JP5060118B2 - Fuel cell system - Google Patents

Description

  The present invention relates to a fuel cell system.

In recent years, a polymer electrolyte fuel cell (PEFC) that generates electricity by generating an electrochemical reaction by supplying hydrogen (fuel gas) to the anode and oxygen (oxidant gas) to the cathode, etc. The development of fuel cells is thriving. Such a fuel cell does not supply fuel gas and oxidant gas corresponding to the required power generation amount (for example, when the fuel cell is mounted on a fuel cell vehicle, the required acceleration based on the amount of depression of the accelerator pedal). Then, there is a risk of fuel gas and oxidant gas shortage in the fuel cell.
Therefore, in order to prevent such a gas shortage, a technique for controlling the flow rate of the fuel gas supplied to the fuel cell in accordance with the required power generation amount has been proposed (see Patent Document 1).

In addition, such a fuel cell has a unique temperature for generating power (preferable power generation temperature). For example, in the case of a polymer electrolyte fuel cell, the preferred power generation temperature is 70 to 80 ° C., which is a catalyst contained in the anode and cathode of an MEA (Membrane Electrode Assembly) that constitutes the fuel cell. Mainly depends on the type of Pt.
Therefore, for example, when starting power generation of a fuel cell from a low-temperature environment such as below freezing (less than 0 ° C.), a technology for temporarily increasing the amount of self-heat generated by power generation and starting the fuel cell while warming it up Has been proposed. Such activation is referred to as low temperature activation, and in particular, when starting from below freezing, it is referred to as below freezing.
JP 2003-151593 A

  However, even after starting at a low temperature and promoting the warm-up of the fuel cell as described above, the water may still be locally frozen on the surface of the MEA, and the area of the MEA that can effectively generate power ( The effective power generation area is sometimes small. In such a situation where the effective power generation area is small, when there is a large required power generation amount and the output of the fuel cell suddenly increases, the required power generation is simply performed regardless of the state of the fuel cell as in Patent Document 1. If the flow rate of the fuel gas is controlled according to the amount, the fuel cell may run out of fuel gas.

  Accordingly, the present invention provides a fuel cell system capable of preventing fuel gas shortage and appropriately generating power in the fuel cell by adjusting the flow rate of the fuel gas in accordance with the state of the fuel cell. And

As a means for solving the problem, the present invention includes a fuel cell fuel gas and oxidant gas to generate electric power by being supplied, promoting warm-up of the fuel cell when a predetermined condition is satisfied during startup and cold start order to the predetermined condition is a normal fuel cell system to start the case of non-establishment, the power generation state detecting means for detecting the output variation of the fuel cell as a power generation state of the fuel cell, the fuel A fuel gas flow rate adjusting means for adjusting the flow rate of the fuel gas supplied to the battery to increase or decrease stepwise, an effective power generation area estimating means for estimating an effective power generation area of the fuel cell, and a predetermined output change amount. and a switching threshold as a switching reference of when the fuel gas flow rate adjusting means increases or decreases the flow rate of the staged fuel gas, when cold start, the fuel gas flow rate adjusting means, the fuel gas As the amount increases, the switching threshold value is changed to a smaller value than when normally activated, and based on the effective power generation area estimated by the effective power generation area estimation means, the switching threshold value decreases as the effective power generation area decreases. A fuel characterized by further correcting the switching threshold after change, and increasing or decreasing the flow rate of the fuel gas based on the corrected switching threshold and the power generation state of the fuel cell detected by the power generation state detection means It is a battery system.
The present invention also includes a fuel cell that generates electricity by supplying fuel gas and oxidant gas, and when the predetermined condition is satisfied at the time of startup, the fuel cell is started at a low temperature to promote warm-up, and the predetermined A fuel cell system that normally starts when the condition is not satisfied, and a power generation state detection unit that detects a differential pressure between a target pressure of fuel gas supplied to the fuel cell and an actual pressure as a power generation state of the fuel cell A fuel gas flow rate adjusting means for adjusting the flow rate of the fuel gas supplied to the fuel cell to increase or decrease stepwise, an effective power generation area estimating means for estimating an effective power generation area of the fuel cell, and a predetermined differential pressure And the fuel gas flow rate adjusting means has a switching threshold value that serves as a switching reference when the flow rate of the fuel gas is increased or decreased in stages, and when the fuel gas flow rate adjusting means is started at a low temperature, the fuel gas flow rate adjusting means As the amount increases, the switching threshold value is changed to a smaller value than when normally activated, and based on the effective power generation area estimated by the effective power generation area estimation means, the switching threshold value decreases as the effective power generation area decreases. A fuel characterized by further correcting the switching threshold after change, and increasing or decreasing the flow rate of the fuel gas based on the corrected switching threshold and the power generation state of the fuel cell detected by the power generation state detection means It is a battery system.

  According to such a fuel cell system, when a predetermined condition is satisfied at the time of activation, the fuel cell system is activated at a low temperature in order to promote warm-up of the fuel cell. When the fuel cell system is thus started at a low temperature, that is, when experiencing a low temperature start, the fuel gas flow rate adjustment means sets a switching threshold value that is a switching reference so that the flow rate of the fuel gas increases, for example, Change to a smaller threshold.

Therefore, even if the low temperature startup is experienced, even if the power generation state is the same as the normal startup not experiencing the low temperature startup (for example, the output change amount of the fuel cell and the differential pressure on the anode side described later), the switching threshold value Is changed, the flow rate of the fuel gas supplied to the fuel cell increases. Therefore, even if the MEA (electrolyte membrane, etc.) that constitutes the fuel cell is still frozen locally, even if its effective power generation area is small, it is not frozen and the MEA that can generate electricity satisfactorily. The amount of fuel gas supplied to the part increases. Therefore, the fuel gas shortage is less likely to occur in the MEA portion where power can be generated well, and the fuel cell can generate power well.
In addition, when the fuel gas is insufficient, the electrolyte membrane may be deteriorated due to electrolytic corrosion (for example, electrolysis of the electrolyte membrane). However, since the fuel gas is hardly insufficient, the electrolyte membrane is prevented from being deteriorated, and the electrolyte membrane is prevented. Can extend the lifespan.
According to such a fuel cell system, the effective power generation area of the fuel cell can be estimated by the effective power generation area estimation means.
Then, the fuel gas flow rate adjusting means corrects the switching threshold based on the estimated effective power generation area. Specifically, when the effective power generation area is small, the switching threshold is corrected to a small threshold so that the flow rate of the fuel gas increases. On the other hand, when the effective power generation area is large, the switching threshold is set so that the flow rate of the fuel gas decreases. Correct to a large threshold. Therefore, fuel gas can be supplied to the fuel cell at an appropriate flow rate corresponding to the estimated effective power generation area.

