JP2009037884A - Fuel cell system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel cell system, capable of securely and safely detecting leak of anode gas. <P>SOLUTION: The fuel cell system 1 comprises a fuel cell 10 to generate power by reaction of anode gas with cathode gas, an anode gas passage in which anode gas supplied to the fuel cell 10 and anode gas discharged from the fuel cell 10 flow, a pressure sensor 61 to detect pressure of the anode gas in the anode gas passage, a seal control part 32 to seal a seal part 70 in at least the anode gas passage including the fuel cell 10 after supply of the anode gas to the fuel cell 10 is stopped, a pressure change monitor part 33 to monitor pressure change of the anode gas due to consumption of the anode gas detected by the pressure sensor 61 concerning the seal part 70, and a gas leak determination part 35 to determine whether or not the anode gas is leaking from the seal part 70 based on the result of monitoring of the pressure of the anode gas by the pressure change monitor part 33. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a fuel cell system. In detail, it is related with the fuel cell system mounted in a motor vehicle.

  In recent years, fuel cell systems have attracted attention as a new power source for automobiles. The fuel cell system includes, for example, a fuel cell that generates power by chemically reacting a reaction gas, a reaction gas supply device that supplies the reaction gas to the fuel cell via a reaction gas flow path, and a control that controls the reaction gas supply device. An apparatus.

  When a fuel cell supplies an anode gas (hydrogen gas) as a reaction gas to an anode electrode (anode) and supplies a cathode gas (air) as a reaction gas to a cathode electrode (cathode), the fuel cell generates electricity by an electrochemical reaction.

  Here, an anode gas supply channel is connected to the fuel cell, and the anode gas is supplied to the fuel cell through the anode gas supply channel. An anode gas discharge channel is connected to the fuel cell, and the anode gas is discharged from the fuel cell through the anode gas discharge channel.

  By the way, the gas flow paths such as the anode gas supply flow path and the anode gas discharge flow path are composed of a plurality of pipes and valves. Therefore, there is a possibility that the anode gas leaks from the gaps between the flanges of these pipes or from the valves. is there.

In order to solve this problem, a method has been proposed in which anode gas is supplied to pressurize the inside of the gas flow path, and based on the flow rate of the anode gas at the time of pressurization, it is determined whether or not the anode gas is leaking. (See Patent Document 1).
Specifically, the anode gas is supplied to pressurize the inside of the gas flow path, and the flow rate of the anode gas during the pressurization is measured. Also, a reference flow rate is calculated based on changes in the pressure, temperature, etc. of the anode gas in the gas flow path. Then, a difference between the measured flow rate and the reference flow rate is obtained, and when the difference is equal to or greater than a predetermined value, it is determined that the anode gas is leaking.

According to this proposal, it is possible to reliably detect the leak of the anode gas, maintain the fuel efficiency, and further ensure safety.
JP 2006-278088 A

  However, in the method of Patent Document 1, since the inside of the gas flow path is pressurized, when the anode gas actually leaks, there is a possibility of promoting the leakage of the anode gas.

  An object of this invention is to provide the fuel cell system which can detect the leak of anode gas reliably and safely.

  The fuel cell system of the present invention is a fuel cell (for example, a fuel cell 10 described later) that generates electricity by reacting an anode gas and a cathode gas, an anode gas supplied to the fuel cell, and an exhaust gas from the fuel cell. An anode gas flow path (for example, an anode gas supply path 43, an anode gas discharge path 44, and an anode gas recirculation path 45, which will be described later) through which the anode gas flows, and pressure detection for detecting the pressure of the anode gas in the anode gas flow path Gas passage sealing for sealing at least a portion of the anode gas passage including the fuel cell after supply of the anode gas to the fuel cell is stopped. Means (for example, a sealing control unit 32 described later) and a portion sealed by the gas flow path sealing unit, by the pressure detection unit. Based on the pressure transition monitoring means (for example, the pressure transition monitoring unit 33) for monitoring the transition of the pressure of the anode gas due to the detected anode gas consumption, and the monitoring result of the pressure of the anode gas by the gas pressure transition monitoring means, the gas It has sealing part gas leak determination means (for example, the gas leak determination part 35 mentioned later) which determines whether anode gas is leaking from the part sealed by the flow-path sealing means, It is characterized by the above-mentioned.

