JP2008198440A - Fuel cell system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To detect certainly a closure state due to freezing at a joining part of a fuel gas passage and a circulation route. <P>SOLUTION: A pressure change speed after closure of a hydrogen injector 45 is obtained by a detected value of a pressure sensor 44, and, based on this pressure change speed, an effective diameter of a pipe at the joining part 58 is obtained. When this effective diameter is predicted to show a closure state due to freezing at the joining part 58, a hydrogen pump 55 is forcibly driven to supply a fuel gas to the joining part 58, and by an adiabatic expansion of air passing through the small effective diameter closed at the joining part 58, the joining part is heated and freezing of the joining part 58 is released. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a fuel cell system having a fuel gas supply path for supplying fuel gas to a fuel cell and a circulation path for returning fuel off-gas discharged from the fuel cell to the fuel gas supply path.

  An example of a fuel cell that generates electricity using an electrochemical reaction between hydrogen and oxygen is a polymer electrolyte fuel cell. The polymer electrolyte fuel cell includes a stack configured by stacking a plurality of cells. The cell constituting the stack includes an anode (fuel electrode) and a cathode (air electrode), and a solid polymer electrolyte membrane having a sulfone sun group as an ion exchange group is provided between the anode and the cathode. Intervene.

  A fuel gas containing a fuel gas (hydrogen gas or reformed hydrogen made by reforming hydrocarbons to be hydrogen rich) is supplied to the anode, and a gas containing oxygen as an oxidant (oxidant gas), for example, to the cathode. Air is supplied. By supplying the fuel gas to the anode, hydrogen contained in the fuel gas reacts with the catalyst of the catalyst layer constituting the anode, thereby generating hydrogen ions. The generated hydrogen ions pass through the solid polymer electrolyte membrane and cause an electrical reaction with oxygen at the cathode. Power generation is performed by this electrochemical reaction.

  By the way, in a fuel cell system using a polymer electrolyte fuel cell as a power source, when the operation of the system is stopped, the temperature of the fuel cell decreases, and moisture inside the fuel cell that has been in a hot and humid state condenses and dew condensation occurs. Or it may freeze. For this reason, when the operation of the system is stopped, scavenging is performed to discharge water from the reaction gas flow path of the fuel cell.

  At the time of starting below the freezing point, a warm-up operation is performed in which the amount of oxidant gas supplied to the fuel cell is reduced to increase the heat generation amount. In the warm-up operation, the fuel gas from the fuel gas supply path is at the junction of the fuel gas supply path for supplying the fuel gas to the fuel cell and the circulation path for returning the fuel off-gas discharged from the fuel cell to the fuel gas supply path. The temperature is lowered by the outside air temperature, and the temperature of the fuel gas at the junction may be lower than 0 ° C. Under such circumstances, the gas containing water vapor from the circulation path is frozen in the joining portion to generate ice, and as the ice grows, the effective diameter in the joining portion decreases, and in some cases, the flow path in the joining portion May be blocked. When the flow path at the junction is closed, the fuel gas is not supplied to the fuel cell, and the fuel cell cannot generate power.

  Therefore, when there is a possibility that freezing may occur at the junction between the hydrogen supply path and the circulation path, an amount of heat contained in the circulation gas is increased to prevent freezing at the junction. (See Patent Document 1).

JP 2005-332676 A

  However, what is described in Patent Document 1 detects the freezing in the joining portion based on the temperature, and therefore measures are taken to increase the amount of heat contained in the circulating gas even though the joining portion is not frozen. If this measure is taken, energy will be wasted.

  Therefore, an object of the present invention is to reliably detect a closed state due to freezing at a junction between a fuel gas flow path and a circulation path.

  In order to solve the above-described problems, the present invention provides a fuel gas flow path provided with opening / closing means for supplying fuel gas to a fuel cell, and fuel discharged from the fuel cell at a junction at a downstream side of the opening / closing means. A fuel cell system having a circulation path through which off-gas joins, a pressure detection unit that detects a pressure between the opening / closing means and the junction, and a pressure state detected by the pressure detection unit And a control unit that estimates a closed state due to freezing in the merging unit.