Further, the present invention comprises a fuel cell fuel gas and oxidant gas to generate electric power by being supplied, and the cold start to accelerate the warm-up of the fuel cell when a predetermined condition is satisfied when starting the predetermined condition Is a fuel cell system that normally starts when the above is not established, a required power generation amount detecting means for detecting a required power generation amount required for the fuel cell, and a flow rate of fuel gas supplied to the fuel cell in a stepwise manner. Fuel gas flow rate adjusting means for adjusting to increase / decrease , effective power generation area estimating means for estimating the effective power generation area of the fuel cell, and a predetermined required power generation amount, wherein the fuel gas flow rate adjusting means is a stepwise fuel gas and a switching threshold that becomes the switching reference when increasing or decreasing the flow rate, when the low-temperature starting, the fuel gas flow rate adjusting means so that the flow rate of the fuel gas increases, smaller than when normally started Change to the switching threshold, and based on the effective power generation area estimated by the effective power generation area estimation means, further correct the switching threshold after the change so that the switching threshold decreases as the effective power generation area decreases, and switch after correction The fuel cell system is characterized in that the flow rate of the fuel gas is increased or decreased based on the threshold value and the required power generation amount detected by the required power generation amount detection means .

  According to such a fuel cell system, when the low temperature startup is experienced, even if there is the same required power generation amount as during normal startup that does not experience low temperature startup, the switching threshold is changed. The flow rate of the fuel gas supplied to is increased. Therefore, even if the effective power generation area of the MEA that constitutes the fuel cell is reduced, the amount of fuel gas supplied to the MEA part that can generate power well increases, and the fuel cell generates power according to the required power generation amount. It becomes possible to do.

  In addition, the fuel cell system is a system mounted on a mobile body, the mobile body moves based on the generated power of the fuel cell, and the required power generation amount is required for the mobile body. The fuel cell system is calculated based on a required acceleration.

  According to such a fuel cell system, the required power generation amount required for the fuel cell is calculated based on the required acceleration required for the moving body. Then, the flow rate of the fuel gas is adjusted based on the calculated required power generation amount. That is, it is possible to adjust the flow rate of the fuel gas based on the required acceleration required for the moving body, to suitably generate the fuel cell, and to accelerate the moving body.

  A circulation flow path for circulating the fuel gas by returning the discharged fuel gas discharged from the fuel cell to a fuel gas supply flow path through which the fuel gas supplied from the fuel gas source to the fuel cell flows; A nozzle for injecting a fuel gas from the fuel gas source; and a fuel gas from the fuel gas source and the circulation channel. An ejector that mixes with the discharged fuel gas, and the ejector includes an injection port adjustment mechanism that adjusts an injection cross-sectional area at the injection port of the nozzle, and the injection cut-off at the injection port of the nozzle by the injection port adjustment mechanism. The fuel cell system is characterized in that the flow rate of the fuel gas to the fuel cell is adjusted by adjusting the area.

According to such a fuel cell system, since the circulation channel and the ejector are provided, the fuel gas source (for example, a hydrogen tank) is provided in the ejector while returning the exhaust fuel gas discharged from the fuel cell to the fuel gas supply channel. The fuel gas from the fuel gas is injected from the nozzle, and the fuel gas from the injected fuel gas source and the exhaust fuel gas are mixed and supplied to the fuel cell.
Here, the temperature of the discharged fuel gas discharged from the fuel cell is generally higher than that of the fuel gas from the fuel gas source due to self-heating caused by the power generation of the fuel cell. Therefore, the temperature of the fuel gas supplied to the fuel cell can be increased by mixing the exhaust fuel gas having such a high temperature and the fuel gas from the fuel gas source with the ejector. Then, by supplying the fuel gas whose temperature has been increased to the fuel cell, the temperature decrease of the fuel cell can be suppressed. Therefore, even if the flow rate of the fuel gas to the fuel cell is increased, the temperature reduction of the fuel cell due to the fuel gas can be prevented.

  Further, the flow rate of the fuel gas from the fuel gas source to be injected is adjusted by the injection port adjustment mechanism of the ejector that constitutes the fuel gas flow rate adjusting means, by adjusting the injection cross-sectional area at the injection port of the nozzle that injects the fuel gas And the flow rate is adjusted. As described above, since the flow rate of the fuel gas is adjusted, the suction negative pressure generated based on the flow of the fuel gas is also adjusted, and the flow rate of the discharged fuel gas sucked by the ejector is also adjusted. In this way, by adjusting the injection cross-sectional area at the nozzle injection port by the injection port adjustment mechanism of the ejector, the fuel gas supplied to the fuel cell (the fuel gas from the fuel gas source and the exhaust fuel gas are reduced. The flow rate of the mixture) can be adjusted.

  In addition, when the injection port adjusting mechanism is configured to include a needle that is freely inserted and removably inserted into the nozzle injection port as in an embodiment described later, the needle is adjusted to a power generation state or a required power generation amount by a solenoid or the like. By correspondingly advancing and retreating instantaneously, the injection cross-sectional area at the nozzle outlet can be instantaneously adjusted. Therefore, according to such a configuration, the flow rate of the fuel gas from the fuel gas source injected from the nozzle injection port can be instantaneously adjusted in accordance with the power generation state or the required power generation amount. The flow rate of the fuel gas to the battery (a mixture of the fuel gas from the fuel gas source and the exhausted fuel gas) can be instantaneously adjusted.

As a result, when the fuel cell system is installed in a fuel cell vehicle, the driver suddenly depresses the accelerator pedal, and the required acceleration (required power generation amount) for the fuel cell vehicle, Even if the output (power generation state) suddenly increases, the needle is instantaneously advanced or retracted correspondingly, and the fuel gas flow rate can be instantaneously increased. Therefore, fuel gas shortage in the fuel cell can be prevented, the output (generated power) of the fuel cell can be increased, and the fuel cell vehicle can be accelerated.
Furthermore, such an ejector can be easily configured by adding a needle to the conventional ejector, and it is not necessary to provide other devices such as a flow rate adjusting valve, so that space can be saved.

  Further, the fuel cell temperature detecting means for detecting the temperature of the fuel cell is further provided, and the fuel gas flow rate adjusting means continues to change the switching threshold until the temperature of the fuel cell becomes equal to or higher than a predetermined temperature. This is a fuel cell system.

  According to such a fuel cell system, the change of the switching threshold is continued by the fuel gas flow rate adjusting means until the temperature of the fuel cell by the fuel cell temperature detecting means becomes equal to or higher than a predetermined temperature. In other words, when the temperature of the fuel cell becomes equal to or higher than the predetermined temperature, the change of the switching threshold for increasing the flow rate of the fuel gas is stopped, so that it is possible to suppress unnecessary fuel gas supply and consumption. .

  ADVANTAGE OF THE INVENTION According to this invention, fuel gas shortage can be prevented by adjusting the flow volume of fuel gas corresponding to the state of a fuel cell, and a fuel cell can be made to generate electric power suitably.