  According to the present invention, after the supply of the anode gas to the fuel cell is stopped, at least a portion including the fuel cell in the anode gas channel is sealed. And about the sealed part, transition of the pressure of the anode gas by anode gas consumption is monitored. Based on the monitoring result of the pressure of the anode gas, it is determined whether or not the anode gas leaks from the sealed portion.

  When the portion including the fuel cell in the anode gas flow path is sealed, the anode gas remaining in the sealed portion is consumed, and the fuel cell generates power. As a result, the pressure in the sealed portion in the anode gas flow path is reduced to a negative pressure with respect to the external pressure. Therefore, since the anode gas does not leak to the outside from the sealed portion in the anode gas flow path, the leakage of the anode gas can be detected reliably and safely.

  In this case, the fuel cell system includes gas leak estimation means (for example, a gas leak estimation unit 31 described later) for estimating whether or not the anode gas is leaking from the anode gas flow path during power generation of the fuel cell. A portion sealed by the gas flow path sealing means by the sealed portion gas leak determination means when the gas leak estimation means estimates that the anode gas is leaking from the anode gas flow path; It is preferable to determine whether or not the anode gas is leaking from.

  Conventionally, during the power generation of the fuel cell, for example, when anode gas is detected by an anode gas sensor, leakage of the anode gas is detected. Further, the power generation amount of the fuel cell is measured using a current sensor or a voltage sensor, and when this power generation amount is not the power generation amount commensurate with the supply amount of the anode gas, the leakage of the anode gas is detected.

  However, when a leak of the anode gas is detected based on the detection of the anode gas by the anode gas sensor, there is a possibility that electrical noise generated by the anode gas sensor is erroneously detected as a leak of the anode gas. In addition, when anode gas leakage is detected based on the fact that the amount of power generation commensurate with the supply amount of anode gas cannot be obtained, there is a possibility that the power generation amount has decreased due to a factor different from the anode gas leakage. There is a risk of false detection.

  Therefore, according to the present invention, when anode gas leakage is detected by the gas leakage estimation means using an anode gas sensor, current sensor, voltage sensor, or the like, whether the anode gas is leaked by the gas leakage determination means described above. Judged whether or not. Therefore, it can be accurately determined whether or not the detection of the leak of the anode gas by the gas leak estimation means is correct.

  Further, only when the leakage of anode gas is detected by the gas leakage estimation means as described above, it is determined whether or not the anode gas is leaked by the gas leakage determination means. It is not operated and power consumption can be reduced.

  In the fuel cell system of the present invention, after sealing by the gas flow path sealing means, the sealed portion of the anode gas is naturally consumed by the reaction of the fuel cell, and the sealed portion gas leak determination means is naturally consumed. When it is determined that the anode gas amount is equal to or greater than a predetermined amount, it is determined whether or not the anode gas is leaking.

  According to the present invention, since the anode gas is naturally consumed in the fuel cell, a special device is used to reduce the pressure of the sealed portion in the anode gas passage when determining whether or not the anode gas is leaking. Do not need.

  In the fuel cell system of the present invention, after sealing by the gas flow path sealing means, the sealed portion of the anode gas is consumed by forced power generation of the fuel cell (for example, carried out by a gas consumption control unit 36 described later). The sealing portion gas leak determination means determines whether or not the anode gas is leaked when it is determined that the consumed anode gas amount is a predetermined amount or more.

  According to this invention, since the anode gas is consumed by forced power generation of the fuel cell, that is, discharge, it can be determined whether or not the anode gas leaks more quickly than natural consumption.

