Gas filling method

Abstract

To provide a gas charging method which is a simple method using the charging control of a hydraulic station without arranging a particular mechanism at a tank, can suppress the occurrence of a temperature separation in the tank, can quickly finish the charging of a gas, and can charge the gas at high performance and high efficiency.SOLUTION: A gas charging method for supplying a gas into a tank from a pressure accumulator via piping, and charging the gas into the tank includes: a step for setting temperature separation pressure Ps being pressure at which a temperature separation occurs during the charging of the gas in the tank; a temperature separation pressure detection step for detecting whether or not the pressure in the tank reaches the temperature separation pressure during the charging of the gas; and a boost rate raising step for raising a boost rate of the tank, and charging the gas into the tank after the pressure reaches the temperature separation pressure.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a gas filling method for filling a tank with fuel gas (gas) from a gas pressure accumulator via a pipe. [Background technology]

[0002] In recent years, research and development into fuel cells (FCs) has been conducted to contribute to energy efficiency, ensuring that more people have access to affordable, reliable, sustainable, and advanced energy.

[0003] For example, a fuel cell vehicle is equipped with the fuel cell, a tank for storing fuel gas, and a motor. The fuel cell generates electricity through an electrochemical reaction between the fuel gas supplied from the tank and an oxidizing gas (air). The fuel cell vehicle runs by driving the motor using the electricity generated by the fuel cell.

[0004] The tank mounted on the fuel cell vehicle is filled with gas (hydrogen gas) via piping (including hoses) at a filling station (hydrogen station). The hydrogen station is equipped with a pressure accumulator for high-pressure gas.

[0005] "Compressed hydrogen filling technical standards" such as JPEC-S0003 (Non-Patent Document 1) or SAEJ2601 are applied to the control of filling fuel gas (compressed hydrogen) into the fuel cell vehicles and the like at the hydrogen stations.

[0006] The "Technical Standards for Compressed Hydrogen Refueling" require simulations of factors such as the hydrogen filling speed (pressure increase rate), and the results are compiled into maps and tables for use in filling control. To improve calculation speed, this simulation uses a calculation model that assumes a uniform gas temperature inside the tank. At the start of filling, the tank's internal temperature is generally uniform because the inflowing gas ejects and stirs the interior. However, as filling progresses and the tank's internal pressure increases, the volumetric flow rate of the ejected gas decreases. This results in insufficient stirring inside the tank, leading to temperature unevenness. This temperature unevenness (temperature separation) is particularly likely to occur when the tank is large, the outside air temperature is high, and the filling time is long. Specifically, as shown in Figures 10A and 10B, the gas temperature rises in the upper, farthest area (dark area) from the tank's gas supply port. In this case, the simulated temperature and the actual internal tank temperature do not match. Furthermore, localized increases in gas temperature lead to variations in the measured tank temperature, making it difficult to reliably detect the tank temperature. Furthermore, if a high tank temperature that temporarily exceeds a predetermined temperature is detected, a safety device may be activated and the filling operation may be stopped.

[0007] In this regard, the high-pressure gas storage system in Patent Document 1 is equipped with a gas guide member that can change the injection direction of the fuel gas inside the high-pressure gas container when filling the high-pressure gas container with fuel gas, and the injection direction of the fuel gas is changed by driving this gas guide member. This makes it possible to direct the injection direction of the fuel gas toward a part of the high-pressure gas container that easily dissipates heat depending on the temperature and pressure conditions of the high-pressure gas container, thereby suppressing the temperature rise inside the high-pressure gas container. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Japanese Patent Application Laid-Open No. 2007-298051 Summary of the Invention [Problem to be solved by the invention]

[0009] However, if a gas guide member capable of changing the injection direction of fuel gas is provided inside a high-pressure gas container (tank), the structure of the high-pressure gas container becomes complex, the number of parts increases, leading to higher costs, and since the gas guide member has moving parts, there are problems such as reduced reliability.

