JP2008262873A - Fuel cell system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To set up a proper gas leak measurement time for an assumed gas leak amount or a detectable gas leak amount. <P>SOLUTION: The gas leak measurement time is set based on a ratio of detectable gas leak amounts (Q1, Q2) found at each sensor detecting a gas leak at prescribed gas leak assumption sites (P1, P2) to lapses of time (T1, T2) from a time when the gas leak is generated at the gas leak assumption sites (P1, P2) until a time when gas density at a gas density monitoring position (PD) reaches a threshold. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a fuel cell system including a fuel cell that generates power upon receiving a reaction gas, and more particularly to an improvement in a gas leak determination method.

  For example, a fuel cell vehicle equipped with a fuel cell is known as a fuel cell system including a fuel cell that generates power upon receiving a supply of a reaction gas including a fuel gas (hydrogen gas) and an oxidizing gas (air). In this type of fuel cell vehicle, it is desirable to suppress the leakage of flammable fuel gas (hydrogen), and hydrogen gas leakage is detected.

  Conventionally, for example, when the electric load of a fuel cell is smaller than a threshold, the output current of the fuel cell is cut off, and a plurality of closed spaces are formed in the fuel gas circulation supply system including the fuel cell, and the pressure in each closed space A method for detecting whether or not a gas leak has occurred from a change has been proposed (see Patent Document 1).

  Also, when the vehicle speed is lower than the predetermined value, hydrogen leakage is detected by the hydrogen leak detector. When the vehicle speed is higher than the predetermined value, the theoretical value of the generated current of the fuel cell and the actual generated current value of the fuel cell are There has been proposed a method in which leakage of hydrogen is detected from the current consumption state indicating the correlation between the two (see Patent Document 2).

On the other hand, in order to quickly detect hydrogen leaks, a hydrogen collection part for collecting hydrogen lighter than air was formed in the upper part of the stack case of the fuel cell, and a hydrogen detection sensor was arranged in the hydrogen collection part. The thing is proposed (refer patent document 3).
JP 2003-308866 A JP 2004-139842 A JP 2002-367648 A

  Gas leaks at one gas leak assumption site can be detected by a flow sensor or a pressure sensor, but the gas leak amount that can be detected at the gas leak assumption site varies depending on the pressure of the gas piping and the size of the sensor measurement range. For this reason, the gas leak detection interval and the gas leak detection time are different for each assumed gas leak site and sensor. What is ultimately desired to be monitored is that, for example, the gas concentration at a predetermined position where an oxidation reaction can occur does not reach a predetermined threshold value.

  However, all of those described in Patent Documents 1 to 3 are required until the gas concentration at the gas concentration monitoring position at which the gas leakage amount and the gas concentration at the gas leakage assumption site are to be kept below the threshold value reaches the threshold value. The gas leak was not judged in relation to time. Therefore, when gas leak detection is performed by a plurality of sensors, the optimum detection time has not been set.

  And when detecting gas leaks at a plurality of gas leak assumption sites or detecting gas leaks at one gas leak assumption site by a plurality of sensors, simply assigning the same measurement time to each sensor For some sensors, a lot of gas leak detection time is allocated and the gas concentration at the gas concentration monitoring position exceeds the threshold, or for some sensors, gas leak detection is executed more frequently than necessary. It may reduce efficiency.

  That is, if the measurement time for the gas leak assumption portion is made too long compared to the detectable gas leak amount, the gas leak amount when the gas leak occurs increases. As a result, the gas concentration at the gas concentration monitoring position is reduced to an undesirable concentration. It will rise. On the other hand, if the measurement time for the estimated gas leak part is made too short compared to the detectable gas leak amount, the overall measurement time will be shortened, but even if a gas leak is detected, the gas concentration monitoring position at that time In this case, the gas concentration is considerably lower than the threshold value, and the gas leak is detected excessively.

  The present invention has been made in view of the problems of the prior art, and an object thereof is to set an appropriate gas leak measurement time for a detectable gas leak amount.

  In order to solve the above-described problems, a fuel cell system according to the present invention includes a fuel cell that generates power by receiving supply of a reaction gas, and a gas leak amount that can be detected at a predetermined gas leak assumption site, The gas leak measurement time is set based on a ratio to the elapsed time from when the gas leak occurs at the assumed gas leak portion until the gas concentration at the gas concentration monitoring position reaches the determination value.