  According to such a configuration, since the closed state due to freezing in the confluence portion is estimated based on the state of the pressure between the opening / closing means and the confluence portion, it is ensured that the confluence portion is closed due to freezing. Can be detected. Therefore, it is possible to prevent the measure for increasing the amount of heat contained in the fuel gas from being taken even though the joining portion is not frozen.

  In configuring the fuel cell system, the following elements can be added.

  Suitably, the said control part estimates the closed state of the said confluence | merging part based on the pressure change speed after the said opening / closing means is closed.

  According to such a configuration, since the closed state of the merging portion is estimated based on the pressure change rate after the opening / closing means is closed, it is possible to reliably detect that the merging portion is closed with freezing. .

  Suitably, the said control part estimates the closed state of the said confluence | merging part based on the amount of pressure changes after the said opening / closing means is open | released.

  According to such a configuration, since the closed state of the merging portion is estimated based on the pressure change rate after the opening / closing means is closed, it is possible to reliably detect that the merging portion is closed with freezing. .

  Preferably, the apparatus includes a drive unit that forcibly circulates the fuel gas, and the control unit drives and circulates the drive unit when it is estimated that the merging unit is frozen from a closed state of the merging unit. Freezing is released by increasing the amount of heat of the gas.

  According to such a configuration, when it is estimated that the merging portion is frozen from the closed state of the merging portion, the amount of heat of the fuel gas circulating by driving the driving portion is increased, thereby reliably releasing the merging portion from freezing. be able to.

  Preferably, a temperature sensor that detects the temperature of the fuel cell, and a current sensor that detects an output current of the fuel cell, the control unit is freezing from the closed state of the junction unit to the junction unit Even if it is estimated that the opening / closing means is abnormal, it is determined that there is no freezing based on the relationship between the temperature detected by the temperature sensor and the output current detected by the current sensor.

  According to such a configuration, even when it is estimated that the merging portion is frozen from the closed state of the merging portion, an abnormality in the opening / closing means may occur when the condition where the frosting cannot occur due to the relationship between the temperature of the fuel cell and the output current of the fuel cell. By determining, it is possible to prevent an erroneous determination that the merging portion is frozen even though the merging portion is not frozen.

  According to the present invention, since the closed state due to freezing in the joining portion is estimated based on the pressure state between the opening / closing means provided in the fuel gas supply path and the joining portion, the joining portion is closed along with freezing. It is possible to reliably detect the state.

Next, a preferred embodiment of the present invention will be described.
FIG. 1 is a system configuration diagram of a fuel cell system to which the present invention is applied.
In FIG. 1, a fuel cell system 10 includes a fuel gas supply system 4 for supplying a fuel gas (hydrogen gas) to the fuel cell 20 and an oxidizing gas supply system for supplying an oxidizing gas (air) to the fuel cell 20. 7, a coolant supply system 3 for cooling the fuel cell 20, and a power system 9 for charging / discharging generated power from the fuel cell 20.

  The fuel cell 20 is a membrane / electrode assembly in which an anode electrode 22 and a cathode electrode 23 are formed by screen printing or the like on both surfaces of a polymer electrolyte membrane 21 made of a proton conductive ion exchange membrane or the like formed of a fluorine-based resin or the like. 24. Both surfaces of the membrane / electrode assembly 24 are sandwiched by separators (not shown) having flow paths of fuel gas, oxidizing gas, and cooling water, and grooves are respectively formed between the separator and the anode electrode 22 and the cathode electrode 23. An anode gas channel 25 and a cathode gas channel 26 are formed. The anode electrode 22 is configured by providing a fuel electrode catalyst layer on a porous support layer, and the cathode electrode 23 is configured by providing an air electrode catalyst layer on the porous support layer. The catalyst layers of these electrodes are configured by adhering platinum particles, for example.