[0010] The present invention aims to solve the above-mentioned problems. [Means for solving the problem]

[0011] A gas filling method according to one aspect of the present invention is a gas filling method in which a tank and a gas pressure accumulator are connected by piping, gas is supplied from the accumulator to the tank via the piping, and the tank is filled with gas, the method comprising the steps of: a step of setting a temperature separation pressure, which is the gas pressure at which temperature separation occurs while the tank is being filled with gas; a temperature separation pressure detection step of detecting whether the pressure inside the tank has reached the temperature separation pressure while the gas is being filled with gas; and a pressure increase rate increase step of increasing the tank pressure increase rate after the temperature separation pressure has been reached, thereby filling the tank with gas. [Effects of the Invention]

[0012] According to this invention, without installing any special mechanism in the tank, a simple method using hydrogen station filling control can be used to suppress the occurrence of temperature separation within the tank and complete gas filling in a short period of time, thereby achieving high-performance, highly efficient gas filling. [Brief explanation of the drawings]

[0013] [Figure 1] FIG. 1 is a configuration diagram of a hydrogen filling system to which a gas filling method according to an embodiment is applied. [Figure 2] FIG. 2 is a block diagram showing the configuration of the dispenser ECU. [Figure 3] FIG. 3 is a diagram showing the change over time in tank pressure according to the embodiment. [Figure 4]FIG. 4 is a flowchart illustrating the operation of a hydrogen filling system to which the gas filling method according to the embodiment is applied. [Figure 5] FIG. 5 is a diagram showing the boost rate of the first modification. [Figure 6] FIG. 6 is a flowchart illustrating the operation of a hydrogen filling system to which the gas filling method according to the first modification is applied. [Figure 7] FIG. 7 is a diagram showing the boost rate of the second modification. [Figure 8] FIG. 8 is a flowchart illustrating the operation of a hydrogen filling system to which the gas filling method according to the second modification is applied. [Figure 9] FIG. 9 is a subroutine in a flowchart of a hydrogen filling system to which the gas filling method according to the second modification is applied. [Figure 10] Fig. 10B is a schematic cross-sectional view showing the temperature distribution of gas in a tank in the prior art, and Fig. 10A is a cross-sectional view taken along line AA in Fig. 10B. DETAILED DESCRIPTION OF THE INVENTION

[0014] [Hydrogen filling system configuration] FIG. 1 shows the configuration of a hydrogen filling system 10 according to an embodiment to which a gas filling method according to an embodiment is applied.

[0015] The hydrogen filling system 10 is made up of a hydrogen station 14, which is a filling station (filling stand), shown on the left side of the two-dot chain line, and a fuel cell vehicle (vehicle) 16 shown on the right side of the two-dot chain line.

[0016] The hydrogen station 14 has a pressure accumulator 20 that is a supply source of hydrogen gas (gas) that is a fuel gas.

[0017] The vehicle 16 is equipped with a hydrogen tank (tank) 50 that is filled with gas supplied from the pressure accumulator 20 .

[0018] The vehicle 16 is equipped with a tank 50 for storing the filled gas, as well as a fuel cell (not shown) and a motor (not shown) for driving the vehicle.

[0019] The fuel cell generates electricity through an electrochemical reaction between fuel gas supplied from a tank 50 and oxidant gas (air) supplied from a compressor (not shown).

[0020] The vehicle 16 is a fuel cell vehicle that runs by driving the motor using electricity generated by the fuel cell.

[0021] Fuel cell vehicles include relatively small passenger cars as well as larger vehicles such as buses and trucks.

[0022] A fuel cell vehicle is a vehicle that travels on land and includes a tank 50 for storing gas and the fuel cell.

[0023] The mobile body to which the present invention is applicable is not limited to a mobile body that travels on the ground, but also includes an airplane, a ship, a submarine, and the like.

[0024] As shown in FIG. 1, the hydrogen station 14 includes a dispenser ECU (Electronic Control Unit) 22 , and the vehicle 16 includes a communication ECU 52 .

[0025] In FIG. 1, the communication ECU 52 and components related to the communication ECU 52, which are depicted by a broken line, are not necessary for carrying out (using) the gas filling method according to the embodiment.

[0026] The dispenser ECU 22 and the communication ECU 52 are control devices, and are configured by a computer having one or more processors (CPUs), memories (storage devices), timers (timers), counters (counters), input / output interfaces, and electronic circuits.

[0027] The one or more processors (CPUs) execute the programs stored in the memory, which stores not only the programs but also data such as acquired physical quantities and various control maps referenced by the data.

[0028] The processor (CPU) executes calculations (various functions) according to the program based on the acquired physical quantities and the like, and refers to the control map as necessary.

[0029] In FIG. 1, the vehicle 16 includes a vehicle pipe (pipe) 56 extending from the tank 50 to the receptacle 54, and a communication device 58, such as an infrared communication device, for transmitting and receiving a data signal Dt to the hydrogen station 14.

