIG>, a vertical axis indicates the difference ΔT (°C) between the preset maximum temperature Tmax and the temperature (initial temperature) Ti of the fuel tank <NUM> as the temperature increase change. A horizontal axis indicates the filling speed M (MPa/min). Further, the correlation is created for each hydrogen gas supply temperature. Furthermore, the correlation depends on the pressure (initial pressure) Pa before the start of filling of the fuel tank <NUM> and the outside air temperature T'. Therefore, the correlation is created for each combination of the initial pressure Pa of the fuel tank <NUM> and the outside air temperature T' and for each hydrogen gas supply temperature. In the example of <FIG>, correlations are shown for hydrogen gas supply temperatures of -<NUM>, -<NUM>, -<NUM>, and -<NUM>. The correlation is created on the basis of data when the hydrogen gas is actually filled at the hydrogen station <NUM>. Therefore, a conventional margin is not included in the correlation. In the example of <FIG>, a graph in which a plotted relation is approximated by a quadratic polynomial is shown.

<FIG> is a diagram illustrating a coefficient table of a quadratic polynomial when the correlation between the temperature increase change of the fuel tank and the filling speed is approximated by the quadratic polynomial in the embodiment <NUM>. In <FIG>, values of coefficients a, b, and c of the quadratic polynomial described in <FIG> are defined for each hydrogen gas supply temperature. In the example of <FIG>, a case where the coefficients a, b, and c of the quadratic polynomial are defined for hydrogen gas supply temperatures of -<NUM>, -<NUM>, -<NUM>, -<NUM>, -<NUM>, -<NUM>, and -<NUM> is shown. Hydrogen gas supply temperatures that are not shown in the correlation equation of <FIG> may be obtained by linear interpolation. Further, when hydrogen gas supply temperatures at the time of actual calculation are not defined, linearly interpolated values may be used. The correlation between the difference between the maximum allowable temperature and the initial temperature of the fuel tank, and the filling speed is not limited to the quadratic equation. The correlation may be approximated by equations of other orders.

<FIG> is a diagram showing another example of the correlation between the temperature increase change of the fuel tank and the filling speed in the embodiment <NUM>. In <FIG>, a vertical axis indicates the difference ΔT (°C) between the preset maximum temperature Tmax and the temperature (initial temperature) Ti of the fuel tank <NUM> as the temperature increase change. A horizontal axis indicates the filling speed M (MPa/min). Further, the correlation is created for each hydrogen gas supply temperature, similarly to the case shown in <FIG>. Furthermore, the correlation depends on the pressure (initial pressure) Pa before the start of filling of the fuel tank <NUM> and the outside air temperature T', similarly to the case shown in <FIG>. Therefore, the correlation is created for each combination of the initial pressure Pa of the fuel tank <NUM> and the outside air temperature T' and for each hydrogen gas supply temperature. In the example of <FIG>, correlations are shown for hydrogen gas supply temperatures of -<NUM>, -<NUM>, and -<NUM>. The correlation is created on the basis of data when the hydrogen gas is actually filled at the hydrogen station <NUM>. Therefore, a conventional margin is not included in the correlation. In the example of <FIG>, a graph in which a plotted relation is approximated by a cubic polynomial is shown.

<FIG> is a diagram illustrating a coefficient table of a cubic polynomial when the correlation between the temperature increase change of the fuel tank and the filling speed is approximated by the cubic polynomial in the embodiment <NUM>. In <FIG>, values of coefficients A, B, C, and D of the cubic polynomial described in <FIG> are defined for each hydrogen gas supply temperature. In the example of <FIG>, a case where the coefficients A, B, C, and D of the cubic polynomial are defined for hydrogen gas supply temperatures of -<NUM>, -<NUM>, -<NUM>, -<NUM>, -<NUM>, - <NUM>, and -<NUM> is shown. Hydrogen gas supply temperatures that are not shown in the correlation equation of <FIG> may be obtained by linear interpolation. Further, when hydrogen gas supply temperatures at the time of actual calculation are not defined, linearly interpolated values may be used.

In <FIG>, the relation expression between the temperature increase change of the fuel tank <NUM> and the filling speed is shown, but the relation may be defined as a relation table instead of the coefficient table. The relation table may also be created for each combination of the initial pressure Pa of the fuel tank <NUM> and the outside air temperature T' and for each hydrogen gas supply temperature.