  According to the present invention, when the portion including the fuel cell in the anode gas channel is sealed, the anode gas remaining in the anode gas channel is consumed, and the fuel cell generates power. As a result, the pressure in the sealed portion in the anode gas flow path is reduced to a negative pressure with respect to the external pressure. Therefore, since the anode gas does not leak to the outside from the anode gas flow path, the leakage of the anode gas can be detected reliably and safely.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
<First Embodiment>
FIG. 1 is a block diagram of a fuel cell system 1 according to the first embodiment of the present invention.
The fuel cell system 1 includes a fuel cell 10 that generates power by reacting a reaction gas, a supply device 20 that supplies the fuel cell 10 with an anode gas and a cathode gas as a reaction gas, and the fuel cell 10 and the supply device 20. And a control device 30 for controlling.

  The supply device 20 processes a cathode gas pump 21 that supplies a cathode gas to the cathode electrode side of the fuel cell 10, an anode gas tank 22 and an ejector 23 that supply an anode gas to the anode electrode side, and a gas discharged from the fuel cell 10. And a diluter 24.

  The cathode gas pump 21 is connected to the cathode electrode side of the fuel cell 10 via a cathode gas supply path 41.

  A cathode gas discharge path 42 is connected to the cathode electrode side of the fuel cell 10, and the cathode gas discharge path 42 discharges the cathode gas used in the fuel cell 10. The above-described diluter 24 is provided in the middle of the cathode gas discharge path 42, and a back pressure valve 421 is further provided on the fuel cell 10 side of the diluter 24 in the cathode gas discharge path 42.

  The anode gas tank 22 is connected to the anode electrode side of the fuel cell 10 via an anode gas supply path 43 as an anode gas flow path. The above-described ejector 23 is provided in the anode gas supply path 43. The anode gas tank 22 is provided with an in-tank electromagnetic valve 431, and a secondary shut-off valve 432 is provided between the anode gas tank 22 and the ejector 23 in the anode gas supply path 43.

  An anode gas discharge path 44 as an anode gas flow path is connected to the anode electrode side of the fuel cell 10, and the anode gas discharge path 44 is connected to the diluter 24. A purge valve 441 is provided on the tip side of the anode gas discharge path 44. Further, in the anode gas discharge path 44, the anode gas discharge path 44 is branched on the fuel cell side from the purge valve 441 to become an anode gas recirculation path 45 as an anode gas flow path. Are connected to the ejector 23.

  A pressure sensor 61 is provided between the anode gas discharge path 44 and the branch point of the fuel cell 10 and the anode gas recirculation path 45 as pressure detection means for measuring the pressure of the internal anode gas.

  A purge valve 441 is provided in the anode gas discharge path 44. By opening the purge valve 441, the anode gas in the anode gas supply path 43, the anode gas discharge path 44, and the anode gas recirculation path 45 is merged with the cathode gas in the cathode gas discharge path 42 in the diluter 24. .

  The ejector 23 collects the anode gas discharged to the anode gas discharge path 44 through the anode gas reflux path 45 and returns it to the anode gas supply path 43.

  Further, the fuel cell system 1 is provided with an anode gas sensor 64 that detects the anode gas outside the anode gas supply path 43, the anode gas discharge path 44, and the anode gas recirculation path 45.

The fuel cell 10 is provided with a current sensor 62 that measures a current value generated by the fuel cell 10 and a voltage sensor 63 that measures a voltage value at that time.
The fuel cell 10 is connected to an auxiliary device 50 that is driven by the electric power generated by the fuel cell 10.

  The in-tank electromagnetic valve 431, the secondary shutoff valve 432, and the purge valve 441 are controlled by the control device 30. Further, the pressure sensor 61, the current sensor 62, the voltage sensor 63, and the anode gas sensor 64 are connected to the control device 30.

FIG. 2 is a block diagram of the control device 30.
The control device 30 includes a gas leak estimation unit 31 as a gas leak estimation unit, a sealing control unit 32 as a gas flow path sealing unit, a pressure transition monitoring unit 33 as a pressure transition monitoring unit, and a gas consumption calculation unit 34. And a gas leak determination unit 35 as a sealed partial gas leak determination means.