[0030] The vehicle piping 56 connecting the tank 50 and the receptacle 54 is provided with a dust filter 60 and a check valve 62 located near the receptacle 54 to prevent gas from flowing back from the tank 50 to the receptacle 54.

[0031] An in-tank temperature sensor 64 is provided inside the tank 50, and a pressure sensor 66 is provided in the vehicle piping 56 near the tank 50.

[0032] The communication ECU 52 acquires the tank temperature Tt detected by the tank temperature sensor 64 and the pressure (tank pressure) Pt inside the tank 50 detected by the pressure sensor 66, and generates a data signal Dt.

[0033] The generated data signal Dt is sent to the dispenser ECU 22 via the communication device 58 and the communication device 38 provided in the hydrogen station 14 .

[0034] The communication device 38 provided in the hydrogen station 14 is integrally attached to the nozzle 48 .

[0035] When the nozzle 48 of the hydrogen station 14 is connected to the receptacle 54 of the vehicle 16, the communication device 38 faces a communication device 58 provided in the vehicle 16. This enables the communication devices 38 and 58 to send and receive data signals Dt and the like wirelessly via infrared or other means.

[0036] The hydrogen station 14 has a pressure accumulator 20 that stores high-pressure hydrogen gas to be supplied to a tank 50 of the vehicle 16 .

[0037] The pressure accumulator 20 is provided with a shutoff valve 24. A station pipe 46 extending from the shutoff valve 24 to a nozzle 48 is connected between the shutoff valve 24 and the nozzle 48. High-pressure hydrogen gas is supplied to the pressure accumulator 20 from a compressor (not shown). The high-pressure hydrogen gas may be supplied directly from the compressor to the vehicle 16. Alternatively, high-pressure hydrogen gas may be obtained by directly compressing and heating liquid hydrogen.

[0038] The accumulator 20 and the tank 50 are connected (communicated) by a pipe 100 consisting of the station pipe 46 and the vehicle pipe 56 .

[0039] The station piping (piping) 46 is provided with a mass flow sensor (MFM: Mass Flow Meter, flow rate sensor) 26, a flow rate adjustment valve 28, a precooler (Pcool: Pre Cooler) 30, and a breakaway (BA: Break Away) 32 from the shutoff valve 24 toward the nozzle 48. In the station piping 46, the section between the breakaway 32 and the nozzle 48 is configured as a flexible hose.

[0040] A pressure sensor 34 and a temperature sensor 36 are provided in the station piping 46 between the precooler 30 and the breakaway 32 .

[0041] The pressure sensor 34 detects the gas pressure in the pressure accumulator 20 (hydrogen station 14) when the shutoff valve 24 is open as a dispenser pressure (gas pressure) Pd. The temperature sensor 36 detects the temperature of the gas supplied from the pressure accumulator 20 as a dispenser temperature (gas temperature) Td.

[0042] The flow rate sensor 26 detects the mass flow rate (flow rate) m of the gas flowing through the pipe 100 .

[0043] The dispenser pressure Pd, the dispenser temperature Td, and the flow rate m detected by the pressure sensor 34, the temperature sensor 36, and the flow rate sensor 26, respectively, are acquired by the dispenser ECU 22 as physical quantities.

[0044] The shutoff valve 24 opens and closes in response to an opening / closing signal Soc output from the dispenser ECU 22. The shutoff valve 24 transitions the valve from an open state to a closed state in response to the opening / closing signal Soc that is a closing signal, and maintains the closed state. The shutoff valve 24 transitions the valve from a closed state to an open state in response to the opening / closing signal Soc that is an opening signal, and maintains the open state.

[0045] The flow rate adjustment valve 28 can continuously adjust the valve opening degree by a flow rate adjustment signal Sas output from the dispenser ECU 22. In other words, the flow rate adjustment valve 28, whose valve opening degree is adjusted by the flow rate adjustment signal Sas, can continuously adjust the gas flow rate in the piping 100. The dispenser pressure Pd is controlled (adjusted) by adjusting the gas flow rate in the piping 100.

[0046] The precooler 30 cools the gas supplied from the accumulator 20 to the vehicle piping 56 at a position before it is filled into the tank 50, thereby suppressing a rise in the temperature of the gas inside the tank 50 and enabling rapid filling. The temperature of the cooled gas is the precool temperature.