The anode electrode 22 undergoes an oxidation reaction of the following formula (1), and the cathode electrode 23 undergoes a reduction reaction of the following formula (2). In the fuel cell 20 as a whole, an electromotive reaction of the following formula (3) occurs.
H ₂ → 2H ⁺ + 2e ⁻ (1)
(1/2) O ₂ + 2H ⁺ + 2e ⁻ → H ₂ O (2)
H ₂ + (1/2) O ₂ → H ₂ O (3)

  In FIG. 1, for convenience of explanation, the structure of a unit cell composed of a membrane / electrode assembly 24, an anode gas channel 25, and a cathode gas channel 26 is schematically shown. A plurality of unit cells connected in series.

  The coolant supply system 3 of the fuel cell system 10 includes a cooling path 31 for circulating the coolant, a temperature sensor 32 for detecting the temperature of the coolant drained from the fuel cell 20, and a radiator for radiating the heat of the coolant to the outside. (Heat exchanger) 33, a valve 34 for adjusting the amount of coolant flowing into the radiator 33, a coolant pump 35 for pressurizing and circulating the coolant, and a temperature for detecting the temperature of the coolant supplied to the fuel cell 20 A sensor 36 and the like are provided.

  The fuel gas supply system 4 of the fuel cell system 10 includes a fuel gas flow path 40 for supplying fuel gas (anode gas), for example, hydrogen gas, from the fuel gas supply device 42 to the anode gas channel 25, and an anode gas. A circulation passage (circulation passage) 51 for circulating the fuel off-gas exhausted from the channel 25 to the fuel gas passage 40 is piped, and a fuel gas circulation system is constituted by these gas passages.

  The fuel gas passage 40 includes a shutoff valve (original valve) 43 that controls the outflow of fuel gas from the fuel gas supply device 42, and a portion near the junction 58 between the fuel gas passage 40 and the circulation passage (circulation passage) 51. A pressure sensor 44 for detecting the pressure of the fuel gas, a hydrogen injector 45 as an opening / closing means for supplying the fuel gas discharged from the shutoff valve 43 to the fuel cell 20 according to an on / off operation, and a shutoff for controlling the fuel gas supply to the fuel cell 20 A valve 46 is installed.

  The fuel gas supply device 42 includes, for example, a high-pressure hydrogen tank, a hydrogen storage alloy, a reformer, and the like. The circulation channel 51 includes a shut-off valve 52 that controls the supply of fuel off-gas from the fuel cell 20 to the circulation channel 51, a gas-liquid separator 53 and a discharge valve 54 that removes water contained in the fuel off-gas, and an anode gas channel 25. The hydrogen pump (circulation pump) 55 that compresses the fuel off-gas that has undergone pressure loss and raises the pressure to an appropriate gas pressure when returning to the fuel gas passage 40 when passing through the fuel gas, and the fuel gas in the fuel gas passage 40 Is installed in the reverse flow prevention valve 56 for preventing the reverse flow from the merging portion 58 to the circulation flow path 51 side. By driving the hydrogen pump 55 with a motor, the fuel off-gas generated by driving the hydrogen pump 55 merges with the fuel gas supplied from the fuel gas supply device 42 in the fuel gas flow path 40 at the merging portion 58, and then the fuel cell 20. To be reused.

  The hydrogen pump 55 is provided with a rotation speed sensor 57 that detects the rotation speed of the hydrogen pump 55.

  Further, an exhaust passage 61 for branching the fuel off-gas exhausted from the fuel cell 20 to the outside of the vehicle via a diluter (for example, a hydrogen concentration reducing device) 62 is branched and connected to the circulation passage 51. Yes. A purge valve 63 is installed in the exhaust passage 61, and is configured to perform exhaust control of the fuel off gas. By opening and closing the purge valve 63, it is possible to repeatedly circulate in the fuel cell 20, discharge the fuel off-gas having increased impurity concentration to the outside, and introduce new fuel gas to prevent the cell voltage from decreasing. . It is also possible to remove the water accumulated in the gas flow path by causing a pulsation in the internal pressure of the circulation flow path 51.