As the filling speed calculation step (S114), the filling speed calculation unit <NUM> calculates the filling speed M of the hydrogen gas that depends on the difference ΔT. The filling speed M is calculated by using the above-described relation expression or relation table between the temperature increase change of the tank depending on the supply temperature of the hydrogen gas supplied via the dispenser <NUM> and the filling speed. Specifically, first, a coefficient table or a relation table of a relation expression corresponding to the initial pressure Pa of the fuel tank <NUM>, the outside air temperature T', and the preset hydrogen gas supply temperature T" is read from the storage device <NUM>. Since the refrigerant is not supplied from the refrigerator <NUM> to the cooler <NUM> before the start of filling, the hydrogen gas is not always sufficiently cooled. Therefore, the initial value T" of the hydrogen gas supply temperature may be preset. For example, the initial value T" = -<NUM> is set. When the circulation of the refrigerant is started, the hydrogen gas is cooled in a short period. For example, it is cooled in several tens of seconds. For this reason, until then, a temporary filling speed may be calculated with the initial value T". Therefore, the filling speed calculation unit <NUM> calculates the filling speed M corresponding to the calculated difference ΔT by referring to the coefficient table or the relation table of the read relation expression. The calculated filling speed M is output to the system control unit <NUM>.

As the hydrogen filling step (S116), the hydrogen gas is filled into the fuel tank <NUM> at the calculated filling speed M from the multi-stage accumulator <NUM> (accumulator) in which the hydrogen gas has been accumulated via the dispenser <NUM>. In other words, the dispenser <NUM> fills the fuel tank <NUM> with the hydrogen gas at the calculated filling speed M from the multi-stage accumulator <NUM> (accumulator).

<FIG> is a diagram illustrating a filling method in a case of performing differential pressure filling of the hydrogen fuel by using the multi-stage accumulator in the embodiment <NUM>. In <FIG>, a vertical axis indicates a pressure and a horizontal axis indicates a time. In the case of performing the differential pressure filling of the hydrogen fuel on the FCV <NUM>, generally, the hydrogen fuel is accumulated in the accumulators <NUM>, <NUM>, and <NUM> of the multi-stage accumulator <NUM> in advance at the same pressure P0 (for example, <NUM> MPa). On the other hand, the pressure of the fuel tank <NUM> of the FCV <NUM> that has arrived at the hydrogen station <NUM> becomes a pressure Pa. A case where filling starts for the fuel tank <NUM> of the FCV <NUM> from the above state will be described.

First, the filling starts from the 1st bank, for example, the accumulator <NUM> to the fuel tank <NUM>. Specifically, the following operation is performed. Under the control of the system control unit <NUM>, the supply control unit <NUM> controls the supply unit <NUM>, and supplies the hydrogen fuel from the accumulator <NUM> to the fuel tank <NUM> of the FCV <NUM>. Specifically, the system control unit <NUM> controls the dispenser control unit <NUM> and the valve control unit <NUM>. The dispenser control unit <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 the opening of the flow rate adjustment valve in the dispenser <NUM> so that a filling speed becomes the calculated filling speed M. Next, the control circuit <NUM> opens the shut-off valves <NUM> and <NUM> in the dispenser <NUM>. Then, the valve control unit <NUM> outputs a control signal to the valves <NUM>, <NUM>, and <NUM> via the communication control circuit <NUM>, and controls opening/closing of each valve. Specifically, the valve <NUM> is opened and the valves <NUM> and <NUM> are kept closed. As a result, the hydrogen fuel 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 fuel accumulated in the accumulator <NUM> moves to the side of the fuel tank <NUM> at the adjusted filling speed, 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, at a point of time when a pressure falls outside a use lower limit pressure of the 1st bank and a time T1 elapses from the start of filling, an accumulator to be used is switched from the accumulator <NUM> to the 2nd bank, for example, the accumulator <NUM>. Specifically, the valve control unit <NUM> outputs a control signal to the valves <NUM>, <NUM>, and <NUM> via the communication control circuit <NUM>, and controls opening/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 fuel accumulated in the accumulator <NUM> moves to the side of the fuel tank <NUM> at the same adjusted filling speed, 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, at a point of time when a pressure falls outside a use lower limit pressure of the 2nd bank and a time T2 elapses from the start of filling, an accumulator to be used is switched from the accumulator <NUM> to the 3rd bank, for example, the accumulator <NUM>. Specifically, the valve control unit <NUM> outputs a control signal to the valves <NUM>, <NUM>, and <NUM> via the communication control circuit <NUM>, and controls opening/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 3rd bank, for example, the accumulator <NUM> and the fuel tank <NUM>, the hydrogen fuel accumulated in the accumulator <NUM> moves to the side of the fuel tank <NUM> at the adjusted filling speed, 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, filling is performed until the pressure of the fuel tank <NUM> becomes the calculated final pressure PF (for example, <NUM> to <NUM> MPa) by the accumulator <NUM> to be the 3rd bank.