[0047] The breakaway 32 is a safety device connected between the accumulator 20 and the nozzle 48. If the nozzle 48 is pulled by a strong external force, the breakaway 32 automatically closes its own valve to seal the flow path and cut off the gas flow.

[0048] The hydrogen station 14 is provided with an atmospheric temperature sensor (temperature sensor) 42 that detects the air temperature Ta. The air temperature Ta detected by the atmospheric temperature sensor 42 is acquired by the dispenser ECU 22.

[0049] [Dispenser ECU configuration] FIG. 2 is a block diagram showing the configuration of the dispenser ECU 22. As shown in FIG.

[0050] The dispenser ECU 22 includes a temperature detection unit 22a that receives the temperature detected by the temperature sensor 36, a pressure detection unit 22b that receives the pressure detected by the pressure sensor 34, a flow rate detection unit 22c that receives the flow rate m detected by the flow rate sensor 26, a flow rate control unit 22d that adjusts the valve opening of the flow rate adjustment valve 28 to adjust the pressure of the gas supplied from the nozzle 48 through the pipe 100, and a filling control unit 22e that sets a target pressure boost rate (pressure boost rate) Rptar. The filling control unit 22e controls the target pressure boost rate Rptar based on a target pressure boost rate map 22f that is prepared in advance. The target pressure boost rate map 22f includes a table of pressure boost rates corresponding to various outside temperatures and pre-cool temperatures.

[0051] [Gas filling method according to the embodiment] The hydrogen filling system 10 and the dispenser ECU 22 to which the gas filling method according to the embodiment is applied are basically configured as described above. The gas filling method according to the embodiment will now be described with reference to FIG.

[0052] The dispenser ECU 22 sets a target pressure increase rate (pressure increase rate) Rptar (pressure / time) which is the amount of change over time in the tank pressure (pressure of the gas in the tank 50) Pt. Note that, as the tank pressure Pt, any of the dispenser pressure Pd, the pressure obtained by subtracting the pressure loss in the piping 100 from the dispenser pressure Pd, or the actual tank pressure Pt detected by the pressure sensor 66 may be used. The target pressure increase rate Rptar can be set to a constant pressure increase rate (linear) or a non-linear pressure increase rate.

[0053] As shown in FIG. 3, the target pressure increase rate Rptar is expressed as a target pressure increase amount ΔPt_next, which is a target increase in the tank pressure Pt during a time step Δt, which is a small predetermined time, Rptar=(ΔPt_next) / Δt.

[0054] The dispenser ECU 22 adjusts the flow rate of the gas by the flow rate control unit 22d based on the target pressure increase rate map 22f so that the tank pressure Pt increases at the target pressure increase rate Rptar. That is, the dispenser ECU 22 fills the tank 50 with gas so that the tank pressure Pt increases at the target pressure increase rate Rptar.

[0055] In Figure 3, the change in tank pressure Pt over time according to the present invention is shown by a solid line. The tank pressure Pt, which increases according to the target pressure increase rate Rptar, has an upper limit pressure and a lower limit pressure, which are shown by dotted lines. The upper limit pressure is set so that the temperature of the tank 50 does not exceed a predetermined temperature while the tank 50 is being filled with gas. The upper limit pressure is set to a pressure approximately 5 to 10 MPa higher than the increasing tank pressure Pt. The lower limit pressure is set so that the temperature of the tank 50 does not fall below a predetermined temperature. If the temperature of the tank 50 falls below the predetermined temperature, the density of the gas increases, which could result in an excessive amount of gas being filled into the tank 50. The lower limit pressure is set to a pressure approximately 2 to 5 MPa lower than the increasing tank pressure Pt. The upper limit pressure and the lower limit pressure are specified by various standards.

[0056] The difference between the upper and lower limit pressures in the tank pressure Pt, which increases as the filling proceeds, is the pressure tolerance band. When the pressure increase rate is set, the pressure in the tank 50 is between the upper and lower limit pressures, and falls within the pressure tolerance band.

[0057] The tank 50 may have a temperature separation pressure (Ps). The temperature separation pressure Ps is the pressure at which the temperature of the gas becomes uneven and high temperature areas occur in some regions due to insufficient agitation of the gas inside the tank 50 when the gas is filled. In this case, a temperature distribution occurs between high temperature areas and low temperature areas inside the tank 50, i.e., temperature separation occurs. Normally, temperature separation is likely to occur when the pressure of the gas inside the tank 50 reaches 50 to 60 MPa or higher. Figures 10A and 10B schematically show how temperature separation occurs.