  On the other hand, the oxidizing gas supply system 7 of the fuel cell system 10 exhausts an oxidizing gas passage 71 for supplying an oxidizing gas (cathode gas) to the cathode gas channel 26 and a cathode off-gas exhausted from the cathode gas channel 26. A cathode off-gas flow path 72 is provided for this purpose. An air cleaner 74 that takes in air from the atmosphere and an air compressor 75 that compresses the taken air and supplies the compressed air as an oxidant gas to the cathode gas channel 26 are set in the oxidizing gas channel 71. The air compressor 75 is provided with a rotation speed sensor 73 that detects the rotation speed of the air compressor 75. A humidifier 76 for exchanging humidity is provided between the oxidizing gas channel 71 and the cathode offgas channel 72. The cathode offgas passage 72 is provided with a pressure regulating valve 77 that adjusts the exhaust pressure of the cathode offgas passage 72, a gas-liquid separator 78 that removes moisture in the cathode offgas, and a muffler 79 that absorbs the exhaust sound of the cathode offgas. ing. The cathode off-gas discharged from the gas-liquid separator 78 is diverted. One of the cathode off-gas flows into the diluter 62 and is mixed and diluted with the fuel off-gas staying in the diluter 62. Is mixed with the gas diluted by the diluter 62 and discharged outside the vehicle.

  Further, the power system 9 of the fuel cell system 10 has a DC-DC converter 90 in which the output terminal of the battery 91 is connected to the primary side and the output terminal of the fuel cell 20 is connected to the secondary side, and a surplus as a secondary battery. A battery 91 that stores electric power, a battery computer 92 that monitors the charging state of the battery 91, an inverter 93 that supplies AC power to a load or driving vehicle 94 of the fuel cell 20, and various high voltages of the fuel cell system 10 An inverter 95 that supplies AC power to the auxiliary machine 96, a voltage sensor 97 that measures the output voltage of the fuel cell 20, and a current sensor 98 that measures the output current are connected.

  The DC-DC converter 90 converts the surplus power of the fuel cell 20 or the regenerative power generated by the braking operation to the vehicle travel motor 94 into a voltage and supplies it to the battery 91 for charging. Further, in order to compensate for the shortage of the generated power of the fuel cell 20 with respect to the required power of the vehicle travel motor 94, the DC-DC converter 90 converts the discharged power from the battery 91 to a secondary side after voltage conversion. .

  Inverters 93 and 95 convert the direct current into a three-phase alternating current and output the three-phase alternating current to vehicle running motor 94 and high voltage auxiliary machine 96, respectively. The vehicle travel motor 94 is provided with a rotational speed sensor 99 that detects the rotational speed of the motor 94. The wheel 94 is mechanically coupled to the motor 94 via a differential, and the rotational force of the motor 94 can be converted into the driving force of the vehicle.

  The voltage sensor 97 and the current sensor 98 are for measuring the AC impedance based on the phase and amplitude of the current with respect to the voltage in the AC signal superimposed on the power system. The AC impedance corresponds to the water content of the fuel cell 20.

  Further, the fuel cell system 10 is provided with a control unit 80 for controlling the power generation of the fuel cell 12.

  The control unit 80 is configured by a general-purpose computer including a CPU (Central Processing Unit), a RAM, a ROM, an interface circuit, and the like, for example, and includes temperature sensors 32 and 36, a pressure sensor 44, and rotation speed sensors 57, 73, and 99. Sensor signals from the sensor, signals from the voltage sensor 97, current sensor 98, and ignition switch 82, and the motors are driven in accordance with the battery operating state, for example, the power load, so that the hydrogen pump 55 and the air compressor 75 are rotated. The number is adjusted, and further, opening / closing control of various valves or adjustment of the valve opening degree is performed.

