JP2009277670A - Onboard fuel cell system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an onboard fuel cell system capable of securing high safety. <P>SOLUTION: Hydrogen gas discharged from a shut valve 414 is sent into an oxygen off-gas discharge flow passage 503 by passing through a discharge flow passage 407, and is diluted by being mixed with oxygen off-gas flowing in the oxygen off-gas discharge flow passage 503 in a mixing part 411. The gas mixed by the mixing part 411 flows in a combustor 510 via a gas-liquid separator 508. The combustor 510 has a platinum catalyst 512, and further reduces the concentration of hydrogen included in the mixed gas by reacting the hydrogen included in the mixed gas with oxygen by combustion. The mixed gas reduced in the hydrogen concentration by the combustor 510 is discharged in the atmosphere. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an in-vehicle fuel cell system suitable for mounting on a vehicle such as an automobile, and a hydrogen off-gas discharge method for discharging hydrogen off-gas.

  A fuel cell that generates electric power upon receiving supply of hydrogen gas from a high-pressure hydrogen gas tank or a hydrogen storage alloy tank is highly promising as a power source for electric vehicles and the like because of its high energy efficiency.

  By the way, when such a fuel cell is used as a power source of a vehicle, not only the fuel cell but also a hydrogen gas supply source such as the above-described high-pressure hydrogen gas tank or hydrogen storage alloy tank, and the hydrogen gas supply source to the fuel cell are used. It is necessary to mount a fuel cell system including a hydrogen gas passage for feeding hydrogen gas on a vehicle.

  When a fuel cell system is mounted on a vehicle, since hydrogen gas with high flammability is handled, sufficient consideration is necessary for handling. However, it has not been sufficient to consider the hydrogen off-gas used for power generation in the fuel cell. In other words, the hydrogen off-gas may contain unconsumed hydrogen but is actually released into the atmosphere as it is.

In view of this situation, the following new issues were found and the solution was made.
Since hydrogen-containing gas is flammable, hydrogen off-gas is generated when the situation in which the hydrogen concentration in the gas released into the atmosphere increases and the situation in which there is a potential ignition source near the gas outlet. There is a risk of ignition.

  Accordingly, an object of the present invention is to provide an in-vehicle fuel cell system and a hydrogen off-gas discharge method capable of solving the above-described problems and discharging a hydrogen off-gas to the atmosphere with a sufficiently low hydrogen concentration.

In order to achieve at least a part of the above object, a first in-vehicle fuel cell system of the present invention includes:
In-vehicle fuel installed in a vehicle that is supplied with hydrogen gas and oxidant gas, and that uses these hydrogen gas and oxidant gas to generate electric power and has a fuel cell that discharges used hydrogen off-gas and oxygen off-gas. A battery system,
A first flow path connected to a hydrogen off-gas discharge port of the fuel cell and flowing the discharged hydrogen off-gas;
A second flow path connected to the oxygen off-gas discharge port of the fuel cell and flowing the discharged oxygen off-gas;
A mixing section that connects the first flow path and the second flow path and mixes the discharged hydrogen off-gas with the discharged oxygen off-gas;
A third flow path connected to the mixing section, for flowing the mixed gas and discharging it to the atmosphere;
It is a summary to provide.

Further, the hydrogen gas discharging method of the present invention is a fuel cell that receives supply of hydrogen gas and oxidizing gas, generates electric power using these hydrogen gas and oxidizing gas, and discharges used hydrogen off-gas and oxygen off-gas. In the hydrogen off-gas discharge method for discharging the hydrogen off-gas discharged into the atmosphere,
(A) mixing the hydrogen offgas discharged from the fuel cell with the discharged oxygen offgas;
(B) discharging the mixed gas into the atmosphere;
It is a summary to provide.

  Thus, in the on-vehicle fuel cell system or the hydrogen gas discharging method described above, the hydrogen off gas discharged from the fuel cell is mixed with the oxygen off gas discharged similarly. Since the oxygen off-gas is a nitrogen-rich gas, the hydrogen off-gas can be diluted by the above gas mixing, and the concentration of hydrogen contained in the mixed gas can be reduced. Therefore, after reducing the hydrogen concentration to a sufficiently low concentration, the mixed gas can be discharged into the atmosphere. As a result, it is preferable that the hydrogen off-gas is not inadvertently released into the atmosphere with a high hydrogen concentration.