  When the anode gas sensor 64 detects anode gas during power generation of the fuel cell 10, the gas leak estimation unit 31 leaks anode gas from the anode gas supply path 43, anode gas discharge path 44, and anode gas recirculation path 45. It is estimated that

  The gas leak estimation unit 31 estimates that the anode gas is leaked when the anode gas is detected by the anode gas sensor 64, but the present invention is not limited to this. That is, the power generation amount of the fuel cell 10 is measured by the current sensor 62 and the voltage sensor 63, and it may be estimated that the anode gas is leaking when the power generation amount is not the power generation amount commensurate with the supply amount of the anode gas.

  The sealing controller 32 estimates that the anode gas is leaking from the anode gas supply path 43, the anode gas discharge path 44, and the anode gas recirculation path 45 by the gas leak estimation section 31, and the anode gas to the fuel cell 10. Is closed, the in-tank electromagnetic valve 431 and the purge valve 441 are closed to seal the anode gas supply path 43, the anode gas discharge path 44, and the anode gas recirculation path 45 including the fuel cell 10. Hereinafter, the portion sealed by the in-tank electromagnetic valve 431 and the purge valve 441 is referred to as a sealed portion 70.

  The sealing control unit 32 closes the in-tank electromagnetic valve 431 and the purge valve 441. However, the present invention is not limited to this, and the secondary shutoff valve 432 and the purge valve 441 may be closed.

  Although it is estimated that the anode gas is leaking and the supply of the anode gas to the fuel cell 10 is stopped, the sealing control unit 32 is operated. When it is estimated that the anode gas is leaking, the ignition may be immediately turned off and the supply of the anode gas to the fuel cell 10 may be stopped.

  The pressure transition monitoring unit 33 receives the pressure value of the anode gas detected by the pressure sensor 61 for the sealed portion 70 and monitors the transition.

  The gas consumption calculation unit 34 calculates the amount of natural consumption of anode gas in the fuel cell 10 after the sealing portion 70 is sealed by the sealing control unit 32, and determines whether or not a predetermined amount of anode gas has been consumed. Determine. Specifically, the calculation is based on the consumption rate of the anode gas due to natural consumption and the elapsed time.

  In addition, although the gas consumption calculation part 34 calculated the amount by which the anode gas was consumed in the fuel cell 10 based on the consumption speed of anode gas by natural consumption, and elapsed time, it is not restricted to this. That is, it may be calculated based on the integrated value of the power generation measured by the current sensor 62 and the voltage sensor 63.

  When the gas consumption calculation unit 34 determines that a predetermined amount or more of the anode gas has been consumed, the gas leak determination unit 35 monitors the pressure transition of the anode gas in the sealed portion 70 monitored by the pressure transition monitoring unit 33. Based on the result, it is determined whether the anode gas is leaking from the sealed portion 70 according to FIG.

FIG. 3 is a diagram showing the relationship between the time elapsed after the sealed portion 70 is sealed and the pressure of the anode gas in the sealed portion 70 with the passage of time.
When the anode gas does not leak from the sealed portion 70, the fuel cell 10 reacts in a sealed state, so that the anode gas in the sealed portion 70 is consumed, and the pressure of the anode gas decreases with time.
On the other hand, when the anode gas leaks from the sealed portion 70, the outside air is drawn from the portion where the anode gas leaks, and therefore the pressure gradually decreases, compared with the case where the anode gas does not leak from the sealed portion 70. The decline of the

  According to FIG. 3, the gas leak determination unit 35 assumes that the time when the sealed portion 70 is sealed is t0. At time t1 when a predetermined time has elapsed from this time t0, if the pressure decrease amount is equal to or less than the determination threshold, the anode gas is If it is leaking and the pressure reduction amount exceeds the determination threshold, it is determined that the anode gas is not leaking.

FIG. 4 is a flowchart showing the operation of the fuel cell system 1.
In S1, it is determined whether the ignition is ON. If this determination is NO, the process returns to S1, and if this determination is YES, the process proceeds to S2.

In S2, since the ignition of the fuel cell system 1 is turned on and the supply of anode gas to the fuel cell 10 has started, the gas leak estimation unit 31 estimates whether or not the anode gas is leaking. Specifically, it is determined whether or not the detected amount of anode gas is a predetermined amount or more.
If this determination is YES, since a predetermined amount or more of the anode gas has been detected, the process proceeds to S3, and the gas leak flag is set to 1 in S3. On the other hand, if this determination is NO, the anode gas of a predetermined amount or more has not been detected, so the routine proceeds to S4, where the gas leak flag is set to 0.