[0058] The temperature separation pressure Ps varies depending on the tank capacity, tank shape, pressure increase rate, outside air temperature, gas temperature, and shape of the blow-out nozzle, and is set in advance through experiments, simulations, etc. (step of setting the temperature separation pressure Ps). If the pressure increase rate is low, the volumetric flow rate of the blow-out gas decreases and the internal mixing force weakens, resulting in a lower temperature separation pressure Ps. Furthermore, if the outside air temperature is high and the temperature of the inflowing gas (pre-cooling temperature) is low, the difference in buoyancy of the gas within the tank 50 increases, resulting in a lower temperature separation pressure Ps. When the tank pressure Pt is relatively low, the volumetric flow rate of the gas supplied is large, so the inside of the tank 50 is sufficiently agitated, the temperature becomes uniform, and temperature separation is unlikely to occur. However, as filling progresses and the tank pressure Pt rises, the volumetric flow rate of the gas supplied decreases, the gas becomes less agitated, and temperature separation occurs.

[0059] As shown in FIG. 3 , in this invention, when the pressure of the gas in the tank 50 reaches near the temperature separation pressure Ps (at time Ts), the pressure increase rate is increased. In other words, the pressure increase rate (gradient: Rptar = (ΔPt_next') / Δt) after exceeding the temperature separation pressure Ps is greater than the pressure increase rate (gradient: Rptar = (ΔPt_next) / Δt) before exceeding the temperature separation pressure Ps. The pressure increase rate after exceeding the temperature separation pressure Ps is preferably set to be, for example, 50 to 100% greater than the pressure increase rate before exceeding the temperature separation pressure Ps. This increases the flow rate of gas flowing into the tank 50. This promotes agitation of the gas in the tank 50, effectively suppressing the occurrence of temperature separation. Furthermore, increasing the pressure increase rate can shorten the time required to fill the tank with gas. In this case, the gas pressure in the tank 50 is increased at a pressure increase rate that prevents the gas pressure from exceeding the upper limit pressure indicated by the dotted line in FIG. 3 .

[0060] The gas pressure in the tank 50 increases over time, and when it reaches the full-fill pressure Pend at time Tend, the tank is fully filled and filling is complete.

[0061] [Explanation of the gas filling method according to the embodiment using a flowchart] Next, the operation of the hydrogen filling system 10 according to the embodiment to which the gas filling method according to the embodiment is applied will be described in detail with reference to the flowchart shown in Figure 4. Unless otherwise specified, the program according to the flowchart is executed by the CPU of the dispenser ECU 22, but to avoid the cumbersomeness of describing this each time, it will be simply referred to as the CPU.

[0062] Before starting gas filling, the nozzle 48 of the hydrogen station 14 is fitted into the receptacle 54 of the vehicle 16 by an operator or the like, with the shutoff valve 24 of the accumulator 20 of the hydrogen station 14 closed.

[0063] When an operator or the like operates the filling start button (not shown) at the hydrogen station 14, the CPU performs a pre-shot filling, which fills a small amount of hydrogen, to equalize the pressure on the hydrogen station 14 side and the tank 50 of the vehicle 16. Furthermore, the CPU obtains the dispenser pressure Pd from the pressure sensor 34, which indicates (detects) the tank pressure Pt, and measures the initial tank pressure P0 of the vehicle 16 (Pd = Pt = P0).

[0064] In step S1, the CPU opens the shutoff valve 24 to allow gas to flow from the pressure accumulator 20 toward the tank 50.

[0065] In step S2, the CPU sets the pressure increase rate by referring to the target pressure increase rate map 22f by the filling control unit 22e shown in FIG. 2, and proceeds with filling of gas.

[0066] In step S3, the CPU checks whether the tank pressure Pt detected by the pressure detection unit 22b has reached the temperature separation pressure Ps (time: T=Ts) (temperature separation pressure detection process), and if the answer is affirmative (step S3: YES), the CPU proceeds to increasing the pressure increase rate in step S4.

[0067] In step S4, the CPU refers to the target pressure increase rate map 22f using the filling control unit 22e shown in Figure 2, and proceeds with filling of gas at a pressure increase rate that is higher than the pressure increase rate when the gas pressure in the tank 50 is lower than Ps (pressure increase rate increase process).

[0068] In step S5, the CPU checks whether the tank pressure Pt detected by the pressure detection unit 22b has reached the full-fill pressure Pend, and ends the current filling process when the tank pressure Pt has reached the full-fill pressure Pend (time: T=Tend).