The first vehicle-mounted fuel cell system of the present invention having the above configuration can take various aspects. First of all,
The mixing section,
An oxygen off-gas branch introduction flow channel that branches off from the second flow channel and introduces the oxygen off-gas by diverting from the second flow channel;
The oxygen off-gas branch introduction flow path and the first flow path are connected to each other, and the hydrogen off-gas and the oxygen off-gas are mixed, and then a mixing chamber whose volume is expanded to flow to the third flow path is provided. ,
The second flow path,
The oxygen off-gas branch introduction flow channel may join the third flow channel downstream from the branch point.

In the hydrogen gas discharge method of the present invention,
The step (a)
Introducing the hydrogen offgas discharged from the fuel cell from the first flow path through which the offgas flows into a mixing chamber having an enlarged volume (a1);
Introducing the oxygen off-gas discharged from the fuel cell into the mixing chamber from a branch channel branched from a second channel through which the off-gas flows;
Discharging the gas mixed in the mixing chamber to a third flow path connected to the mixing chamber,
The step (b)
The second flow path may include a step of joining the second flow path to the third flow path and discharging the gas to the atmosphere downstream from the branching point of the branch flow path. .

  In this case, in the mixing chamber, the hydrogen off-gas and the oxygen off-gas are efficiently mixed based on the expansion of the volume, which makes it possible to reliably dilute the hydrogen off-gas and lower the hydrogen concentration, which is preferable. In this case, the second channel may have a muffler between the branch point of the oxygen off-gas branch introduction channel and the junction point to the third channel. In this way, a pressure difference occurs in the flow path before and after the muffler due to the pressure loss that occurs in the muffler, so that the oxygen off gas can be reliably introduced into the mixing chamber via the oxygen off gas branch introduction flow path. For this reason, oxygen off-gas can be introduced without using special equipment, which is preferable from the viewpoint of simplification of equipment configuration and control and from the viewpoint of cost reduction. In addition, since gas mixing is performed in the mixing chamber with an increased volume, it is preferable from the viewpoint of noise reduction when the gas passes.

  And a catalyst reaction unit arranged in the third flow path and reacting hydrogen and oxygen contained in the mixed gas with a catalyst to reduce a hydrogen concentration in the gas. preferable.

In the hydrogen off-gas discharge method of the present invention, the step (b)
Reacting hydrogen and oxygen contained in the mixed gas with a catalyst to reduce the hydrogen concentration in the gas;
Discharging the gas with reduced hydrogen concentration into the atmosphere;
It is preferable to contain.

  In this way, hydrogen and oxygen contained in the mixed gas are reacted with the catalyst, so that the mixed gas can be discharged to the atmosphere with the hydrogen concentration further reduced.

  The on-vehicle fuel cell system according to the present invention preferably further includes a valve that is disposed in the first flow path and that allows the hydrogen off gas to pass through and shut off from the mixing unit by opening and closing.

  By providing such a valve, the hydrogen off-gas can be discharged at a desired timing. The valve may be capable of adjusting the flow rate to the mixing portion of the hydrogen off gas.

In the first vehicle-mounted fuel cell system of the present invention,
A fourth flow path connected to the hydrogen gas supply port of the fuel cell and flowing the supplied hydrogen gas;
Connecting the first location between the outlet of the fuel cell and the valve in the first flow path and the second location in the fourth flow path, from the fuel cell; It is preferable to further comprise a fifth flow path for flowing the discharged hydrogen off-gas and returning it to the fourth flow path.

  With this configuration, the hydrogen off-gas discharged from the fuel cell is returned to the fuel cell supply port, and the hydrogen gas circulates. Therefore, the apparent flow rate of the hydrogen gas supplied to the fuel cell is large. Since the flow rate is also increased, the output voltage of the fuel cell can be increased. Further, since impurities contained in the hydrogen gas are also made uniform throughout the hydrogen gas flow path, there is no possibility that the impurities interfere with the power generation operation of the fuel cell.

In the first vehicle-mounted fuel cell system of the present invention,
A sixth flow path connected to the oxidizing gas supply port of the fuel cell and flowing the supplied oxidizing gas;
A flow rate variable unit arranged in the second flow path or the sixth flow path and capable of changing a flow rate of the discharged oxygen off-gas;
A control unit for controlling the valve and the flow rate variable unit;
Further comprising
When the control unit opens the valve, it is preferable that the flow rate of the oxygen off-gas discharged by the flow rate variable unit is increased from a predetermined flow rate.

  In the hydrogen off-gas exhaust method of the present invention, the step (a) increases the flow rate of the oxygen off-gas discharged from the fuel cell from a predetermined flow rate when the hydrogen off-gas is mixed with the oxygen off-gas. It is preferable to include a process.