  In S5, it is determined whether or not the ignition is OFF. If this determination is NO, the process returns to S2, and if this determination is YES, the process proceeds to S6. Thus, the gas leak estimation part 31 repeats the process of S2-S5 until the ignition of the fuel cell system 1 is turned off.

  In S6, it is determined whether or not the gas leak flag is 1. If this determination is YES, the process proceeds to S7, and if this determination is NO, it is determined that the anode gas is not leaking, and the process is terminated.

  In S <b> 7, the sealing portion 70 is sealed by the sealing control unit 32, and subsequently, in S <b> 8, the pressure transition monitoring unit 33 measures the pressure P <b> 1 of the anode gas in the sealing portion 70.

  In S9, the gas consumption calculation unit 34 determines whether or not a predetermined amount or more of the anode gas has been consumed. If this determination is YES, the process moves to S10, and if this determination is NO, the process returns to S9.

  In S10, since a predetermined amount of anode gas is consumed in the fuel cell 10, the pressure transition monitoring unit 33 again measures the pressure P2 of the anode gas in the sealed portion 70.

  In S11, the gas leak determination unit 35 determines whether or not the difference between the pressure P1 and the pressure P2 is equal to or less than a determination threshold value. If this determination is YES, the process moves to S12 and it is determined that the anode gas is leaking. On the other hand, if this determination is NO, the process moves to S13, where it is determined that the anode gas is not leaking.

According to this embodiment, there are the following effects.
(1) After the supply of the anode gas to the fuel cell 10 is stopped, the sealing portion 70 is sealed. Then, regarding the sealed portion 70, the transition of the pressure of the anode gas due to the consumption of the anode gas is monitored. Based on the monitoring result of the pressure of the anode gas, it is determined whether or not the anode gas leaks from the sealed portion 70.
When the sealing portion 70 is sealed, the anode gas remaining in the sealing portion 70 is consumed, and the fuel cell 10 generates power. As a result, the pressure in the sealed portion 70 decreases and becomes negative with respect to the external pressure. Therefore, since the anode gas does not leak to the outside from the sealed portion 70, the leak of the anode gas can be detected reliably and safely.

  (2) Whether or not the anode gas is leaked by the gas leak determination unit 35 when the leak of the anode gas is detected by the gas leak estimation unit 31 using the anode gas sensor 64, the current sensor 62, the voltage sensor 63, etc. Was judged. Therefore, it can be accurately determined whether or not the detection of the leak of the anode gas by the gas leak estimation unit 31 is correct.

  Further, only when the gas leakage estimation unit 31 detects the leakage of the anode gas, the gas leakage determination unit 35 determines whether or not the anode gas is leaking. Therefore, the gas leakage determination unit 35 is operated unconditionally. No, power consumption can be reduced.

  (3) Since the anode gas is naturally consumed in the fuel cell 10, no special device is required to reduce the pressure of the sealed portion 70 when determining whether or not the anode gas is leaking.

Second Embodiment
In the present embodiment, the anode gas in the sealed portion 70 is not naturally consumed by the fuel cell 10 but the anode gas in the sealed portion 70 is forcibly consumed by forcibly generating power in the fuel cell 10 in the first embodiment. Different from form.

FIG. 5 is a block diagram of the control device 30A.
Specifically, the control device 30A includes a gas consumption control unit 36 instead of the gas consumption calculation unit 34 in the first embodiment.

  The gas consumption controller 36 drives the auxiliary machine 50 after the sealing portion 70 is sealed by the sealing controller 32. Thereby, the fuel cell 10 is forcibly generated, that is, discharged, and the anode gas in the sealed portion 70 is consumed. The gas consumption control unit 36 calculates the amount of anode gas consumed by the fuel cell 10 and determines whether or not a predetermined amount of anode gas has been consumed. Specifically, the calculation is based on the consumption rate of the anode gas and the elapsed time.