<< First Embodiment >>
Hereinafter, a first embodiment of the present invention will be described with reference to FIGS. 1 to 5 as appropriate.

≪Configuration of fuel cell system≫
A fuel cell system 1 according to the first embodiment shown in FIG. 1 is mounted on a fuel cell vehicle (mobile body) (not shown). The fuel cell system 1 includes a fuel cell 110, an anode system that supplies and discharges hydrogen (fuel gas and reaction gas) to and from an anode of the fuel cell 110, and air that contains oxygen to the cathode of the fuel cell 110 (oxidation). A cathode system that supplies and discharges agent gas and reaction gas), a power consumption system that is connected to an output terminal (not shown) of the fuel cell 110 and consumes the generated power of the fuel cell 110, an IG 151 (ignition), and an accelerator A pedal 152 and an ECU 160 (Electronic Control Unit) that electronically controls these pedals are mainly provided. The fuel cell 110 generates electric power according to the amount of depression of the accelerator pedal 152 by the driver, and the driving motor 141 is driven by the generated electric power, so that the fuel cell vehicle is driven.

<Fuel cell>
The fuel cell 110 (fuel cell stack) is a solid polymer fuel cell configured by stacking a plurality of single cells. The single cell includes an MEA (Membrane Electrode Assembly) in which both surfaces of an electrolyte membrane (solid polymer membrane) are sandwiched between an anode (fuel electrode) and a cathode (air electrode), and a pair of separators that sandwich the MEA. , Mainly. Each separator is formed with a groove for supplying hydrogen or air to the entire surface of the MEA constituting each single cell, a through-hole for introducing hydrogen and air to all the single cells, and the like. It functions as an anode channel 111 (fuel gas channel) and a cathode channel 112 (oxidant gas channel).

  Then, when hydrogen is supplied to each anode via the anode channel 111 and oxygen-containing air is supplied to each cathode via the cathode channel 112, the catalyst (Pt or the like) contained in the anode and cathode is used. An electrochemical reaction occurs, and a potential difference (OCV (Open Circuit Voltage), open circuit voltage) is generated in each single cell. Next, when there is a power generation request for the fuel cell 110 in which a potential difference has occurred in each single cell in this way and the current is taken out, the fuel cell 110 generates power.

  The separator is formed with a refrigerant channel 113 through which a refrigerant (radiator liquid) for appropriately cooling the fuel cell 110 flows. The refrigerant flows in the order of the pipe 113a, the refrigerant flow path 113, and the pipe 113b.

<Anode system>
The anode system mainly includes a hydrogen tank 121 (fuel gas source) in which hydrogen is stored, a shut-off valve 122, an ejector 10, a pressure sensor 123, and a purge valve 124.
The hydrogen tank 121 is connected to the inlet of the anode flow path 111 through the pipe 121a, the shutoff valve 122, the pipe 122a, the ejector 10, and the pipe 10a in this order. When the shutoff valve 122 is opened by the ECU 160, hydrogen is supplied to the anode flow path 111. The piping 122a is provided with a pressure reducing valve (not shown) so that hydrogen is depressurized to a predetermined pressure.

  The pressure sensor 123 is provided in the pipe 10a so that the pressure of hydrogen (gas) in the anode flow path 111 can be detected. The pressure sensor 123 is connected to the ECU 160, and the ECU 160 detects the pressure of hydrogen in the anode flow path 111.

A pipe 124a, a purge valve 124, and a pipe 124b are sequentially connected to the outlet of the anode channel 111. The middle of the pipe 124a is connected to the ejector 10 through the pipe 124c.
The purge valve 124 is an on-off valve such as a gate valve, and is normally closed. When the purge valve is closed in this way, the anode off-gas (exhaust fuel gas) containing unreacted hydrogen discharged from the anode flow path 111 is returned to the ejector 10 via the pipe 124c, and again, Supply to the fuel cell 110, that is, hydrogen circulates.
On the other hand, when impurities such as moisture in the anode off-gas increase, that is, when impurities accompanying the circulating hydrogen increase, the purge valve 124 is opened by the ECU 160, and the anode off-gas is discharged to the outside via the pipe 124b. It is supposed to be discharged.

  Here, in the first embodiment, the fuel gas supply channel through which hydrogen supplied from the hydrogen tank 121 (fuel gas source) to the fuel cell 110 flows is the piping 121a, the shutoff valve 122, the piping 122a, the ejector 10, and the piping 10a. It is configured with. And the circulation channel which circulates hydrogen is comprised by the piping 124c. Further, the ejector 10 is provided at the junction of the fuel gas supply channel and the circulation channel.

[Ejecta]
Next, the ejector 10 will be described in detail.
In the state where the purge valve 124 is closed, the ejector 10 generates negative pressure by injecting hydrogen from the hydrogen tank 121 through a nozzle 30 described later, and sucks anode off-gas via the pipe 124 c from the hydrogen tank 121. Is a device for mixing hydrogen and anode off-gas.

  As shown in FIGS. 2 and 3, such an ejector 10 moves freely on its axis in a base body 20, a nozzle 30 screwed to the base body 20, and a hollow portion 31 of the nozzle 30. The needle 40 loosely inserted into the injection port 32 of the nozzle 30, the diffuser 50 screwed to the base body 20 outside the nozzle 30, the casing 60 externally fitted to the diffuser 50, and screwed to the base body 20. And a solenoid part 70 having a solenoid 71.

  The needle 40 is urged toward the nozzle 30 by a compression coil spring 72 built in the solenoid unit 70. When the solenoid 71 is turned off, the base end portion 41 of the needle 40 functioning as a stopper abuts on the base body 20, and the needle 40 is arranged at the OFF position of the solenoid 71. When the needle 40 is in the OFF position in this manner, the tip 42 of the needle 40 protrudes from the injection port 32 of the nozzle 30 and the hydrogen injection cross-sectional area at the injection port 32 becomes small (the injection port of the nozzle 30: small). The flow rate (injection flow rate) of hydrogen from the hydrogen tank 121 injected by the nozzle 30 is designed to decrease (see FIG. 2).

  On the other hand, when the solenoid 71 is turned on by the ECU 160, the needle 40 moves backward with respect to the nozzle 30 and is arranged at the ON position of the solenoid 71. When the needle 40 is in the ON position as described above, the tip 42 of the needle 40 is separated from the injection port 32, the hydrogen injection cross-sectional area at the injection port 32 becomes large (the injection port of the nozzle 30: large), and hydrogen It is designed to increase the flow rate (injection flow rate) of hydrogen from the tank 121 (see FIG. 3).