  Further, the fuel cell system of the present invention is a fuel cell system having a fuel cell that generates power by receiving supply of a reaction gas, and a detectable gas leakage amount determined for each sensor that detects a gas leakage at a predetermined gas leakage assumed site; The gas leak measurement time is set based on a ratio to the elapsed time from when the gas leak occurs at the assumed gas leak portion until the gas concentration at the gas concentration monitoring position reaches a determination value.

  According to such a configuration, the amount of gas leakage that can be detected at the assumed portion of gas leakage, the amount of gas leakage that can be detected by the sensor, and the time from when the gas leakage occurs until the gas concentration at the gas concentration monitoring position reaches the judgment value. Since the relationship with the elapsed time is grasped, an appropriate gas leak measurement time that is neither too long nor too short with respect to the detectable gas leak amount can be set.

  That is, when the fuel gas leaks from any part of the region where the fuel gas circulates, the gas concentration of the leaked fuel gas from the time of gas leakage at the gas concentration monitoring position where the gas concentration is to be kept below the predetermined concentration Is a threshold value (for example, the time required to reach a threshold value that requires caution) depends on the distance between a gas leaking part (gas leaking expected part) and the gas concentration monitoring position.

  Paying attention to this point, the detectable gas leak amount Q at the gas leak assumption portion and the gas concentration at the gas concentration monitoring position from the time when the gas leak occurs at the gas leak assumption portion until the threshold value Cjdg is reached. Therefore, a certain relationship is established with the elapsed time T. Therefore, based on a certain relationship, the time T until the gas concentration at the gas concentration monitoring position reaches the threshold value Cjdg from the gas leak amount Q that can be detected at the assumed gas leak portion is obtained, and the obtained time By allocating the length to the measurement time of each part, it is possible to assign the measurement time with an appropriate time distribution as compared with the case where the same measurement time is uniformly assigned to each gas leakage assumed part and each sensor.

  The measurement of the amount of gas leakage by the “sensor” may be performed by detecting the gas pressure based on a known technique or by detecting the gas flow rate.

In configuring the fuel cell system, the following elements can be added.
Preferably, a sensor for detecting a gas leakage amount in each of a plurality of assumed gas leak sites, and a determination value in which the gas leak amount of each gas leak site assumed by the sensor is set for each gas leak site expected And a processing unit that executes a gas leak detection process for determining whether or not the gas leak is greater than the gas leak detection process. Execute continuously while changing the gas leak assumption part.

  According to such a configuration, when there are a plurality of gas leak assumption parts, the detectable gas leak amount differs for each gas leak assumption part, and the gas leak amount of each gas leak assumption part is set for each gas leak assumption part. When executing the gas leak detection process for determining whether or not it is greater than the determined determination value, the gas leak detection process is performed while changing the gas leak assumed part each time the time length allocated for each gas leak assumed part elapses. Since it performs continuously, the gas leak measurement time with respect to all the gas leak assumption parts can be set appropriately, without measuring time being too long or too short.

  Preferably, a plurality of sensors that respectively detect the amount of gas leakage at one assumed gas leak site, and whether each gas leak amount at the assumed gas leak site by detection of the sensor is greater than a determination value set for each sensor And a processing unit that executes a gas leak detection process for determining whether or not the gas leak detection process is continuously performed while changing the sensor each time the time allocated for the sensor elapses.

  According to such a configuration, when there are a plurality of sensors that measure gas leaks for one gas leak assumption site, the detectable gas leak amount differs for each sensor, and the gas leak amount detected by each sensor is different for each sensor. When executing the gas leak detection process for determining whether or not the determination value is greater than the determination value set for each time, the gas leak detection process is continuously performed while changing the assumed part of the gas leak every time the time length allocated for each sensor elapses. Therefore, the gas leak measurement time for all the sensors can be set appropriately without the measurement time being too long or too short.

  Preferably, when the sensor detects that the amount of gas leakage is larger than the determination value, the processing means performs a gas leakage process on the assumed gas leakage portion.