[0069] [Gas filling method according to modified example 1] The gas filling method according to the first modification will be described with reference to FIG.

[0070] In the gas filling method according to the first modification, the pressure increase rate decreases when the pressure of the gas in the tank 50 reaches a pressure increase rate decrease start pressure Psa (time: T = Tsa), which is lower than the temperature separation pressure Psb (= Ps), before reaching a temperature separation pressure Psb (= Ps) (time: T = Tsb). In other words, the gradient of the line representing the pressure increase rate after exceeding the pressure increase rate decrease start pressure Psa is smaller than the gradient of the line representing the pressure increase rate before exceeding the pressure increase rate decrease start pressure Psa. As a result, as filling progresses, the pressure in the tank 50 approaches the lower limit pressure, and after the tank pressure Pt reaches the temperature separation pressure Psb, the pressure increase rate can be set higher within the pressure tolerance range. Note that the tank pressure Pt must always be maintained higher than the lower limit pressure. The pressure increase rate of the tank pressure Pt is controlled so that it remains within the pressure tolerance range.

[0071] The pressure increase rate decrease start pressure Psa is set to a pressure that is smaller than the temperature separation pressure Psb and is close to the temperature separation pressure Psb.

[0072] When the pressure of the gas in the tank 50 reaches near the temperature separation pressure Psb (time: T = Tsb), the pressure increase rate increases. In other words, the gradient of the line indicating the pressure increase rate after exceeding the temperature separation pressure Psb is greater than the gradient of the line indicating the pressure increase rate before exceeding the temperature separation pressure Psb. This increases the pressure of the gas in the tank 50, increases the flow rate of gas flowing into the tank 50, and improves the mixing effect. Therefore, the occurrence of temperature separation can be effectively suppressed. In this case, the pressure of the gas in the tank 50 increases so as not to exceed the upper limit pressure indicated by the dotted line in Figure 5.

[0073] The pressure of the gas in the tank 50 increases over time, and when it reaches the full-fill pressure Pend at time Tend, filling is complete.

[0074] [Explanation of the gas filling method according to the first modification using a flowchart] Next, the operation of the hydrogen filling system 10 to which the gas filling method according to the first modification is applied will be described in detail with reference to the flowchart shown in FIG.

[0075] In step S11, the CPU opens the shutoff valve 24 to allow gas to flow from the pressure accumulator 20 toward the tank 50.

[0076] In step S12, the CPU sets the pressure increase rate by using the filling control unit 22e shown in FIG. 2 with reference to the target pressure increase rate map 22f, and proceeds with filling of gas.

[0077] In step S13, the CPU checks whether the pressure of the gas in the tank 50 detected by the pressure detection unit 22b has reached the pressure increase rate decrease start pressure Psa (time: T=Tsa), and if the answer is affirmative (step S13: YES), the CPU proceeds to the process of decreasing the pressure increase rate in step S14.

[0078] In step S14, the CPU refers to the target pressure increase rate map 22f by the filling control unit 22e shown in Fig. 2 and proceeds with filling of gas at a pressure increase rate that is lower than the pressure increase rate when the gas pressure in the tank 50 is lower than Psa (pressure increase rate decreasing step). In this case, the pressure increase rate is set so that the gas pressure in the tank 50 always exceeds the lower limit pressure, and gas filling is proceeded.

[0079] In step S15, the CPU checks whether the pressure of the gas in the tank 50 detected by the pressure detection unit 22b has reached the temperature separation pressure Psb (time T=Tsb) (temperature separation pressure detection process), and if the answer is affirmative (step S15: YES), the CPU proceeds to increasing the pressure increase rate in step S16.

[0080] In step S16, the CPU refers to the target pressure increase rate map 22f using the filling control unit 22e shown in Figure 2, and proceeds with filling of gas at a pressure increase rate that is higher than the pressure increase rate when the gas pressure in the tank 50 is lower than Psb (pressure increase rate increase process).

[0081] In step S17, the CPU checks whether the dispenser pressure Pd has reached the full-fill pressure Pend of the tank 50, and ends the current filling process when the dispenser pressure Pd has reached the full-fill pressure Pend.

[0082] [Gas filling method according to modified example 2] A gas filling method according to the second modification will be described with reference to FIG.