  In addition, the control unit 80 estimates a closed state due to freezing in the merging unit 58 based on the pressure state detected by the pressure sensor 44 as a pressure detecting unit that detects the pressure between the hydrogen injector 45 and the merging unit 58. It is configured as follows.

  For example, the control unit 80 estimates the closed state due to freezing in the merging unit 58 based on the pressure change rate after the hydrogen injector 45 is closed (after turning off), or the pressure after the hydrogen injector 45 is opened (after turning on). A closed state due to freezing in the merging portion 58 is estimated based on the amount of change.

  When the closed state due to freezing in the merging unit 58 is estimated, the control unit 80 drives the hydrogen pump 55 as a driving unit for forcibly circulating the fuel gas to increase the amount of heat of the fuel gas, thereby freezing in the merging unit 58. Is going to be released. On the other hand, even when it is estimated that the merging unit 58 is frozen, the control unit 80 generates an abnormality in the pressure change when the condition is such that the temperature of the fuel cell 20 and the output current cannot be frozen. It is determined that the hydrogen injector 45 is abnormal.

  Specifically, as shown in FIG. 2A, the hydrogen injector 45 repeatedly turns on and off as an opening / closing means to supply a required amount of fuel gas (hydrogen gas) to the fuel gas flow path 40 and the junction 58. It is like that. When the pressure sensor 44 detects the pressure on the upstream side of the merging portion 58 associated with the on / off of the hydrogen injector 45, the detection output of the pressure sensor 44 exhibits characteristics as shown in FIG. When the merging portion 58 is closed by freezing, the characteristics shown in FIG. 2B and 2C, the pressure change rate accompanying the detection of the pressure sensor 44 is represented by a pressure change amount ΔP per unit time ΔT after the hydrogen injector 45 is closed. That is, the pressure change rate (pressure change rate) ΔP / ΔT after closing of the hydrogen injector 45 is different between the normal time and the closed time, and is larger in the closed time than in the normal time. Based on the speed (pressure change rate) ΔP / ΔT, it is possible to estimate a closed state due to freezing in the merging portion 58.

  Further, in the present embodiment, focusing on the fact that the ice adhesion state at the merging portion 58 has a correlation with the effective diameter of the tube at the merging portion 58, the effective diameter of the tube at the merging portion 58 is changed to the gap between the tubes due to freezing. As the area, the closed state of the merging portion is determined according to the following equation (1). Specifically, when the expression (1) is not satisfied, it is estimated that the merging portion 58 is in a normal state, and when the expression (1) is satisfied, it is estimated that the merging portion 58 is in a closed state due to freezing.

  ΔP × (stack volume + circulation volume) / atmospheric pressure−hydrogen consumption (l / S) × ΔT> determination threshold value (1)

  Here, the stack volume and the circulation volume on the left side of the formula (1) are the volumes downstream of the hydrogen injector 45, and can be obtained in advance as the stack capacity of the fuel cell 20 + the capacity of the circulation path 51. .3. The hydrogen consumption can be estimated from the power generation voltage of the fuel cell 20. The determination threshold value on the right side of equation (1) is a value that can be arbitrarily set according to the system. When the closed state of the junction is determined to be “abnormal”, the left side of equation (1) is Set the minimum value shown.

  In the equation (1), the effective diameter of the pipe in the merging portion 58 is determined based on the pressure change amount ΔP per unit time ΔT after the hydrogen injector 45 is closed. The diameter may be directly calculated, and the determination may be made based on the magnitude relationship between the effective diameter and the threshold value for determining the closed state.

  Further, instead of the equation (1), the effective diameter of the pipe at the merging portion 58 can be determined using a pressure change (increase) after the hydrogen injector 45 is opened. That is, it is possible to estimate the ice adhesion state based on the pressure change when the hydrogen injector 45 is opened.