  The diffuser 50 has a hydrogen channel 51 on the central axis thereof, and a diameter-reduced portion 52 in which the cross-sectional area of the substantially circular hydrogen channel 51 gradually decreases toward the downstream side, and the cross-sectional area is minimum. A throat portion 53, and a diameter-expanding portion 54 whose diameter is gradually increased. A plurality of (for example, four) anode off gas introduction holes 55 are formed in the reduced diameter portion 52 in the circumferential direction.

  When the purge valve 124 (see FIG. 1) is closed, hydrogen from the hydrogen tank 121 is injected from the injection port 32 through the hydrogen flow path 21 formed in the base 20 and the hollow portion 31 of the nozzle 30. When it is done, negative pressure is generated. Next, due to the negative pressure, the anode off-gas is supplied from the pipe 124c (see FIG. 1) to the anode off-gas introduction hole 61 of the casing 60, the ring-shaped distribution manifold space 62 formed between the diffuser 50 and the casing 60, a plurality of The hydrogen channel 51 is sucked through the anode off-gas introduction hole 55. Thereafter, in the hydrogen flow path 51 in the enlarged diameter portion 54, the injected hydrogen from the hydrogen tank 121 and the sucked anode off-gas are mixed and directed to the fuel cell 110.

  That is, in the first embodiment, the injection port adjustment mechanism that adjusts the injection cross-sectional area of the nozzle 30 includes the needle 40, the solenoid 71, and the compression coil spring 72. The ejector 10 having such an injection port adjusting mechanism constitutes a fuel gas flow rate adjusting means for adjusting the flow rate of hydrogen supplied to the fuel cell 110.

<Cathode system>
Returning to FIG. 1, the description will be continued.
The cathode system mainly includes a compressor 131 and a temperature sensor 132 (fuel cell temperature detection means).
The compressor 131 is connected to the inlet of the cathode channel 112 via a pipe 131a. When the compressor 131 is operated in accordance with a command from the ECU 160, air containing oxygen is pumped to the cathode channel 112. The pipe 131a is provided with a humidifier (not shown) so that air sent to the fuel cell 110 is appropriately humidified.

  A pipe 132 a is connected to the outlet of the cathode channel 112. And the cathode off gas discharged | emitted from the cathode flow path 112 is discharged | emitted outside via the piping 132a.

  The temperature sensor 132 is provided near the fuel cell 110 in the pipe 132a, and the temperature of the cathode off-gas discharged from the fuel cell 110 is determined based on the current temperature of the fuel cell 110 and the temperature of the fuel cell system 1 (hereinafter, system temperature). (Generally referred to as T11). The temperature sensor 132 is connected to the ECU 160, and the ECU 160 detects the current system temperature T11.

<Power consumption system>
The electric power consumption system mainly includes an electric traveling motor 141 for traveling a fuel cell vehicle, a VCU 142 (Voltage Control Unit), and an output detector 143. The traveling motor 141 includes the VCU 142 and the output detector 143. Are sequentially connected to an output terminal (not shown) of the fuel cell 110.
The travel motor 141 is an electric motor that causes the fuel cell vehicle to travel.
The VCU 142 is a unit that controls the output (generated power) of the fuel cell 110 in accordance with a command from the ECU 160, and includes a DC-DC chopper and the like. That is, when the ECU 160 appropriately controls the VCU 142 in response to the power generation request, current is extracted from the fuel cell 110 in response to the power generation request, and the fuel cell 110 generates power.
The output detector 143 is a device that detects an output current and an output voltage of the fuel cell 110, and includes an ammeter and a voltmeter, and the ammeter and the voltmeter are arranged at appropriate positions. The output detector 143 is connected to the ECU 160, and the ECU 160 detects the current output current and output voltage of the fuel cell 110.

<IG, accelerator pedal>
The IG 151 is a start switch for the fuel cell vehicle and the fuel cell system 1 and is provided around the driver's seat. Moreover, IG151 is connected with ECU160, and ECU160 detects the ON / OFF signal of IG151.

  The accelerator pedal 152 is a pedal that a driver steps on to accelerate the fuel cell vehicle, and is disposed at the foot of the driver's seat. The accelerator pedal 152 is connected to the ECU 160, and the ECU 160 detects the amount of depression of the accelerator pedal 152.

<ECU>
The ECU 160 is a control device that electronically controls the fuel cell system 1, and includes a CPU, a ROM, a RAM, various interfaces, an electronic circuit, and the like.
When the ECU 160 detects the ON signal of the IG 151, the ECU 160 is configured to open the shut-off valve 122, operate the compressor 131, and appropriately control the VCU 142 to start the power generation of the fuel cell 110.

Further, the ECU 160 has a function of starting the fuel cell system 1 at a low temperature or starting normally based on the system temperature T11 when the IG 151 is ON.
Further, the ECU 160 (power generation state detection means) is based on the output (current, voltage) of the fuel cell 110 detected by the output detector 143, and the output change amount (output current change amount (output current change amount ( A / s), output power variation (kW / s), etc.).

Further, the ECU 160 (fuel gas flow rate adjusting means) is based on the output change amount of the fuel cell 110 and the switching threshold value that serves as a switching reference for the hydrogen flow rate to the fuel cell 110 (position of the needle 40). Has a function of adjusting the flow rate of hydrogen supplied to (see FIG. 5). Specifically, the ECU 160 is set to turn on the solenoid 71 and increase the injection cross-sectional area at the injection port 32 of the nozzle 30 when the output change amount is equal to or greater than the switching threshold. On the other hand, when the output change amount is not equal to or greater than the switching threshold, the solenoid 71 is turned off and the injection cross-sectional area at the injection port 32 of the nozzle 30 is set to be small (see FIGS. 2, 3, and 5).
That is, in the first embodiment, the fuel gas flow rate adjusting means includes the nozzle 30, the needle 40, the solenoid 71, and the like that constitute the injection port adjusting mechanism, and the ECU 160.

  Further, ECU 160 corrects the switching threshold based on the function of changing the switching threshold in accordance with the presence or absence of experience of cold start (see arrow A1 in FIG. 5) and the effective power generation area of the MEA that constitutes fuel cell 110. (See arrow A2 in FIG. 5).

≪Operation of fuel cell system≫
Next, the operation of the fuel cell system 1 will be described together with the flow of a program (flow chart) set in the ECU 160 with reference mainly to FIG. When the IG 151 is turned on, the ECU 160 that detects this ON signal executes various processes, and as a result, the flowchart shown in FIG. 4 starts.

  In step S101, the ECU 160 detects the system temperature T11 when the IG 151 is ON via the temperature sensor 132.

  In step S102, ECU 160 determines whether or not it is necessary to start the fuel cell 110 at a low temperature in order to promote the warm-up of the fuel cell 110 based on the system temperature T11 when the IG 151 is ON and the low temperature start determination temperature T0 (for example, 0 ° C.). Determine whether. The low temperature start determination temperature T0 is a temperature at which the inside of the fuel cell 110 or the like may be frozen if the system temperature T11 is lower than the temperature, and is obtained by a preliminary test or the like and stored in the ECU 160. ing.