  As described above, when the hydrogen off gas is mixed with the oxygen off gas, the flow rate of the oxygen off gas is increased. Therefore, even if a large amount of hydrogen off gas is discharged, the hydrogen off gas is sufficiently absorbed by the large amount of nitrogen rich gas. Diluted. Therefore, the mixed gas can be discharged into the atmosphere in a state where the hydrogen concentration contained in the mixed gas is further reduced.

In the first vehicle-mounted fuel cell system of the present invention,
A sixth flow path connected to the oxidizing gas supply port of the fuel cell and flowing the supplied oxidizing gas;
A flow rate variable unit arranged in the second flow path or the sixth flow path and capable of changing a flow rate of the discharged oxygen off-gas;
A control unit for controlling the valve and the flow rate variable unit;
Further comprising
The control unit preferably opens the valve when the flow rate of the oxygen off-gas discharged by the flow rate variable unit exceeds a predetermined flow rate.

  In the hydrogen off-gas discharge method of the present invention, the step (a) includes mixing the hydrogen off-gas with the oxygen off-gas when the flow rate of the oxygen off-gas discharged from the fuel cell exceeds a predetermined flow rate. It is preferable that the process to include is included.

  Thus, since the hydrogen offgas is mixed with the oxygen offgas when the flow rate of the oxygen offgas increases, even if a large amount of hydrogen offgas is discharged, the hydrogen offgas is sufficiently absorbed by a large amount of nitrogen-rich gas. Diluted. Therefore, the mixed gas can be discharged into the atmosphere with the hydrogen concentration contained in the mixed gas lowered.

In the first vehicle-mounted fuel cell system of the present invention,
A control unit for controlling the valve;
The control unit preferably causes the valve to repeatedly open and close at a relatively short period when sending the discharged oxygen off gas to the mixing unit.

  In the hydrogen off-gas exhaust method of the present invention, the step (a) preferably includes a step of mixing the hydrogen off-gas with the oxygen off-gas at discrete timings having a relatively short period.

  By adopting such a configuration, the hydrogen off-gas is mixed with the nitrogen-rich oxygen off-gas in small portions in several portions, so that even if the oxygen off-gas flow rate does not increase, the hydrogen off-gas is sufficiently diluted. Can be Therefore, since the concentration of hydrogen contained in the mixed gas decreases, the mixed gas can be discharged into the atmosphere with a sufficiently low hydrogen concentration.

  In the first in-vehicle fuel cell system according to the present invention, the flow rate of the hydrogen off gas, which is disposed between the valve and the mixing unit in the first flow path, is introduced from the valve, It is preferable to further include a flow rate reduction unit that sends the mixture to the mixing unit.

In the hydrogen off-gas discharge method of the present invention, the step (a)
Reducing the flow rate of the hydrogen off-gas discharged from the fuel cell;
Mixing the hydrogen off-gas having a reduced flow rate with the oxygen off-gas;
It is preferable to contain.

  Thus, since the flow rate of the hydrogen off gas is reduced in mixing with the oxygen off gas, the hydrogen off gas can be sufficiently diluted even if the flow rate of the oxygen off gas does not increase. Therefore, the concentration of hydrogen contained in the mixed gas can be sufficiently reduced, and the mixed gas can be discharged into the atmosphere with a sufficiently low hydrogen concentration.

The second vehicle-mounted fuel cell system of the present invention for solving at least a part of the above-described problems is
In-vehicle fuel installed in a vehicle that is supplied with hydrogen gas and oxidant gas, and that uses these hydrogen gas and oxidant gas to generate electric power and has a fuel cell that discharges used hydrogen off-gas and oxygen off-gas. A battery system,
A diffusion member for diffusing the gas flow flowing out from the end opening of the flow path in the opening radial direction is provided at the end of the flow path for discharging the hydrogen off gas or the gas containing the off gas into the atmosphere.

  In the first on-vehicle fuel cell system of the present invention described above, a diffusion member for diffusing the gas flow flowing out from the end opening of the flow path in the opening diameter direction is provided at the end of the third flow path. It is preferable to do.

  In this way, the gas is discharged into the atmosphere while being discharged from the end opening of the gas flow path and simultaneously being diffused in the opening diameter direction. In this way, the exhaust gas (hydrogen off-gas) diffused and discharged in all directions increases the chance of contact with the air around the end of the flow path, and dilution proceeds accordingly. Therefore, the hydrogen concentration can be rapidly reduced at the end of the flow path without causing a situation in which gas discharge is continued while the hydrogen concentration remains high. Such a diffusing member may be opposite to the channel end, or may be provided in the channel end opening after the channel end is expanded in a trumpet shape.