FIG. 6 is a flowchart showing the operation of the fuel cell system 1.
In the present embodiment, the processes of S21 to S23 are performed instead of the process of S9 in the flowchart of the first embodiment shown in FIG.

  In S21, the gas consumption control unit 36 starts the forced power generation of the fuel cell 10 and starts to forcibly consume the anode gas in the sealed portion 70, and then proceeds to S22.

  In S22, the gas consumption control unit 36 determines whether or not a predetermined amount or more of the anode gas has been consumed. If this determination is YES, the process moves to S23, and if this determination is NO, the process returns to S22.

  In S23, since a predetermined amount of anode gas is consumed in the fuel cell 10, the forced power generation of the fuel cell 10 by the gas consumption control unit 36 is terminated, and the process proceeds to S10.

According to this embodiment, there are the following effects.
(4) Since the anode gas is consumed by forced power generation, that is, discharge of the fuel cell 10, it can be determined whether or not the anode gas leaks more quickly than natural consumption.

  It should be noted that the present invention is not limited to the above-described embodiment, and modifications, improvements, etc. within a scope that can achieve the object of the present invention are included in the present invention.

1 is a block diagram of a fuel cell system according to a first embodiment of the present invention. It is a block diagram of the control apparatus of the fuel cell system which concerns on the said embodiment. It is a figure which shows the relationship between the time passage after the sealing part which concerns on the said embodiment was sealed, and the pressure of the anode gas of a sealing part. It is a flowchart which shows operation | movement of the fuel cell system which concerns on the said embodiment. It is a block diagram of the control apparatus of the fuel cell system which concerns on 2nd Embodiment of this invention. It is a flowchart which shows operation | movement of the fuel cell system which concerns on the said embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Fuel cell system 10 Fuel cell 30, 30A Control apparatus 31 Gas leak estimation part (gas leak estimation means)
32 Sealing control part (gas flow path sealing means)
33 Pressure change monitoring part (Pressure change monitoring means)
34 Gas consumption calculation part 35 Gas leak judgment part (sealed partial gas leak judgment means)
36 Gas Consumption Control Unit 43 Anode Gas Supply Channel (Anode Gas Channel)
44 Anode gas discharge passage (anode gas passage)
45 Anode gas recirculation path (anode gas flow path)
70 Sealing part

Claims (4)

A fuel cell that generates electricity by reacting anode gas and cathode gas;
An anode gas flow path through which an anode gas supplied to the fuel cell and an anode gas discharged from the fuel cell flow;
A fuel cell system having pressure detection means for detecting the pressure of the anode gas in the anode gas flow path,
A gas flow path sealing means for sealing at least a portion of the anode gas flow path including the fuel cell after the supply of the anode gas to the fuel cell is stopped;
Pressure transition monitoring means for monitoring the transition of the pressure of the anode gas due to consumption of the anode gas detected by the pressure detection means for the portion sealed by the gas flow path sealing means;
Sealing portion gas leakage determination means for determining whether or not anode gas is leaking from the portion sealed by the gas flow path sealing means based on the monitoring result of the pressure of the anode gas by the pressure transition monitoring means. Fuel cell system. A gas leak estimation means for estimating whether or not anode gas is leaking from the anode gas flow path during power generation of the fuel cell;
When it is estimated by the gas leak estimation means that the anode gas is leaking from the anode gas flow path, the anode gas is discharged from the portion sealed by the gas flow path sealing means by the sealed portion gas leak determination means. The fuel cell system according to claim 1, wherein it is determined whether or not there is a leak. After sealing by the gas flow path sealing means, the sealed portion of the anode gas is naturally consumed by the reaction of the fuel cell,
The said sealed partial gas leak judging means judges whether or not the anode gas is leaking when it is judged that the amount of the naturally consumed anode gas is a predetermined amount or more. Item 3. The fuel cell system according to Item 2. After sealing by the gas flow path sealing means, the anode gas in the sealed part is consumed by forced power generation of the fuel cell,
2. The sealed portion gas leak judging means judges whether or not the anode gas is leaked when it is judged that the consumed anode gas amount is a predetermined amount or more. 3. The fuel cell system according to 2.

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