  When it is determined that the system temperature T11 is lower than the low temperature start determination temperature T0 and it is necessary to start at a low temperature (Yes in S102, when a predetermined condition is satisfied), the processing of the ECU 160 proceeds to step S105. On the other hand, when the system temperature T11 is not lower than the low temperature start determination temperature T0 and it is determined that the low temperature start is not necessary (S102, No, when the predetermined condition is not satisfied), the processing of the ECU 160 proceeds to step S103.

For convenience, the case of proceeding to step S103 will be described first.
In step S103, the ECU 160 supplies the fuel cell 110 with normal flow rates of hydrogen and air, and normally starts the fuel cell system 1.

After starting the fuel cell system 1 normally, in step S104, the ECU 160 operates the fuel cell system 1 normally. In this normal operation, the switching threshold value is not changed or corrected (see FIG. 5), the fixed switching threshold value set in advance, the output change amount of the fuel cell 110 (output current change amount (A / s), output power) Based on the amount of change (kW / s, etc.), the injection cross-sectional area at the injection port 32 of the nozzle 30 is controlled.
Subsequently, the process of the ECU 160 proceeds to the end, and the control at the time of starting the system is terminated.

Next, the case where it progresses to step S105 is demonstrated.
In step S105, the ECU 160 starts the fuel cell system 1 at a low temperature.
Here, the method for starting the fuel cell system 1 at a low temperature is not limited, but examples of the method for starting at a low temperature include (1) a larger amount of hydrogen and air than the fuel cell 110 during normal startup. There is a method of increasing the self-heating amount of the fuel cell 110 by controlling the VCU 142 so that the output power of the fuel cell 110 is increased while supplying the fuel cell 110. In addition, (2) there is a method of increasing the self-heating amount of the fuel cell 110 by reducing the hydrogen and air supplied to the fuel cell 110 after setting the output power of the fuel cell 110 to the same as that at the normal startup. .

  Thereafter, in step S106, the ECU 160 promotes the warm-up of the fuel cell 110 by the low temperature startup, but there is a possibility that the MEA (fuel cell 110) may not be able to generate power. Even if (specifically, the output increase amount) is small, the switching threshold value that is a reference for switching the hydrogen flow rate is changed to a small value so that the flow rate of hydrogen supplied to the MEA that can generate power normally increases (see FIG. 5, see arrow A1).

In step S <b> 107, ECU 160 estimates the effective power generation area of the MEA constituting fuel cell 110.
Here, the method for estimating the effective power generation area of the MEA is not particularly limited. For example, (1) the control pressure of hydrogen to the anode corresponding to the power generation request (the control pressure on the secondary side of the pressure reducing valve (not shown)) and the pressure Although the VCU 142 is controlled according to the required power generation amount based on the pressure difference from the actual pressure by the sensor 123 and hydrogen is consumed in the fuel cell 110, the actual pressure by the pressure sensor 123 is high and the pressure difference is If the size is large, there is a method for estimating that the MEA has a portion that cannot generate power.
In addition, (2) when the output current corresponding to the amount of depression of the accelerator pedal 152 and the output voltage (IV characteristic) are not detected by the output detector 143 even though the accelerator pedal 152 is depressed, the MEA There is a method to estimate that there is a part that cannot generate electricity.

In step S108, the ECU 160 corrects the switching threshold based on the effective power generation area estimated in step S107 (see arrow A2 in FIG. 5).
Specifically, when the estimated effective power generation area is smaller than the standard effective power generation area, which is the standard where there is no non-power-generating part, even if the actual output change (output increase) is small, power generation is effective. Change to a small switching threshold so that the flow rate of hydrogen supplied to possible MEAs increases. On the other hand, when the estimated effective power generation area is larger than the reference effective power generation area, the threshold value is changed to a large switching threshold so that the flow rate of hydrogen supplied to the MEA capable of generating power effectively decreases.

  In step S109, the ECU 160 via the output detector 143, the actual output change amount of the fuel cell 110 per unit time (output current change amount (A / s), output power change amount (kW / s), etc.). Is detected.

  In step S110, ECU 160 determines whether or not the amount of change in output detected in step S109 is greater than or equal to the change / correction switching threshold.

  If it is determined that the output change amount is equal to or greater than the switching threshold (S110 / Yes), the process proceeds to step S111, and the ECU 160 turns on the solenoid 71 of the ejector 10. Then, as shown in FIG. 3, the needle 40 moves backward with respect to the nozzle 30, and the injection cross-sectional area at the injection port 32 of the nozzle 30 increases. As a result, the hydrogen injection flow rate from the hydrogen tank 121 increases, and at the same time, the suction negative pressure increases and the anode off-gas suction flow rate also increases. Therefore, these are mixed, and the flow rate of hydrogen supplied to the fuel cell 110 (the portion capable of effectively generating electricity of the MEA) increases. Therefore, the portion of the MEA that can generate power effectively does not run out of fuel gas and can generate power satisfactorily.

  Further, since the injection cross-sectional area is increased, the suction flow rate of the anode off gas heated by the self-heating of the fuel cell 110 is also increased. The sucked high-temperature anode off gas is supplied to the fuel cell 110, so that the fuel cell 110 can be warmed up, and a portion where effective power generation due to freezing or the like is impossible can be eliminated.

  On the other hand, when it is determined that the output change amount is not equal to or greater than the switching threshold (S110 · No), the process proceeds to step S112, and the ECU 160 turns off the solenoid 71. Then, as shown in FIG. 2, the needle 40 moves forward with respect to the nozzle 30, and the injection cross-sectional area at the injection port 32 of the nozzle 30 becomes small. As a result, the amount of hydrogen injected from the hydrogen tank 121 decreases, and hydrogen is supplied to the fuel cell 110 at an appropriate flow rate.

  After the process of step S111 or step S112, in step S113, the ECU 160 detects the current system temperature T11 (temperature of the fuel cell 110) via the temperature sensor 132.

  Next, in step S114, the ECU 160 determines whether or not the system temperature T11 detected in step S113 is equal to or higher than a predetermined temperature T1. The predetermined temperature T1 is a temperature at which the control related to the change / correction of the switching threshold for increasing hydrogen can be completed, depends on the specifications of the fuel cell 110, and is obtained by a preliminary test and stored in the ECU 160. Has been. Such a predetermined temperature T1 is higher than the low temperature start determination temperature T0 in step S102, and is set to 30 ° C., for example.

  When it is determined that the system temperature T11 is equal to or higher than the predetermined temperature T1 (S114 / Yes), the process of the ECU 160 proceeds to step S104, ends the change / correction of the switching threshold, and based on the preset switching threshold. Switch to normal operation where the hydrogen flow rate is adjusted. Thereby, useless supply and consumption of hydrogen can be suppressed, and fuel consumption can be improved.