(Description of operation)
Next, the effect | action in Embodiment 1 is demonstrated according to the flowchart of FIG.
First, in step S1, the control unit 80 takes in the detection output of the pressure sensor 44 in order to monitor the closed state (closed state) of the merging unit 58, and based on the pressure change amount ΔP and the elapsed time ΔT from the previous time. , (1) is determined whether it is satisfied.

  In step S1, the control unit 80 ends the process when the expression (1) is not satisfied (NO), that is, when it can be determined that the merging unit has no closed state and is normal, the expression (1) is satisfied. If it is determined (YES), that is, if it is possible to estimate the blockage state of the merging portion and determine that it is abnormal, the process proceeds to the process of eliminating the blockage state by freezing.

  First, in step S <b> 2, the control unit 80 estimates a closed state due to freezing in the merging unit 58. That is, the control unit 80 calculates the pressure change rate (pressure change rate) ΔP / ΔT after the hydrogen injector 45 is closed from ΔP and ΔT used in the determination of the expression (1), and calculates the calculated pressure change rate ΔP / ΔT. Based on the above, as the effective diameter in the merging portion 58, the gap area of the pipe accompanying freezing is calculated.

  Next, in step S3, the control unit 80 performs a calculation process of the suppliable hydrogen amount Q1. For example, the amount of hydrogen that can be supplied by the hydrogen injector 45 and the flow rate Δq per unit time when the hydrogen injector 45 is opened × the valve opening time is obtained as the supplyable hydrogen amount Q. Next, in step S4, the control unit 80 calculates a necessary hydrogen flow rate Qreq. This required hydrogen flow rate Qreq can be obtained as the amount of hydrogen gas to be supplied to the fuel cell 20 in order to compensate for the difference between the required power amount required for the entire system and the current generated power.

  Next, in step S5, the control unit 80 determines whether or not the suppliable hydrogen amount Q1 is less than the required hydrogen flow rate Qreq. As a result of this determination, when it is determined that Q1 is smaller than Qreq (YES), the control unit 80 proceeds to step S6 and takes in the detected temperatures of the temperature sensors 32 and 36 and the detected current of the current sensor 98. Next, the process proceeds to step S7, and the control unit 80 determines whether or not the condition belongs to the zone Z1 and can be frozen from the relationship between the water temperature and the generated currents I1 and I2, as shown in FIG. As a result of this determination, when it is determined that the conditions are not likely to be frozen (NO), the control unit 80 proceeds to step S8, and even in the condition that the merging unit 58 is estimated to be frozen, the merging unit 58 It is determined that the abnormality accompanying the pressure change is caused by the abnormality of the hydrogen injector 45, and the processing in this routine is terminated.

  When it is determined in step S5 that the supplyable hydrogen amount Q1 is equal to or greater than the necessary hydrogen flow rate Qreq (NO), the control unit 80 determines that there is no shortage of fuel gas and performs the processing in this routine. finish.

  On the other hand, when it is determined in step S7 that the condition may cause freezing (YES), the control unit 80 proceeds to step S9 and determines that the merging unit 58 is frozen. In this case, as a determination result that the merging unit 58 is frozen, the control unit 80 displays a message to that effect on the display panel (not shown), performs a process for stopping the system. Can be.

  Next, the process proceeds to step S <b> 10, and the control unit 80 drives the hydrogen pump 55 with the freezing of the merging unit 58, forcibly supplies the fuel gas to the merging unit 58, and is small blocked by the merging unit 58. The merging portion 58 is heated by adiabatic expansion of the air passing through the effective diameter to defrost the ice in the merging portion 58, and the processing in this routine ends.

  According to the present embodiment, since the closed state due to freezing in the merging portion 58 is estimated based on the pressure change rate after the hydrogen injector 45 is closed, the closed state due to freezing of the merging portion 58 can be reliably detected. it can. Therefore, it is possible to prevent the measure for increasing the fuel contained in the fuel gas from being taken even though the junction 58 is not frozen, and to prevent wasteful consumption of energy. It becomes possible.