  According to such a configuration, when it is detected that the amount of gas leakage is greater than the determination value, gas leakage processing for the gas leakage assumption portion, for example, display processing for specifying the gas leakage assumption portion, or gas leakage By executing the display process or the alarm generation process to the effect that it has occurred, it is possible to identify the expected gas leak site or to notify that a gas leak has occurred.

  Preferably, the processing means sets the determination value at which the ratio between the gas leakage amount and the elapsed time is constant in a plurality of stages corresponding to combinations of at least one of the gas leakage amount and the elapsed time being different. In addition, an area indicating the presence or absence of an abnormality related to gas leakage is set corresponding to each stage, and each time the elapsed time elapses, which area the gas leakage amount based on the detection of the sensor belongs to Judging.

  According to such a configuration, since the determination value at which the ratio between the gas leakage amount and the elapsed time is the same is set in a plurality of stages corresponding to combinations of at least one of the gas leakage amount or the elapsed time, When the amount is large, an abnormality can be detected at a fast timing, and when the amount of gas leakage is small, erroneous detection can be prevented by determining the presence or absence of abnormality over time.

  According to the present invention, the measurement interval is set based on the ratio between the detectable gas leak amount and the elapsed time from when the gas leak occurs until the gas concentration at the gas concentration monitoring position reaches the determination value. An appropriate gas leak measurement time can be set with no excess or deficiency with respect to the detectable gas leak amount.

Next, a preferred embodiment of the present invention will be described.
(Embodiment 1)
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 the 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.

  In the fuel gas passage 40, a shutoff valve (original valve) 43 that controls the outflow of fuel gas from the fuel gas supply device 42, a pressure sensor 44 that detects the pressure of the fuel gas, and a fuel gas pressure in the circulation path 51 are adjusted. A regulating valve 45 and a shutoff valve 46 for controlling the supply of fuel gas to the fuel cell 20 are installed. Further, the fuel gas passage 40 is provided with a pressure sensor 44 for detecting a gas leak according to the present invention.

  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 provided with a backflow prevention valve 56 for preventing the backflow of the airflow toward the circulation channel 51 side. Further, the circulation channel 51 is provided with pressure sensors 58 and 59 for detecting gas leakage according to the present invention. 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 and then supplied to the fuel cell 20. 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), RAM, ROM, 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 according to the battery operating state, for example, the electric power load, and the rotation of the hydrogen pump 55 and the air compressor 75. The number is adjusted, and further, opening / closing control of various valves (valves) or adjustment of the valve opening is performed.

  At this time, when executing the gas leak detection process by the control unit 80, a flow path (a flow path including the fuel gas flow path 40, the circulation flow path 51, and the exhaust flow path 61 through which the fuel gas (hydrogen) of the reaction gas flows. The gas leak amount that can be detected is estimated in advance for each possible gas leak region that can be assumed to cause a gas leak. For example, in FIG. 2, it is illustrated that there are two assumed gas leakage sites P1 and P2.

  Here, the gas leak at the assumed site of gas leak is measured by a predetermined sensor (pressure sensor or flow rate sensor), but the minimum measurable gas leak amount is due to factors such as pipe internal pressure, sensor measurable range, pipe structure, etc. It often varies depending on. And this minimum gas leak amount may be determined for every gas leak assumption site | part by the cooperative relationship of a some sensor, and may be determined according to the characteristic of one sensor. In the former, the amount of gas leakage that can be detected is determined for each assumed portion of gas leakage, and in the latter, the amount of gas leakage that can be detected is determined for each sensor.

  In FIG. 2, a detectable gas leakage amount Q <b> 1 determined by various factors of the system is grasped at the leakage assumed site P <b> 1. In the assumed leakage portion P2, a detectable gas leakage amount Q2 mainly determined by the sensor S2 is grasped.

  Here, an appropriate gas leak measurement for determining a gas leak so that the gas concentration at a predetermined concentration monitoring position PD is equal to or lower than a predetermined threshold value (for example, determined based on the gas concentration at which an oxidation reaction or the like can occur). Think of time.

  In this case, when the same amount of gas leakage occurs in each of the gas leakage assumption portions P1 and P2, the elapsed time from when the gas leakage occurs until the gas concentration at the concentration monitoring position PD reaches the threshold value is assumed to be gas leakage. Depending on the positional relationship R1, R2 between the parts P1, P2 and the gas concentration monitoring position PD, when the distance R1> distance R2, the gas concentration at the gas concentration monitoring position PD is changed after the gas leakage is assumed at the gas leakage assumed part P1. The elapsed time until the threshold value is reached is longer than the elapsed time until the gas concentration at the gas concentration monitoring position PD reaches the threshold value after the gas leakage has occurred at the gas leakage estimated portion P2.