As described above, the fuel tank <NUM> is filled with the hydrogen gas in order from the 1st bank. As long as the hydrogen gas is filled at the calculated filling speed M, the temperature of the fuel tank <NUM> increases only to the maximum temperature Tmax even if it increases from the temperature (initial temperature) Ti of the fuel tank <NUM>. In other words, the temperature of the fuel tank <NUM> does not exceed the maximum temperature Tmax as long as the hydrogen gas is filled at the calculated filling speed M. However, such a relation holds unless the hydrogen gas supply temperature changes. For the outside air temperature, a change during a filling period of about several minutes may be regarded as an error level. Therefore, the filling speed M is reviewed on a regular basis.

As the determination step (S118), the determination unit <NUM> determines whether the filling has been completed. Specifically, the determination unit <NUM> determines whether the pressure in the fuel tank <NUM> has reached the calculated final pressure PF each time the time set in the timer <NUM> has elapsed. When the filling has been completed, the process proceeds to the refrigerator circulation stop step (S122) and the pressure recovery step (S124). When the filling has not been completed yet, the process proceeds to the hydrogen supply temperature input step (S120). The time set in the timer <NUM> is set to several tens of seconds (for example, <NUM> seconds) for the first filling immediately after the start of filling, and is set to several seconds (for example, <NUM> seconds) for the second and subsequent fillings. In the embodiment <NUM>, since the refrigerant is circulated from the refrigerator <NUM> to the cooler <NUM> each time the hydrogen gas is filled, the cooling of the hydrogen gas at the start of filling may be insufficient. Therefore, the time in the first filling is preferably set longer than the times in the second and subsequent fillings by considering a time required for cooling the hydrogen gas by the cooler <NUM>.

As the hydrogen supply temperature input step (S120), the filling speed calculation unit <NUM> inputs the present hydrogen supply temperature. Specifically, the latest temperature measured by the thermometer <NUM> stored in the storage device <NUM> is input as the latest hydrogen supply temperature. Then, the process returns to the filling speed calculation step (S114), and the steps from the filling speed calculation step (S114) to the hydrogen supply temperature input step (S120) are repeated until the filling is completed.

In the filling speed calculation step (S114), the filling speed calculation unit <NUM> reads, from the storage device <NUM>, a coefficient table or a relation table of a relation expression corresponding to the latest hydrogen supply temperature, the measured outside air temperature T', and the obtained initial pressure Pa of the fuel tank <NUM>. Then, the filling speed calculation unit <NUM> refers to the read coefficient table or relation table of the relation expression, and recalculates the filling speed M corresponding to the calculated difference ΔT. Here, only the hydrogen supply temperature is changed, and the other parameters are used without being changed. Then, the calculated filling speed M is output to the system control unit <NUM>. Then, each time the filling speed M is calculated, the opening of the flow rate adjustment valve <NUM> is readjusted so that a filling speed becomes the recalculated filling speed M. Then, each time the filling speed M is calculated, the hydrogen gas filling operation is continued at the readjusted filling speed M.

As the refrigerator circulation stop and pressure recovery continuation step (S122), when the filling is completed, the refrigerator control unit <NUM> controls the refrigerator <NUM> via the communication control circuit <NUM>, and stops the circulation pump of the refrigerator <NUM>. In this way, the circulation of the refrigerant between the refrigerator <NUM> and the cooler <NUM> is stopped. As a result, the cooling of the hydrogen gas by the cooler <NUM> in the dispenser <NUM> is stopped or the cooling speed is reduced. In the embodiment <NUM>, since the filling speed M corresponding to the actual temperature difference ΔT depending on the actual hydrogen supply temperature, the actual outside air temperature, and the actual initial pressure is used, it is possible to cope with the change in the hydrogen supply temperature. For this reason, it is possible to eliminate the need to cool the hydrogen gas excessively by the cooler <NUM> constantly. Therefore, the circulation pump that is constantly driven by the constant circulation in the past can be stopped during a period in which the hydrogen gas is not filled. As a result, it is possible to reduce electric power for driving the circulation pump, which has occurred during the period in which the hydrogen gas is not filled.