  In the first and second in-vehicle fuel cell systems of the present invention described above, a shielding member is provided at the end of the flow path so as to cover the end with a predetermined distance, and the shielding member has a predetermined diameter. It may have one or a plurality of holes.

In this way, the shielding member allows gas permeation from the end of the flow path and prevents direct ignition source from approaching the end opening of the flow path. Therefore, as described above, coupled with gas discharge under a low hydrogen concentration situation, it is preferable because reliability of avoidance of ignition of mixed gas (exhaust gas) can be improved. In this case, the shielding member may be, for example, a mesh or a porous punch, and the distance from the end of the flow path does not hinder the flow of gas from the end opening, and the end opening The distance may be such that the direct approach of the ignition source to can be substantially avoided. Also, as the hole diameter and the number of holes in the shielding member,
Any material that can substantially avoid direct access of the ignition source to the end opening may be used.

1 is a configuration diagram showing an in-vehicle fuel cell system as a first embodiment of the present invention. FIG. 3 is a flowchart for explaining an example of a method for discharging hydrogen off-gas in the in-vehicle fuel cell system of FIG. 1. 6 is a flowchart for explaining another example of a method for discharging hydrogen off-gas in the in-vehicle fuel cell system of FIG. 1. 6 is a flowchart for explaining another example of a method for discharging hydrogen off-gas in the in-vehicle fuel cell system of FIG. 1. It is explanatory drawing for demonstrating the buffer arrange | positioned between the shut valve 414 and the mixing part 411 of FIG. It is a block diagram which shows the vehicle-mounted fuel cell system as 2nd Example of this invention. It is a block diagram which shows the vehicle-mounted fuel cell system as the 3rd Example of this invention. It is a schematic perspective view which shows the principal part of the discharge system of hydrogen off gas. It is explanatory drawing explaining the periphery of the offgas discharge port 524. FIG. It is explanatory drawing explaining the periphery of the offgas discharge port 524 taking the relationship with a vehicle body. It is explanatory drawing explaining the oxygen off-gas discharge flow path 503 and the diffusion plate 530 of a modification. It is explanatory drawing for demonstrating the buffer 413 of a modification.

Hereinafter, embodiments of the present invention will be described in the following order based on examples.
A. First embodiment:
A-1. Configuration of the first embodiment:
A-2. Operation of the first embodiment:
B. Second embodiment:
B-1. Configuration of the second embodiment:
B-2. Operation of the second embodiment:
C. Third embodiment:
C-1. Configuration of the third embodiment:
C-2. Operation of the third embodiment:
D. Variations:

A. First embodiment:
A-1. Configuration of the first embodiment:
FIG. 1 is a block diagram showing an in-vehicle fuel cell system as a first embodiment of the present invention. The fuel cell system according to the present embodiment is mounted on a vehicle such as an automobile, and mainly includes a fuel cell 100 that generates power by receiving supply of hydrogen gas, and supplies hydrogen gas to the fuel cell 100. And a hydrogen storage alloy tank 200.

  Among these, the fuel cell 100 receives supply of an oxidizing gas (for example, air) containing oxygen in addition to hydrogen gas containing hydrogen, and at the hydrogen electrode and the oxygen electrode, according to the reaction formula shown below, It causes an electrochemical reaction and generates electric power.

  That is, when hydrogen gas is supplied to the hydrogen electrode and oxidizing gas is supplied to the oxygen electrode, the reaction of formula (1) occurs on the hydrogen electrode side, and the reaction of formula (2) occurs on the oxygen electrode side. As for, reaction of Formula (3) is performed.

_{^{H 2 → 2H + + 2e -}} ... (1)
2H ⁺ + 2e ⁻ + (1/2) O ₂ → H ₂ O (2)
H ₂ + (1/2) O ₂ → H ₂ O (3)
When such a fuel cell 100 is used as a power source for a vehicle, an electric motor (not shown) is driven by the electric power generated from the fuel cell 100, and the generated torque is transmitted to an axle (not shown). Get the driving force.

  The fuel cell 100 has a stack structure in which a plurality of single cells are stacked, and each single cell includes an electrolyte membrane (not shown) and a diffusion electrode (not shown) that sandwiches it from both sides. A certain hydrogen electrode and oxygen electrode and two separators (not shown) sandwiching them from both sides are formed. Concavities and convexities are formed on both surfaces of the separator, and a gas flow path in a single cell is formed between the sandwiched hydrogen electrode and oxygen electrode. Among these, the hydrogen gas supplied as described above is formed in the gas flow path in the single cell formed between the hydrogen electrode and the gas flow path in the single cell formed in the single cell formed between the oxygen electrode is oxidized. Each gas is flowing.