  Further, as described above, if the detectable gas leak amount Q1 at the leak potential portion P1 and the detectable gas leak amount Q2 at the leak potential portion P2 are different from each other, these gas leaks are measured at any measurement time interval. The problem is whether or not to detect.

  The inventor of the present application has a measurement time that does not cause the gas concentration at the gas concentration monitoring position PD in question to reach the threshold value Cjdg when a minimum amount of gas leakage that can be detected occurs at each gas leakage assumption site. Focusing on what is necessary, the elapsed time T until the gas concentration at the gas concentration monitoring position PD reaches the threshold value Cjg when the gas leakage of the detectable gas leakage amount Q occurs is a factor determining the measurement interval. I came up with it.

  That is, when a gas leak with a detectable gas leak flow rate Q1 occurs in the assumed leak site P1, the gas concentration at the gas concentration monitoring position PD changes as shown in FIG. Assume that the threshold value Cjdg is reached after elapse. In addition, when a gas leak with a detectable gas leak flow rate Q2 occurs in the assumed leak site P2, the gas concentration at the gas concentration monitoring position PD changes as shown in FIG. 3B, and time T2 has elapsed since the gas leak occurred. Assume that the threshold value Cjdg is reached later.

  When these characteristics are plotted with respect to the elapsed time T and the assumed gas leakage flow rate Q from when the gas leakage occurs at the gas concentration monitoring position until the gas concentration reaches the threshold value Cjdg, a curve as shown in FIG. 4 is obtained. In the present invention, the ratio between the gas leakage flow rate Q and the elapsed time T from when the gas leakage occurs at the gas concentration monitoring position until the gas concentration reaches the threshold value Cjdg is appropriate as a criterion for determining the gas leakage amount. Based on this recognition, an appropriate gas leak detection time is assigned to each assumed gas leak portion using this ratio.

  That is, from the relationship between the detectable gas leak amount Q at the gas leak assumption site and the time T until the gas concentration at the gas concentration monitoring position reaches the threshold value Cjdg from when gas leak occurred at the gas leak assumption site. Times T1 and T2 until the gas concentration at the gas concentration monitoring position PD reaches the threshold value Cjdg from the gas leakage amounts Q1 and Q2 that can be detected by the sensors S1 and S2 at the respective gas leakage assumption portions P1 and P2 are respectively set in advance. The time length (elapsed time) T1 and T2 obtained by each calculation is assigned to the measurement time (measurement interval) of each part P1 and P2.

  That is, if the gas leak amounts Q1 and Q2 that can be detected at the gas leak assumption portions P1 and P2 can be set, the gas leak at each gas leak assumption portion P1 and P2 is measured based on the gas flow rates Q1 and Q2. Since the time length required for the calculation is obtained by calculation, the time length obtained by the calculation is assigned to the measurement times of the parts P1 and P2 as times T1 and T2.

  Next, the gas leak detection process in the present embodiment will be described with reference to the flowchart of FIG. 5 and the time chart of FIG. In the present embodiment, examples of sensors that can detect gas leakage in the fuel gas supply system 4 include pressure sensors 44, 58, and 59. The pressure sensor 44 can detect a gas leak at an assumed gas leak portion between the regulating valve 45 and the shutoff valve 46. The pressure sensor 58 can detect a gas leak at an assumed gas leak portion between the shutoff valve 52 and the hydrogen pump 55. The pressure sensor 59 can detect a gas leak at the assumed gas leak portion between the hydrogen pump 55 and the backflow prevention valve 56 / purge valve 63. It is assumed that each of them is allocated, for example, as gas leakage assumption portions P1 to P3.