[0083] In the gas filling method according to the second modification, when the pressure of the gas in the tank 50 reaches near the temperature separation pressure Ps (time: T=Ts), the pressure increase rate increases. Thereafter, when a predetermined pressure higher than the temperature separation pressure Ps is reached, the pressure increase rate decreases, as in the gas filling method shown in the first modification. Thereafter, the pressure increase rate repeatedly increases and decreases (pressure increase rate increase / decrease process), and when the pressure of the gas in the tank 50 reaches the full filling pressure Pend at the time Tend, filling is completed. The number of times the pressure increase rate is repeated is not particularly limited, and may be one or more times. Filling control is performed at a pressure increase rate that always keeps the pressure of the gas in the tank 50 within the pressure tolerance range described above.

[0084] [Explanation of the gas filling method according to the second modification using a flowchart] Next, the operation of the hydrogen filling system 10 to which the gas filling method according to the second modification is applied will be described in detail based on the flowcharts and subroutines shown in FIGS.

[0085] In step S21, the CPU opens the shutoff valve 24 to allow gas to flow from the pressure accumulator 20 toward the tank 50.

[0086] In step S22, the CPU sets the pressure increase rate by referring to the target pressure increase rate map 22f by the filling control unit 22e shown in FIG. 2, and proceeds with filling of gas.

[0087] In step S23, the CPU checks whether the pressure of the gas in the tank 50 detected by the pressure detection unit 22b has reached the temperature separation pressure Ps (temperature separation pressure detection process), and if the answer is affirmative (step S23: YES), the CPU proceeds with the processing in the multi-stage pressure increase rate subroutine S24.

[0088] FIG. 9 shows a detailed flowchart of the multi-stage boost rate subroutine S24. In step S24a, the CPU refers to the target pressure increase rate map 22f using the filling control unit 22e shown in Figure 2, and proceeds with filling of gas at a pressure increase rate that is higher than the pressure increase rate when the gas pressure in the tank 50 is lower than Ps (pressure increase rate increase process).

[0089] In step S24b, the CPU checks whether the pressure in the tank 50 detected by the pressure detection unit 22b has reached the temperature separation pressure Ps+ΔP1, and if the answer is affirmative (step S24b: YES), the CPU proceeds to step S24c.

[0090] ΔP1 is the pressure at which the gas pressure (Ps+ΔP1) in the tank 50 does not reach the upper limit pressure, and is set appropriately taking into consideration the size of the tank 50, the temperature distribution within the tank 50, the optimal filling time, etc.

[0091] In step S24c, the CPU checks whether the pressure of the tank 50 detected by the pressure detection unit 22b has reached the full-fill pressure (Pend), and if the answer is affirmative (step S24c: YES), the filling process is completed. On the other hand, if the answer is negative (step S24c: NO), the process proceeds to step S24d, where the pressure increase rate is decreased.

[0092] In step S24d, the CPU refers to the target pressure increase rate map 22f by the filling control unit 22e shown in Fig. 2, and proceeds with filling of gas at a pressure increase rate that is lower than the pressure increase rate when the gas pressure in the tank 50 is lower than Ps (pressure increase rate decreasing step). In this case, the pressure increase rate is set so that the gas pressure in the tank 50 always exceeds the lower limit pressure, and gas filling is proceeded.

[0093] In step S24e, the CPU checks whether the pressure in the tank 50 detected by the pressure detection unit 22b has reached the temperature separation pressure Ps+ΔP2, and if the answer is affirmative (step S24b: YES), the process proceeds to step S24f.

[0094] ΔP2 is a pressure at which the gas pressure (Ps+ΔP2) inside the tank 50 does not reach the upper limit pressure, and is set appropriately taking into consideration the size of the tank 50, the temperature distribution of the gas inside the tank 50, the optimum filling time, etc. Note that ΔP2 is a pressure greater than ΔP1.

[0095] In step S24f, the CPU adds predetermined increments of pressure α and pressure β to ΔP1 and ΔP2, respectively, and proceeds to S24g.

[0096] In step S24g, the CPU checks whether the pressure in the tank 50 detected by the pressure detection unit 22b has reached the full-fill pressure Pend, and if the answer is affirmative (step S24g: YES), the CPU exits the subroutine and completes the filling process. On the other hand, if the answer is negative (step S24g: NO), the CPU returns to the beginning of the multi-stage pressure boost rate subroutine S24 and proceeds to increasing the pressure boost rate in step S24a.