  Further, according to the present embodiment, when it is determined that the merging portion 58 is frozen, the hydrogen pump 55 is driven to forcibly supply the fuel gas to the merging portion 58, so that the ice in the merging portion 58 is surely supplied. It can be thawed and the reliability of the fuel cell 20 can be improved.

  Furthermore, according to the present embodiment, even when it is estimated that the merging portion 58 is frozen, it is determined that the hydrogen injector 45 is abnormal under the condition that the temperature cannot be frozen due to the relationship between the temperature and the output current. It is possible to prevent erroneous determination that the merging portion 58 is frozen even though the merging portion 58 is not frozen.

(Embodiment 2)
Next, Embodiment 2 will be described with reference to FIG. In the present embodiment, the closed state due to freezing in the merging portion 58 is estimated based on the pressure change amount after the hydrogen injector 45 is opened, and other configurations are the same as those in the first embodiment.

  Specifically, as shown in FIG. 4, when the hydrogen injector 45 is in the valve open (ON) state, the pressure at the merging portion 58 is the pressure P1 when it is normal, but becomes the pressure P2 when it is closed. There is a relationship of P2 <P1. P1 is a target pressure when the merging portion 58 is normal, P2 is a target pressure when the merging portion 58 is closed, a pressure downstream of the hydrogen injector 45 is detected by the pressure sensor 44, and the detected pressure is the pressure P1 or the pressure P2. By determining whether or not to become, the control unit 80 can reliably detect the closed state due to freezing in the merging unit 58 based on the pressure change amount after the hydrogen injector 45 is opened.

  According to this embodiment, in addition to the same effects as in the first embodiment, the closed state due to freezing in the merging portion 58 can be reliably detected based on the amount of pressure change after the hydrogen injector 45 is opened.

1 is a system configuration diagram of a fuel cell system according to the present invention. It is a wave form diagram for demonstrating the pressure change speed after closure of the hydrogen injector in Embodiment 1. FIG. 5 is a flowchart for explaining an operation in the first embodiment. FIG. 6 is a waveform diagram for explaining a pressure change amount after the hydrogen injector is opened in the second embodiment.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 Fuel cell system, 20 Fuel cell, 40 Fuel gas flow path, 44 Pressure sensor, 45 Hydrogen injector, 55 Hydrogen pump, 58 Junction part, 80 Control part

Claims (5)

A fuel cell system having a fuel gas flow path provided with an opening / closing means for supplying fuel gas to the fuel cell, and a circulation path through which the fuel off-gas discharged from the fuel cell joins at a merging portion downstream of the opening / closing means Because
A pressure detection unit for detecting a pressure between the opening / closing means and the merging unit;
And a control unit that estimates a closed state due to freezing in the merging portion based on a pressure state detected by the pressure detection unit. The fuel cell system according to claim 1, wherein
The fuel cell system according to claim 1, wherein the control unit estimates a closed state of the merging unit based on a pressure change rate after the opening / closing means is closed. The fuel cell system according to claim 1, wherein
The fuel cell system according to claim 1, wherein the control unit estimates a closed state of the merging unit based on a pressure change amount after the opening / closing means is opened. The fuel cell system according to any one of claims 1, 2, and 3,
A drive unit for forcibly circulating the fuel gas;
The controller is configured to release the freezing by increasing the amount of heat of the circulating fuel gas by driving the driving unit when it is estimated that the converging unit is frozen from the closed state of the converging unit. A fuel cell system. The fuel cell system according to any one of claims 1, 2, and 3,
A temperature sensor for detecting the temperature of the fuel cell;
A current sensor for detecting an output current of the fuel cell,
Even when the control unit estimates that the joining portion is frozen from the closed state of the joining portion, there is freezing due to the relationship between the temperature detected by the temperature sensor and the output current detected by the current sensor. A fuel cell system characterized in that when the condition is not obtained, it is determined that the opening / closing means is abnormal.

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