  On the other hand, the hydrogen storage alloy tank 200 includes a hydrogen storage alloy (not shown) therein. In general, a hydrogen storage alloy has an endothermic reaction when it is heated to release hydrogen, and when it is cooled, it has a property of generating a heat dissipation reaction and storing hydrogen. Therefore, when extracting hydrogen from the hydrogen storage alloy, the hydrogen storage alloy in the hydrogen storage alloy tank 200 is heated by a heat exchange system (not shown).

  Since the hydrogen storage alloy deteriorates when impurities are present, high-purity hydrogen is stored in the hydrogen storage alloy tank 200.

  In addition, as shown in FIG. 1, the fuel cell system of the present embodiment includes a hydrogen gas channel for circulating hydrogen gas in the system, an oxidizing gas channel for circulating oxidizing gas, and a control unit 50. It has.

  Among these, the hydrogen gas flow path includes a main flow path 401 from the discharge port of the hydrogen storage alloy tank 200 to the supply port of the fuel cell 100 and a main flow path 401 from the discharge port of the fuel cell 100 via a pump 410 described later. , A bypass channel 405 branched from the main channel 401 to the circulation channel 403, a discharge channel 407 for discharging impurities in the circulating hydrogen gas, and a pressure abnormality A relief channel 409 for discharging hydrogen gas at times.

  In the main flow path 401, a shut valve 202 is disposed at the discharge port of the hydrogen storage alloy tank 200, and a pressure sensor 400, a shut valve 402, and a pressure reducing valve 404 are disposed in the middle of the flow path. A shut valve 102 is disposed at the supply port. In the circulation channel 403, a shut valve 104 is disposed at the discharge port of the fuel cell 100, and a gas-liquid separator 406, a shut valve 408, and a pump 410 are disposed in the middle of the channel. Further, a shut valve 412 is disposed in the bypass flow path 405, a shut valve 414 is disposed in the discharge flow path 407, and a relief valve 416 is disposed in the relief flow path 409.

  On the other hand, the oxidizing gas channel includes an oxidizing gas supply channel 501 for supplying oxidizing gas to the fuel cell 100, and an oxygen off-gas discharging channel 503 for discharging oxygen off-gas discharged from the fuel cell 100. I have.

  An air cleaner 502, a compressor 504, and a humidifier 506 are disposed in the oxidizing gas supply channel 501. Further, a gas-liquid separator 508 and a combustor 510 are arranged in the oxygen off-gas discharge flow path 503.

  Note that the above-described discharge passage 407 of the hydrogen gas passage is connected to the oxygen off-gas discharge passage 503 of the oxidation gas passage, and the vicinity of the connection portion constitutes the mixing portion 411.

  In addition, the control unit 50 inputs the detection result from the pressure sensor 400, and controls each valve 102, 104, 202, 402, 408, 412, 414, the pump 410, and the compressor 504, respectively. Note that control lines and the like are omitted for easy viewing of the drawing.

A-2. Operation of the first embodiment:
First, the flow of the oxidizing gas will be briefly described. By driving the compressor 504 by the control unit 50, air in the atmosphere is taken in as oxidant gas and purified by the air cleaner 502, then passes through the oxidant gas supply channel 501, and passes through the humidifier 506 to the fuel cell 100. Supplied. The supplied oxidizing gas is used as the above-described electrochemical reaction in the fuel cell 100 and then discharged as an oxygen off gas. The discharged oxygen off gas passes through the oxygen off gas discharge channel 503 and is discharged into the atmosphere outside the vehicle via the gas-liquid separator 508 and the combustor 510.

  Next, the flow of hydrogen gas will be described. The control unit 50 causes the shut valve 202 of the hydrogen storage alloy tank 200 and the shut valves 102 and 104 of the fuel cell 100 to be basically opened during operation of the fuel cell system, but closed when stopped.

  In addition, during normal operation, the control unit 50 opens the shut valve 402 of the main flow path 401 and the shut valve 408 of the circulation flow path 403 in addition to these, but the shut valve 412 of the bypass flow path 405, The shut valve 414 of the discharge channel 407 is closed. The relief valve 416 is closed except when the pressure is abnormal. The pressure sensor 400 detects the pressure of the hydrogen gas released from the hydrogen storage alloy tank 200.