[0097] [Invention that can be understood from the embodiments] The invention that can be understood from the above-described embodiment will now be described. Note that for ease of understanding, some of the components are labeled with the same reference numerals as in the above-described embodiment, but the components are not limited to those labeled with those reference numerals.

[0098] (1) A gas filling method according to the present invention is a gas filling method in which a tank 50 and a gas pressure accumulator 20 are connected by a pipe 100, gas is supplied from the pressure accumulator to the tank 50 via the pipe 100, and the tank 50 is filled with gas, and the method includes the steps of: a step of setting a temperature separation pressure Ps, which is the pressure of the gas at which temperature separation occurs while the gas is being filled into the tank; a temperature separation pressure detection step (S3) of detecting whether the pressure inside the tank 50 has reached the temperature separation pressure while the gas is being filled; and a pressure increase rate increase step (S4) of increasing the pressure increase rate of the tank 50 after the temperature separation pressure has been reached, thereby filling the tank 50 with gas.

[0099] With this configuration, when the tank pressure Pt reaches the preset thermal separation pressure Ps and thermal separation begins to occur, the pressure increase rate is increased compared to before the thermal separation pressure Ps is reached, increasing the volumetric flow rate of the gas being supplied and promoting agitation of the gas within the tank 50. As a result, without providing a special mechanism for promoting agitation within the tank 50, a simple method using filling control at the hydrogen station 14 can suppress the occurrence of thermal separation within the tank 50, and can complete the filling of the tank 50 in a short time from the accumulator 20 via the piping 100, thereby achieving high-performance, highly efficient gas filling.

[0100] (2) In the gas filling method, the increase in the pressure increase rate may be performed within a pressure tolerance range.

[0101] As a result, the tank pressure Pt does not exceed the upper limit pressure of the pressure tolerance range, and does not fall below the lower limit pressure. Because the tank pressure Pt does not exceed the upper limit pressure, the tank temperature Tt does not exceed a predetermined temperature, and the tank 50 is not damaged. Because the tank pressure Pt does not fall below the lower limit pressure, it is possible to prevent the gas density from increasing and excessive gas from being filled.

[0102] (3) Furthermore, the gas filling method may include a pressure increase rate decreasing step (S14) in which the pressure increase rate is decreased within the pressure tolerance range and the gas is filled before the pressure in the tank 50 reaches the temperature separation pressure Ps.

[0103] This makes it possible to effectively utilize the pressure tolerance range and set the pressure increase rate even higher within the pressure tolerance range, thereby further promoting the mixing of gas.

[0104] (4) Furthermore, the gas filling method may include, after the pressure increase rate increasing step, a pressure increase rate increasing / decreasing step of filling the gas by repeatedly decreasing and increasing the pressure increase rate.

[0105] This makes it possible to further promote the agitation of the gas in the tank 50 by changing the pressure increase rate within the pressure tolerance range.

[0106] The present invention is not limited to the above disclosure, and various configurations can be adopted without departing from the gist of the present invention. [Explanation of symbols]

[0107] 10...Hydrogen filling system 14...Hydrogen station 16...Vehicle 20...Accumulator 22... Dispenser ECU 24... Shutoff valve 26...Flow sensor 28...Flow control valve 34...Pressure sensor 36...Temperature sensor 46...Station piping 48...Nozzle 50...Tank 54...Receptacle 56...Vehicle piping 100...Piping

Claims

1. A gas filling method comprising: connecting a tank and a gas pressure accumulator with a pipe; supplying gas from the pressure accumulator to the tank through the pipe; and filling the tank with gas, setting a temperature separation pressure, which is a pressure of the gas at which temperature separation occurs while the gas is being filled into the tank; a temperature separation pressure detection step of detecting whether the pressure in the tank reaches the temperature separation pressure while the gas is being filled; a pressure increase rate increasing step of increasing the pressure of the tank after the temperature separation pressure is reached and filling the tank with gas; A gas filling method comprising:

2. The gas filling method according to claim 1, The pressure increase rate is increased within the pressure tolerance range. Gas filling method.

3. The gas filling method according to claim 2, and a pressure increase rate decreasing step of decreasing the pressure increase rate within the pressure tolerance range and filling the tank before the pressure in the tank reaches a temperature separation pressure. Gas filling method.

4. The gas filling method according to any one of claims 1 to 3, After the pressure increase rate increasing step, a pressure increase rate increasing / decreasing step is included in which the pressure increase rate is repeatedly decreased and increased to fill the gas. Gas filling method.

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