In the above-described example, cooling of the hydrogen gas is started by the cooler <NUM> in the dispenser <NUM> when the filling of the hydrogen gas into the fuel tank <NUM> is started, and the circulation of the refrigerant is stopped when the filling of the hydrogen gas into the fuel tank <NUM> is completed. However, the present invention is not limited thereto. The circulation amount of the refrigerant to the cooler <NUM> may be increased when the filling of the hydrogen gas into the fuel tank <NUM> is started, and the circulation amount of the refrigerant may be reduced when the filling of the hydrogen gas into the fuel tank <NUM> is completed. Even with such a configuration, the electric power for driving the circulation pump can be reduced.

Further, the pressure recovery mechanism <NUM> recovers the pressure of each of the accumulators <NUM>, <NUM>, and <NUM>. The compressor <NUM> and the valves <NUM>, <NUM>, and <NUM> configure the pressure recovery mechanism <NUM>. First, the system control unit <NUM> selects a supply source of the hydrogen fuel to be connected to the suction side of the compressor <NUM> from the curdle, the intermediate accumulator, the hydrogen trailer, or the hydrogen production apparatus (not shown). Then, under the control of the system control unit <NUM>, the pressure recovery control unit <NUM> controls the pressure recovery mechanism <NUM>, and recovers the pressure of each of the accumulators <NUM>, <NUM>, and <NUM>. Specifically, the following operation is performed. In the accumulator of each bank used for filling the fuel tank <NUM> of the FCV <NUM>, the pressure may also be recovered during filling. However, since there is not enough time to recover the pressure to a prescribed pressure, the pressure should be recovered after 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 control unit <NUM> opens the valve <NUM> from a state where the valves <NUM>, <NUM>, and <NUM> are closed.

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

Next, the valve control unit <NUM> closes the valve <NUM>, and opens the valve <NUM> instead.

Then, the compressor control unit <NUM> drives the compressor <NUM>, sends the hydrogen fuel of the low pressure (for example, <NUM> MPa) while compressing the hydrogen fuel, and fills the accumulator <NUM> with the hydrogen fuel until the pressure of the accumulator <NUM> becomes the predetermined pressure P0 (for example, <NUM> MPa), thereby recovering the pressure of the accumulator <NUM>.

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

As described above, according to the embodiment <NUM>, when the hydrogen gas is filled, the hydrogen gas can be filled at the filling speed M where the extra margin is eliminated Therefore, a filling time can be shortened. Further, the circulation pump is stopped during the period when the hydrogen gas is not filled. As a result, it is possible to reduce electric power for driving the circulation pump, which has occurred during the period in which the hydrogen gas is not filled.

The embodiment has been described with reference to the specific examples. However, the present invention is not limited to these specific examples. For example, in the above-described examples, the case where the multi-stage accumulator <NUM> including the three accumulators <NUM>, <NUM>, and <NUM> is used to fill one FCV with the hydrogen fuel has been described. However, the present invention is not limited thereto. According to the volumes of the accumulators <NUM>, <NUM>, and <NUM> and the like, more accumulators may be used for filling of one FCV. Alternatively, two accumulators may be used for filling of one FCV.

Further, descriptions of parts and the like that are not directly necessary for explanation of the present invention, such as the device configuration and the control method, are omitted. However, the necessary device configuration and control method can be appropriately selected and used, in any case, without departing from the scope of the appended claims.

In addition, all hydrogen gas filling methods and hydrogen gas filling devices, which include the elements of the present invention and are capable of being appropriately changed in design by those skilled in the art, are included in the scope of the present invention, without departing from the scope of the appended claims.

Claim 1:
A hydrogen gas filling method comprising:
receiving, from a vehicle (<NUM>) equipped with a tank (<NUM>) to be filled with hydrogen gas and powered by the hydrogen gas, a temperature of the tank (<NUM>) before a start of filling;
calculating a difference between a present maximum temperature and the temperature of the tank (<NUM>);
calculating a filling speed of the hydrogen gas depending on the difference; and
filling the hydrogen gas from an accumulator (<NUM>, <NUM>, <NUM>, <NUM>) in which the hydrogen gas is accumulated into the tank (<NUM>) at the calculated filling speed via a measuring machine (<NUM>),
wherein the filling speed is calculated by using a relation expression (<NUM>) or a relation table (<NUM>) between the difference and the filling speed, characterised in that the relation expression and the relation table depend on a supply temperature of the hydrogen gas supplied via the measuring machine (<NUM>).