  During normal operation, as described above, the hydrogen gas storage alloy in the hydrogen storage alloy tank 200 is heated by the heat exchange system to release the hydrogen gas, and the released hydrogen gas is reduced in pressure through the main flow path 401. After being depressurized by the valve 404, it is supplied to the fuel cell 100. The supplied hydrogen gas is used as the above-described electrochemical reaction in the fuel cell 100 and then discharged as a hydrogen off gas. The discharged hydrogen off-gas passes through the circulation channel 403, and after the liquid component of water contained in the hydrogen off-gas is removed by the gas-liquid separator 406, it is returned to the main channel 401 through the pump 410. The fuel cell 100 is supplied again. At this time, when the pump 410 provided in the circulation flow path 403 is driven, the hydrogen off-gas passing through the circulation flow path 403 is vigorously sent out to the main flow path 401. Thus, during normal operation, hydrogen gas circulates through the main flow channel 401 and the circulation channel 403.

  In this manner, by returning the hydrogen off-gas to the main flow path 401 and circulating the hydrogen gas, even if the amount of hydrogen used in the fuel cell 100 is the same, the apparent amount of hydrogen gas supplied to the fuel cell 100 is apparent. Since the flow rate is increased and the flow velocity is increased, advantageous conditions are created from the viewpoint of supplying hydrogen to the fuel cell 100. As a result, the output voltage of the fuel cell 100 also increases.

  Further, although impurities such as nitrogen contained in the oxidizing gas permeate the electrolyte membrane from the oxygen electrode side and leak to the hydrogen electrode side, by circulating the hydrogen off-gas as described above, these impurities are transferred to the hydrogen electrode. It does not cause a situation such as accumulation. Therefore, the retention of impurities such as nitrogen does not cause the fuel cell 100 to interfere with the power generation operation and the output voltage does not drop.

  The driving of the pump 410 is controlled by the control unit 50, and the flow rate of the hydrogen off-gas flowing through the circulation flow path 403 is changed according to the power consumption generated by the fuel cell 100.

  The above is a schematic description of the flow of hydrogen gas during normal operation. Next, the flow of hydrogen gas at the time of cold start will be described.

  In general, the higher the temperature, the higher the pressure of hydrogen released from the hydrogen storage alloy, and the lower the temperature, the lower the pressure of released hydrogen. Therefore, the lower the temperature of the hydrogen storage alloy tank, the more hydrogen is released. It becomes difficult to be done. Therefore, when starting at a low temperature, hydrogen gas is drawn from the hydrogen storage alloy tank 200 by the pump 410.

  When the fuel cell system is started, when the ambient temperature is low and the pressure of the hydrogen gas detected by the pressure sensor 400 is lower than the reference pressure, the control unit 50 circulates the shut valve 402 of the main flow channel 401 and the circulation valve. The shut valve 408 of the flow path 403 and the shut valve 414 of the discharge flow path 407 are closed, the shut valve 412 of the bypass flow path 405 is opened, and the pump 410 is driven at a high rotational speed. Thereby, even if the temperature of the hydrogen storage alloy tank 200 is low and the pressure of the released hydrogen gas is low, the stored hydrogen gas is sufficiently extracted from the hydrogen storage alloy tank 200. The drawn hydrogen gas enters the bypass channel 405 from the main channel 401 and then returns to the main channel 401 through the circulation channel 403 and is supplied to the fuel cell 100. The supplied hydrogen gas is subjected to an electrochemical reaction in the fuel cell 100 and then becomes hydrogen off-gas and is discharged to the circulation flow path 403. Note that the concentration of impurities contained in the hydrogen off-gas increases as time passes. Therefore, in order to remove the impurities, the shut-off valve 414 is sometimes opened to release the hydrogen off-gas from the discharge passage 407.

  The above is the description of the flow of hydrogen gas at the time of cold start. Next, the discharge of hydrogen off gas, which is a feature of the present invention, will be described in detail.

  During normal operation of the fuel cell system, as described above, the hydrogen off-gas discharged from the fuel cell 100 is supplied to the main flow channel 401 via the circulation channel 403 in order to uniformize impurities contained in the hydrogen gas. By returning to, hydrogen gas is circulated. However, even if the hydrogen gas is made uniform in this way, the impurities always leak from the oxygen electrode side to the hydrogen electrode side in the fuel cell 100. Therefore, after a long period of time, the hydrogen gas becomes uniform. The concentration of impurities therein gradually increases, and the concentration of hydrogen decreases accordingly.

  Therefore, a shut valve 414 is provided in the discharge channel 407 branched from the circulation channel 403. When the concentration of impurities in the circulating hydrogen gas increases, the controller 50 opens the shut valve 414. A part of hydrogen gas containing circulating impurities is discharged. Thereby, a part of the hydrogen gas containing impurities is discharged from the circulation path, and pure hydrogen gas from the hydrogen storage alloy tank 200 is introduced by that amount, so that the concentration of impurities in the hydrogen gas decreases, Conversely, the hydrogen concentration increases. As a result, the fuel cell 100 can appropriately perform power generation continuously. The time interval at which the shut valve 414 is opened varies depending on operating conditions and output, but may be about once every 5 seconds, for example.