  When the gas leak detection process is started, the control unit 80 sets i to 1 in order to select the gas leak assumption part P1 among the plurality of gas leak assumption parts Pi set for the region through which the fuel gas flows ( Step S10). And based on the pressure detected in the pressure sensor 44, predetermined | prescribed gas leak detection is implemented about the gas leak assumption site | part P1 (step S11). Next, the timer is started, the elapsed time from the measurement start time is measured, and the gas concentration at the gas concentration monitoring position is determined with reference to the characteristics as shown in FIG. Is determined as a threshold value Cjdg (step S12), and it is determined whether or not the elapsed time from the measurement start time has passed the time T1 (step S13).

  Thereafter, the control unit 80 determines whether or not a gas leak has been detected on the condition that the elapsed time from the measurement start time has passed the time T1 (step S14), and if no gas leak has been detected. Therefore, i is assumed to be i + 1 (step S15), assuming that no gas leak has occurred in the gas leak assumption site P1, and the gas leak assumption site to be measured next is P2. Then, it is determined whether i = imax, i.e., whether i is the maximum number imax (here, 3) determined by the system (step S16). If i = imax is not satisfied (NO), steps S11 to S16 are repeated until i = imax. When i becomes imax, the processing in this routine is terminated.

  Specifically, when i is 2, 3,..., Imax, each time (time length) T2, T3,..., Timax allocated for each gas leakage assumption portion P2, P3,. In addition, measurement of the presence or absence of gas leakage is performed for each gas leakage assumption portion P2, P3,..., Pimax continuously while changing the gas leakage assumption portions P2, P3,.

  On the other hand, when it is determined in step S14 that a gas leak has been detected (YES), the control unit 80 has performed a gas leak process, for example, a display process for specifying a gas leak assumed part or a gas leak has occurred. The display process or the alarm generation process is executed (step S17), and the process in this routine is terminated. When a gas leak is detected, the control unit 80 may specify a gas leak assumption part or notify an operator or driver that a gas leak has occurred by executing a gas leak process. it can.

  According to this embodiment, the measurement time required to measure the gas leaks for all the assumed gas leak sites Pi is appropriately longer than when the same measurement time is uniformly assigned to each gas leak assumed site Pi. Can be allocated.

(Embodiment 2)
Next, another embodiment of the present invention will be described with reference to FIG. In the present embodiment, the determination value at which the ratio between the gas leakage amount and the time becomes constant is set in a plurality of stages corresponding to combinations of gas leakage amounts or at least one of the times, and each stage Correspondingly, a region indicating the presence or absence of abnormality related to gas leakage is set, and each time the time passes, it is determined which region the gas leakage amount based on the detection of the gas concentration sensor 101 belongs to. Other configurations are the same as those in the above embodiment.

  Specifically, in the present embodiment, the determination values Q1 / T1 and Q2 / T2 are set such that Q / T = C in which the relationship between the gas leakage amount Q and the time (determination timing) T indicates a ratio is constant. The gas leakage flow rate Q1 at time T1 and the gas leakage flow rate Q2 at time T2 are divided into three regions A1, A2, A3 divided by straight lines Q1 / T1 and Q2 / T2, respectively. The presence / absence of an abnormality related to gas leakage is determined according to which of the regions.

  In this case, information on the areas A1, A2, and A3 shown in FIG. 7 is set in the database of the control unit 80. For example, the region A1 is a region where the gas leakage amount Q is less than Q1 / T1, and is set as a region where it can be determined that there is no gas leakage and is in a normal state at time T1, and the region A2 is a gas leakage amount Q. Is a region that is greater than or equal to Q1 / T1 and less than Q2 / T1, and at time T1, it cannot be determined that there is no gas leakage and is in a normal state. Until time T2, gas leakage occurs and is in an abnormal state. Is set as a region that cannot be determined, and the region A3 is a region where the gas leakage amount Q is equal to or greater than Q2 / T1, and at time T1, gas leakage occurs and is set as a region that can be determined as being in an abnormal state.

  Here, when executing the gas leak detection process, the control unit 80 sets the gas leak flow rate Q to any one of the areas A1, A2, and A3 on the condition that the elapsed time from the measurement start time is the time T1. When the gas leak amount Q enters the region A1, it is determined that there is no gas leak and is in a normal state, and when the gas leak amount Q enters the region A2, the gas leaks until time T2. It is decided to wait for the determination of whether there is an abnormality related to leakage, and when the gas leakage amount Q enters the region A3, it is determined that a gas leakage has occurred and is in an abnormal state.