  On the other hand, when it is determined that the system temperature T11 is not equal to or higher than the predetermined temperature T1 (No at S114), the processing of the ECU 160 returns to Step S109 and repeats the processing of Steps S109, S110, S111 or S112, S113, and S114. That is, the change / correction of the switching threshold is continued until the system temperature T11 becomes equal to or higher than the predetermined temperature T1.

≪Effect of fuel cell system≫
According to the fuel cell system 1 according to the first embodiment as described above, the following effects can be mainly obtained.
(1) When the fuel cell system 1 is experiencing low temperature startup, the switching threshold is changed to a small threshold so that the flow rate of hydrogen to the fuel cell 110 increases even if the output change amount of the fuel cell 110 is small. Therefore, the fuel cell 110 can generate electric power satisfactorily while preventing a shortage of hydrogen in the fuel cell 110 (MEA capable of generating power effectively). And since it is hard to become short of hydrogen in this way, degradation of an electrolyte membrane is prevented and the lifetime can be extended.
(2) The ejector 10 includes an injection port adjustment mechanism with high control responsiveness in which the needle 40 is advanced and retracted by the solenoid 71 to change the injection cross-sectional area at the injection port 32, so that the flow rate of hydrogen is instantaneously controlled. Can do. In addition, since the high-temperature anode off gas (exhaust fuel gas) is circulated and supplied to the fuel cell 110 again, the fuel cell 110 can be warmed with the anode off gas.
(3) In addition, since the switching threshold is corrected based on the effective power generation area of the fuel cell 110 (MEA), the flow rate of hydrogen can be appropriately switched and supplied to the fuel cell 110.

  (4) When the system temperature T11 (temperature of the fuel cell 110) is equal to or higher than the predetermined temperature T1 and it is predicted that the reduction in the effective power generation area due to freezing or the like has been eliminated (S114 / Yes), the change / correction of the switching threshold is completed. Therefore, wasteful supply and consumption of hydrogen can be prevented.

  Although the preferred first embodiment of the present invention has been described above, the present invention is not limited to the first embodiment, and may be combined with the second embodiment described below without departing from the spirit of the present invention. And it can be changed as follows.

  In the first embodiment described above, the configuration is such that the position of the needle 40 is controlled and the hydrogen flow rate is adjusted based on the output change amount of the fuel cell 110 and the switching threshold value corresponding thereto. A differential pressure ΔP which is an absolute value of a difference between the target pressure of hydrogen in the flow path 111 and the actual pressure (measured pressure) detected by the pressure sensor 123 is detected (see FIG. 4, S109), and the detected differential pressure ΔP and the difference are detected. Based on the switching threshold corresponding to the pressure ΔP, the position of the needle 40 may be controlled to adjust the hydrogen flow rate (see S110 in FIG. 4). The target pressure is determined based on, for example, the depression amount of the accelerator pedal 152 and a map in which the depression amount and the target pressure are associated in advance. And it controls by the pressure-reduction valve (not shown) on the piping 122a so that it may become the determined target pressure.

  More specifically, it is considered that when the MEA has a portion where power generation is impossible and hydrogen is not properly consumed in the MEA, the actually measured pressure becomes higher than the target pressure and the differential pressure ΔP increases. When the fuel cell system 1 is experiencing low temperature startup, even if the actual differential pressure ΔP is small, the switching threshold is changed so that the hydrogen flow rate is increased (see arrow A1 in FIG. 5). Since the switching threshold is corrected in accordance with the power generation area (see arrow A2 in FIG. 5), even if the actual differential pressure ΔP is small, the solenoid 71 is turned on and the hydrogen flow rate to the fuel cell 110 increases. As a result, the fuel cell 110 can generate power without being short of hydrogen in the MEA.

  In the first embodiment described above, the case where the needle 40 is appropriately arranged at two positions with respect to the nozzle 30 and the injection cross-sectional area of the injection port 32 of the nozzle 30 is switched in two stages is illustrated, but the present invention is limited to this. Instead, as shown in FIG. 6, the injection cross-sectional area of the injection port 32 may be switched in three stages (multistage). More specifically, the needle 80 shown in FIG. 6 has a sharp pointed portion 81, a medium detail 82 thicker than the pointed portion 81, and a base end 83 thicker than the medium detail 82 toward the solenoid 71 side. I have.

Then, as shown in FIG. 6A, when the base end portion 83 is arranged on the surface of the injection port 32 by being urged by the compression coil spring 72, hydrogen is injected from the hydrogen tank 121 at the injection port 32. The cross-sectional area is the smallest, and when the medium detail 82 (see FIG. 6B) and the base end portion 83 (see FIG. 6C) are arranged, the cross-sectional area is designed to increase stepwise. In order to appropriately arrange the needle 80 at three positions with respect to the nozzle 30 as described above, two solenoids 71 and 71 are arranged in a line in the axial direction with respect to the needle 80, and the two solenoids are arranged. 71 and 71 can be configured by appropriately turning on and off.
In this way, by changing the hydrogen injection cross-sectional area in three stages, the hydrogen injection flow rate from the hydrogen tank 121 can be appropriately controlled in three stages. As a result, the hydrogen flow into the fuel cell 110 can be controlled. The flow rate can be controlled appropriately.

  In the first embodiment described above, the case where the moving body on which the fuel cell system 1 is mounted is an automobile (vehicle), but the moving body is not limited to this, and for example, a motorcycle, a train, a ship, and the like. It may be. In addition, the present invention may be applied to a stationary fuel cell system for home use or a fuel cell system incorporated in a hot water supply system.

In the first embodiment described above, when the system temperature T11 when the IG 151 is ON is lower than the low temperature start determination temperature T0 (Yes in S102), it is determined that the fuel cell system 1 needs to be started at a low temperature. (S105), the low temperature activation determination is not limited to this.
For example, while the fuel cell vehicle is stopped, the system temperature T11 of the fuel cell 110 is stored continuously or intermittently, and even if the temperature is higher than the low temperature start determination temperature T0 when the IG 151 is ON, the low temperature start determination temperature T0 It may be configured to determine that it is necessary to start at a low temperature when experiencing less than the above.

  In the first embodiment described above, the system temperature T11 (the temperature of the fuel cell 110) is detected by the temperature sensor 132 that detects the temperature of the cathode offgas. However, the present invention is not limited to this. In addition, a temperature sensor may be provided in the pipe 113b through which the refrigerant discharged from the fuel cell 110 flows or the fuel cell 110 itself to detect the temperature, or a plurality of temperature sensors may be provided to prevent erroneous detection. Good.

In the first embodiment described above, the case where the flow rate of hydrogen supplied to the fuel cell 110 is changed by changing the cross-sectional area of the nozzle 30 of the ejector 10 with the needle 40 is exemplified. A flow rate adjustment valve may be provided between the hydrogen tank 121 and the ejector 10, and the flow rate of hydrogen may be controlled by this flow rate adjustment valve.
In the case of a fuel cell system including a circulation pump on the pipe 124c (circulation flow path), for example, a configuration in which the flow rate of hydrogen is controlled by changing the rotation speed of the circulation pump may be employed.