Further, as described above, on the oxygen electrode side in the fuel cell 100, water (H ₂ O) is generated according to the formula (2), and the water is vaporized from the oxygen electrode side to the hydrogen electrode side through the electrolyte membrane. Leaks out. In this embodiment, when the shut valve 414 is opened and the hydrogen gas is discharged, a rapid flow can be generated in the hydrogen gas due to the pressure difference, and the moisture in the battery cell can be blown away with the force. For this reason, even if the water (water vapor) generated as the formula (2) progresses condenses and sticks to the hydrogen electrode side in the single cell, the water is blown off by the rapid hydrogen gas flow. There is no such thing as stopping the flow of hydrogen gas.

  In this embodiment, the concentration of impurities in the circulating hydrogen gas is not particularly detected, and the time until the concentration of impurities becomes unacceptable from the accumulation of past data is derived in advance. ing. Then, the control unit 50 measures the passage of time with a timer, and periodically opens the shut valve 414 every time the above-described time passes. However, a hydrogen concentration sensor or the like may be provided in the hydrogen gas flow path to detect the hydrogen concentration in the circulating hydrogen gas, and when the concentration falls below the reference concentration, the shut valve 414 may be opened.

  Next, the hydrogen gas discharged from the shut valve 414 passes through the discharge flow path 407 and is sent to the oxygen off gas discharge flow path 503, and is mixed with the oxygen off gas flowing through the oxygen off gas discharge flow path 503 in the mixing unit 411. The Since the hydrogen gas discharged from the shut valve 414 is a hydrogen off gas, the hydrogen concentration is low to some extent. The oxygen off gas discharged from the fuel cell 100 is also a nitrogen-rich gas in which oxygen is consumed in the fuel cell 100. Therefore, by mixing and diluting the hydrogen off gas with the oxygen off gas in this way, the concentration of hydrogen contained in the mixed gas is further reduced.

  Next, the gas mixed in the mixing unit 411 flows into the combustor 510 via the gas-liquid separator 508. The combustor 510 includes a platinum catalyst 512, and reacts hydrogen contained in the mixed gas with oxygen by combustion to further reduce the concentration of hydrogen contained in the mixed gas.

  In this way, the mixed gas whose hydrogen concentration has been reduced by the combustor 510 is then discharged into the atmosphere.

  As described above, the oxygen off-gas discharged from the fuel cell 100 contains a large amount of moisture, and when the oxygen off-gas discharge channel 503 is long, it is likely to condense and form water droplets. Therefore, even if such oxygen off-gas is mixed with hydrogen off-gas in the mixing unit 411, moisture is still contained. Therefore, when the mixed gas passes through the combustor 510, the contained moisture is condensed. It may become water droplets and adhere to the platinum catalyst 512. In the present embodiment, as described above, the gas-liquid separator 508 is provided in the previous stage of the combustor 510 to remove the liquid component of the water contained in the mixed gas, so that water droplets are formed on the platinum catalyst 512 in the combustor 510. And the activity of the platinum catalyst 512 can be maintained.

  Further, even if the shut valve 414 is opened during the power generation operation of the fuel cell 100, there is no problem because the output voltage of the fuel cell 100 only drops for a moment and does not cause a large voltage drop.

  As described above, in the present embodiment, the hydrogen off-gas discharged from the fuel cell 100 is diluted by mixing with the oxygen off-gas in the mixing unit 411, and the concentration of hydrogen contained in the mixed gas is further increased by the combustor 510. To reduce. Therefore, after reducing the hydrogen concentration to a sufficiently low concentration that is effective for avoiding ignition and then exhausting it to the atmosphere, the reliability of avoiding ignition can be improved.

  By the way, when the control unit 50 opens the shut valve 414 and discharges the hydrogen off-gas to the mixing unit 411, the mixing of the oxygen off-gas and the mixing in the mixing unit 411 is performed even when a large amount of hydrogen off-gas is discharged. The following measures were taken in order to maintain the dilution and improve the reliability of ignition avoidance.

  In the present embodiment, as one of the countermeasures described above, any one of the four methods described below is used to improve the reliability of ignition avoidance.

  First, the first method will be described with reference to FIG. FIG. 2 is a flowchart for explaining an example of a method for discharging hydrogen off-gas in the in-vehicle fuel cell system of FIG.