  Next, when it is determined at time T1 that the gas leakage amount Q enters the region A2, the control unit 80 determines whether the gas leakage amount Q enters the region A1 or A2 at the time T2. When the gas leak amount Q enters the region A1, it is determined that there is no gas leak and is in a normal state. When the gas leak amount Q enters the region A2, the determination of whether there is an abnormality related to the gas leak is indefinite. Alternatively, until the time T3, the determination of the presence / absence of an abnormality related to gas leakage is awaited. Thereafter, the control unit 80 repeats the determination as to whether the gas leakage flow rate Q enters any of the regions A1 and A2 at the times T3, T4,..., Tn as in the case of the time T2.

  According to the present embodiment, since the determination value at which the ratio Q / T between the gas leakage amount Q and the time T is the same is set in two stages of Q1 / T1 and Q2 / T2, when the gas leakage amount is large Abnormalities can be detected at a fast timing, and when the amount of gas leakage is small, erroneous detection can be prevented by determining the presence or absence of abnormality over time.

1 is a system configuration diagram of a fuel cell system showing an embodiment of the present invention. It is a figure for demonstrating the positional relationship and gas concentration of a gas leak assumption site | part and a gas concentration monitoring position. (A) Characteristic diagram of gas leak flow rate when the distance between the assumed gas leak portion and the gas concentration monitoring position is long, (b) Characteristic of gas leak flow rate when the distance between the assumed gas leak portion and the gas concentration monitoring position is short FIG. It is a characteristic view of the gas leakage flow rate determined from the relationship between gas concentration and time. It is a flowchart for demonstrating the gas leak detection process by a control part. It is a time chart for demonstrating the gas leak detection process by a control part. It is a figure for demonstrating the structure of the determination area | region when the determination reference value determined from the relationship between determination timing and a gas leak flow rate is divided and set in two steps.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 Fuel cell system, 20 Fuel cell, 40 Fuel gas flow path, 44, 58, 59 Pressure sensor, 55 Hydrogen pump, 71 Oxidation gas flow path, 80 Control part

Claims (6)

In a fuel cell system having a fuel cell that generates power upon receiving a supply of a reaction gas,
Based on the ratio between the detectable gas leak amount at a predetermined gas leak assumption site and the elapsed time from when the gas leak occurred at the gas leak assumption site until the gas concentration at the gas concentration monitoring position reaches the judgment value A fuel cell system characterized by setting a gas leak measurement time. In a fuel cell system having a fuel cell that generates power upon receiving a supply of a reaction gas,
Detectable gas leak amount determined for each sensor that detects gas leak at a predetermined gas leak assumption site, and from when gas leak occurs at the gas leak assumption site until the gas concentration at the gas concentration monitoring position reaches a judgment value A fuel cell system, wherein a gas leak measurement time is set based on a ratio to the elapsed time. A sensor for detecting the amount of gas leakage in each of the plurality of assumed gas leakage sites;
Processing means for performing a gas leak detection process to determine whether or not the amount of gas leak at each gas leak assumption site detected by the sensor is greater than the determination value set for each gas leak assumption site. ,
The said processing means performs the said gas leak detection process continuously, changing the said gas leak assumption site | part, whenever the time allotted about each said gas leak assumption site | part passes. Or the fuel cell system of 2. A plurality of sensors for respectively detecting the amount of gas leakage at one gas leakage assumption site;
Processing means for performing a gas leak detection process as to whether or not each of the gas leak amounts of the gas leak assumption portion detected by the sensor is greater than the determination value set for each sensor,
3. The fuel cell according to claim 1, wherein the processing unit continuously executes the gas leak detection process while changing the sensor every time when the time allocated for the sensor elapses. system. The processing means includes
5. The fuel cell system according to claim 3, wherein when the sensor detects that the amount of gas leakage is greater than the determination value, a gas leakage process is performed on the assumed portion of gas leakage. . The processing means includes
The determination value at which the ratio between the gas leakage amount and the elapsed time is constant is set in a plurality of stages corresponding to combinations of at least one of the gas leakage amount or the elapsed time,
Set an area to indicate whether there is an abnormality related to gas leakage corresponding to each stage,
5. The fuel cell system according to claim 3, wherein each time the elapsed time elapses, it is determined whether the gas leakage amount based on the detection of the sensor belongs to which region.

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