<< Second Embodiment >>
Next, a second embodiment of the present invention will be described with reference to FIGS.
The mechanical configuration of the fuel cell system according to the second embodiment is the same as that of the fuel cell system 1 according to the first embodiment, but the program set in the ECU 160 is partially different and the operation thereof is partially different. . Hereinafter, the difference of the operation of the fuel cell system according to the second embodiment from that of the first embodiment will be described.

  The ECU 160 (required power generation amount detection means) according to the second embodiment receives fuel from the driver based on the depression amount of the accelerator pedal 152 by the driver and a map in which the depression amount and the requested acceleration are associated in advance. It has a function to calculate the required acceleration for battery cars. Then, ECU 160 calculates (detects) the required power generation amount for fuel cell 110 based on the calculated required acceleration and a map in which the required acceleration and the required power generation amount (required power generation amount) are associated in advance. It has a function. Further, a postscript flag A used for temporarily storing whether or not the engine has been started at a low temperature is 0 in the initial state.

As shown in FIG. 7, in step S <b> 205, which proceeds to the case of starting at a low temperature (S <b> 102 • Yes), the ECU 160 starts the fuel cell system 1 at a low temperature as in step S <b> 102 (see FIG. 4) of the first embodiment. Then, 1 is assigned to the flag A, and the fact that the low-temperature startup has been performed is temporarily stored.
Then, the processing of ECU 160 proceeds to step S206. In the second embodiment, after the fuel cell system 1 is normally activated in step S103, the process of the ECU 160 proceeds to step S206.

  In step S206, the ECU 160 refers to the flag A and determines whether or not the fuel cell system 1 has started at a low temperature. When the flag A is 1 and it is determined that the engine has been started at a low temperature (Yes at S206), the process of the ECU 160 proceeds to step S207. On the other hand, when it determines with not having started at low temperature (S206 * No), the process of ECU160 progresses to step S104.

In step S207, the ECU 160 resets the flag A (substitutes 0), and then detects the current system temperature T11 (S208).
In step S209, ECU 160 determines whether or not current system temperature T11 detected in step S208 is equal to or higher than predetermined temperature T2. The predetermined temperature T2 is a criterion for determining whether or not there is a possibility that there is a possibility that the MEA constituting the fuel cell 110 may not be able to generate power due to freezing or the like after the low temperature start-up, and a switching threshold described later. This temperature is used as a criterion for determining whether or not the change / correction can be completed, and is determined by a preliminary test depending on the specifications of the fuel cell 110 and stored in the ECU 160. Such a predetermined temperature T2 is higher than the low temperature start determination temperature T0 in step S102, and is set to 30 ° C., for example.

When it is determined that the current system temperature T11 is equal to or higher than the predetermined temperature T2 (S209 / Yes), the processing of the ECU 160 proceeds to step S104, and the ECU 160 does not change or correct the switching threshold, Drive to. In this case, there is no possibility that the MEA has a portion where power generation is not possible.
On the other hand, when the current system temperature T11 is not equal to or higher than the predetermined temperature T2 (S209 · No), the process of the ECU 160 proceeds to step S210. In this case, although the warm-up of the fuel cell 110 is promoted by the low-temperature start-up, there is a possibility that the MEA (fuel cell 110) may have a portion that cannot generate power.

  In step S210, the ECU 160 is supplied to the MEA capable of normal power generation even with a small required power generation amount in response to the fact that there is a possibility that there is a portion where the power generation is impossible in the MEA although it has experienced low-temperature startup. The switching threshold, which is a reference for switching the hydrogen flow rate, is changed to a small value so that the hydrogen flow rate increases (see arrow A1 in FIG. 8).

  After that, the ECU 160 estimates the effective power generation area of the MEA constituting the fuel cell 110 (S107), and corrects the switching threshold based on the estimated effective power generation area in step S211 (see arrow A2 in FIG. 8). Specifically, when the estimated effective power generation area is smaller than the reference standard effective power generation area with no portion where power generation is not possible, even a small required power generation amount is supplied to an MEA that can generate power effectively. Change to a small switching threshold so that the hydrogen flow rate increases. On the other hand, when the estimated effective power generation area is larger than the reference effective power generation area, the switching threshold is changed to a large switching threshold so that the flow rate of hydrogen supplied to the MEA capable of effectively generating power is reduced.

  In step S212, ECU 160 calculates the requested acceleration from the driver based on the depression amount of accelerator pedal 152 and a map in which the depression amount and the requested acceleration from the driver are associated in advance. Subsequently, ECU 160 calculates (detects) the required power generation amount for fuel cell 110 based on the calculated required acceleration and a map in which the required acceleration and the required power generation amount (required power generation amount) are associated in advance. To do.

  Next, in step S213, the ECU 160 changes the required power generation amount obtained in step S212 above the switching threshold that is changed based on the experience of low-temperature startup (S210) and corrected based on the effective power generation area (S211). It is determined whether or not.

When it determines with request | requirement electric power generation amount being more than a switching threshold value (S213 * Yes), it progresses to step S111 and ECU160 turns ON the solenoid 71 of the ejector 10. FIG. Then, as shown in FIG. 3, the needle 40 moves backward with respect to the nozzle 30, thereby increasing the injection flow rate of hydrogen from the hydrogen tank 121. Therefore, the portion of the MEA that can generate power effectively does not run out of fuel gas and can generate power well, and the fuel cell 110 can generate power corresponding to the required acceleration (required power generation amount).
Thereafter, the processing of ECU 160 proceeds to step S208.

On the other hand, when it determines with request | requirement electric power generation amount not being more than a switching threshold value (S213 * No), it progresses to step S112 and ECU160 turns OFF the solenoid 71. FIG. Then, as shown in FIG. 2, the needle 40 moves forward with respect to the nozzle 30, and the injection cross-sectional area at the injection port 32 of the nozzle 30 becomes small. As a result, the amount of hydrogen injected from the hydrogen tank 121 decreases, and hydrogen is supplied to the fuel cell 110 at an appropriate flow rate.
Thereafter, the processing of ECU 160 proceeds to step S208.

  Thereafter, while the processing of step S208 to step S111 or step S112 is repeated, the fuel cell 110 is further warmed up and the system temperature T11 (temperature of the fuel cell 110) becomes equal to or higher than the predetermined temperature T2 (S209). • Yes), switching to normal operation without changing / correcting the switching threshold (S104). That is, when the system temperature T11 becomes equal to or higher than the predetermined temperature T2, the change of the switching threshold for increasing the flow rate of hydrogen is stopped, so that wasteful control is stopped and wasteful supply and consumption of hydrogen are stopped. Can be suppressed and fuel consumption can be improved.

1 is a configuration diagram of a fuel cell system according to a first embodiment. FIG. It is a sectional side view of the ejector concerning a 1st embodiment, and shows a state where a solenoid is turned off and a hydrogen injection port (injection cross-sectional area) in a nozzle is small. It is a sectional side view of the ejector concerning a 1st embodiment, and shows a state where a solenoid is turned ON and a hydrogen injection port (injection cross-sectional area) in a nozzle is large. It is a flowchart which shows operation | movement of the fuel cell system which concerns on 1st Embodiment. It is a graph which shows typically a change threshold concerning a 1st embodiment. It is a sectional side view which shows the relationship between the nozzle and needle which concern on the modification of 1st Embodiment, (a) is a state with the small hydrogen injection port (injection cross-sectional area) in a nozzle, (b) is an injection port inside. (C) shows a state where the injection port is large. It is a flowchart which shows operation | movement of the fuel cell system which concerns on 2nd Embodiment. It is a graph which shows typically a change threshold concerning a 2nd embodiment.

Explanation of symbols

1 Fuel cell system 10 Ejector (Fuel gas flow rate adjusting means)
30 nozzles (spout adjustment mechanism)
32 injection port 40 needle (injection port adjustment mechanism)
71 Solenoid (Jet adjustment mechanism)
72 Compression coil spring (Jet adjustment mechanism)
110 Fuel cell 121 Hydrogen tank (fuel gas source)
121a, 122a, 10a piping (fuel gas supply flow path)
123 Pressure sensor 124 Purge valve 124c Piping (circulation flow path)
132 Temperature sensor (Fuel cell temperature detection means)
141 travel motor 152 accelerator pedal 160 ECU (power generation state detection means, required power generation amount detection means, fuel gas flow rate adjustment means, effective power generation area estimation means)
T1 Predetermined temperature T11 Current fuel cell temperature

Claims (6)

Including a fuel cell which fuel gas and oxidant gas to generate electric power by being supplied, and the cold start to accelerate the warm-up of the fuel cell when a predetermined condition is satisfied during startup, when the predetermined condition is not satisfied A fuel cell system that normally starts
A power generation state detecting means for detecting an output change amount of the fuel cell as a power generation state of the fuel cell;
Fuel gas flow rate adjusting means for adjusting the flow rate of the fuel gas supplied to the fuel cell so as to increase or decrease in stages ;
An effective power generation area estimating means for estimating an effective power generation area of the fuel cell;
A switching threshold which is a predetermined output change amount and serves as a switching reference when the fuel gas flow rate adjusting means gradually increases or decreases the flow rate of the fuel gas;
With
When starting at low temperature,
The fuel gas flow rate adjusting means is
Change to a switching threshold value that is smaller than the normal startup so that the fuel gas flow rate increases.
Based on the effective power generation area estimated by the effective power generation area estimation means, further correct the switching threshold after the change so that the switching threshold decreases as the effective power generation area decreases,
A fuel cell system, wherein the flow rate of the fuel gas is increased or decreased based on the corrected switching threshold and the power generation state of the fuel cell detected by the power generation state detection means . Including a fuel cell which fuel gas and oxidant gas to generate electric power by being supplied, and the cold start to accelerate the warm-up of the fuel cell when a predetermined condition is satisfied during startup, when the predetermined condition is not satisfied A fuel cell system that normally starts
Power generation state detection means for detecting a differential pressure between a target pressure of fuel gas supplied to the fuel cell and an actually measured pressure as a power generation state of the fuel cell;
Fuel gas flow rate adjusting means for adjusting the flow rate of the fuel gas supplied to the fuel cell so as to increase or decrease in stages ;
An effective power generation area estimating means for estimating an effective power generation area of the fuel cell;
A switching threshold that is a predetermined differential pressure and serves as a switching reference when the fuel gas flow rate adjusting means increases or decreases the fuel gas flow rate stepwise;
With
When starting at low temperature,
The fuel gas flow rate adjusting means is
Change to a switching threshold value that is smaller than the normal startup so that the fuel gas flow rate increases.
Based on the effective power generation area estimated by the effective power generation area estimation means, further correct the switching threshold after the change so that the switching threshold decreases as the effective power generation area decreases,
A fuel cell system, wherein the flow rate of the fuel gas is increased or decreased based on the corrected switching threshold and the power generation state of the fuel cell detected by the power generation state detection means . Including a fuel cell which fuel gas and oxidant gas to generate electric power by being supplied, if the cold start and the predetermined condition for promoting warm-up of the fuel cell when a predetermined condition is satisfied when starting is not satisfied A fuel cell system that normally starts ,
A required power generation amount detecting means for detecting a required power generation amount required for the fuel cell;
Fuel gas flow rate adjusting means for adjusting the flow rate of the fuel gas supplied to the fuel cell so as to increase or decrease in stages ;
An effective power generation area estimating means for estimating an effective power generation area of the fuel cell;
A switching threshold that is a predetermined required power generation amount and serves as a switching reference when the fuel gas flow rate adjusting means increases or decreases the flow rate of the fuel gas stepwise;
With
When starting at low temperature,
The fuel gas flow rate adjusting means is
Change to a switching threshold value that is smaller than the normal startup so that the fuel gas flow rate increases.
Based on the effective power generation area estimated by the effective power generation area estimation means, further correct the switching threshold after the change so that the switching threshold decreases as the effective power generation area decreases,
A fuel cell system, wherein the flow rate of the fuel gas is increased or decreased based on the corrected switching threshold and the required power generation amount detected by the required power generation amount detection means . The fuel cell system according to claim 3 is a system mounted on a moving body, and the moving body moves based on the generated power of the fuel cell,
The required power generation amount is calculated based on a required acceleration required for the moving body. A circulation flow path for circulating the fuel gas by returning the discharged fuel gas discharged from the fuel cell to the fuel gas supply flow path through which the fuel gas supplied from the fuel gas source to the fuel cell flows;
The nozzle is provided at the junction of the fuel gas supply channel and the circulation channel, and injects fuel gas from the fuel gas source. From the fuel gas from the fuel gas source and the circulation channel An ejector that mixes with the exhaust fuel gas of
With
The ejector includes an injection port adjustment mechanism that adjusts an injection cross-sectional area at an injection port of the nozzle, and an injection cross-sectional area at the injection port of the nozzle is adjusted by the injection port adjustment mechanism. The fuel cell system according to any one of claims 1 to 4 , wherein a flow rate of the fuel gas is adjusted. A fuel cell temperature detecting means for detecting the temperature of the fuel cell;
The fuel according to any one of claims 1 to 5, wherein the fuel gas flow rate adjusting means continues changing the switching threshold until a temperature of the fuel cell becomes equal to or higher than a predetermined temperature. Battery system.

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