  When the elapsed time or sensor detects that the concentration of impurities in the circulating hydrogen gas has become unacceptable, the controller 50 starts the process shown in FIG. Control is performed so that the compressor 504 disposed in the path 501 is driven at a specific output or higher (for example, maximum output) (step S102). As a result, the flow rate of the oxidizing gas taken in via the air cleaner 502 is increased, and accordingly, the flow rate of the oxygen offgas discharged from the fuel cell 100 and flowing through the oxygen offgas discharge flow path 503 is also increased. Next, the control unit 50 opens the shut valve 414 (step S104), and discharges the circulating hydrogen gas (hydrogen offgas) from the shut valve 414 to the mixing unit 411. When the predetermined opening time has elapsed (step S106), the shut valve 414 is closed (step S108), and the processing shown in FIG. The opening time of the shut valve 414 is preferably 1 sec or less, and more preferably about 500 msec.

  When such a method is used, when the shutoff valve 414 is opened and the hydrogen offgas is discharged to the mixing unit 411, the flow rate of the oxygen offgas flowing through the oxygen offgas discharge channel 503 is increased. When the hydrogen off gas is mixed with the oxygen off gas, the hydrogen off gas is sufficiently diluted with a large amount of nitrogen-rich gas. Therefore, since the concentration of hydrogen contained in the mixed gas decreases, the reliability of avoiding ignition can be improved.

  Next, the second method will be described with reference to FIG. FIG. 3 is a flowchart for explaining another example of the method for discharging hydrogen off-gas in the in-vehicle fuel cell system of FIG.

  In the method shown in FIG. 2, when the shut valve 414 is opened, the compressor 504 is positively driven, for example, at the maximum output, and the hydrogen off gas is discharged after the flow rate of oxygen off gas increases. . However, for example, if the compressor 504 is driven at the maximum output regardless of the traveling state while the vehicle is traveling, the driver may feel uncomfortable. Specifically, if the compressor 504 is driven at the maximum output in an attempt to discharge the hydrogen off-gas during the slow operation, the compressor 504 causes a large amount of rotational noise and vibration despite the slow operation. This will cause the driver to feel uncomfortable.

  Therefore, in the second method, the shut valve 414 is opened in accordance with the driving of the compressor 504 that changes in accordance with the running state (in other words, load fluctuation).

  Specifically, when the processing shown in FIG. 3 is started, the control unit 50 first waits until the output of the compressor 504 exceeds the specific output (step S202). The output of the compressor 504 can be derived from the output result of a rotation speed sensor or the like attached to the compressor 504.

  Thereafter, when the output of the compressor 504 changes according to the traveling state and exceeds the specific output, the control unit 50 opens the shut valve 414 (step S204). Thereby, the hydrogen off-gas can be discharged from the shut valve 414 to the mixing unit 411 at the timing when the flow rate of the oxygen off-gas flowing through the oxygen off-gas discharge channel 503 is increased. When the predetermined opening time has elapsed (step S206), the shut valve 414 is closed (step S208), and the processing shown in FIG.

  When such a method is used, as described above, when the flow rate of the oxygen off gas is increased, the hydrogen off gas is discharged to the mixing unit 411. Therefore, in the mixing unit 411, as in the method illustrated in FIG. When the off gas is mixed with the oxygen off gas, the hydrogen off gas is sufficiently diluted with a large amount of nitrogen rich gas. Therefore, since the concentration of hydrogen contained in the mixed gas decreases, the reliability of avoiding ignition can be improved.

  In addition, since the driving of the compressor 504 changes according to the traveling state, the rotation sound and vibration match the traveling state, and there is no possibility of giving the driver a sense of incongruity.

  Next, the third method will be described with reference to FIG. FIG. 4 is a flowchart for explaining another example of a method for discharging hydrogen off-gas in the in-vehicle fuel cell system of FIG.

  When the processing shown in FIG. 4 is started, the control unit 50 first opens the shut valve 414 (step S302) and immediately closes (step S304). Then, the control unit 50 determines whether or not a predetermined time has elapsed from the start of the process (step S306), and if not, repeats the above-described operation. As a result, the shut valve 414 is repeatedly opened and closed at a relatively short cycle. Thereafter, when a predetermined time has elapsed, the processing shown in FIG.

  When such a method is used, as described above, the shut valve 414 repeats opening and closing with a relatively short cycle, so that the hydrogen off-gas is divided into several portions at a discrete timing with a relatively short cycle. Then, it is discharged to the mixing unit 411. Therefore, when mixing with the oxygen off gas in the mixing unit 411, the hydrogen off gas can be sufficiently diluted even if the flow rate of the oxygen off gas does not increase. Therefore, since the concentration of hydrogen contained in the mixed gas decreases, the reliability of avoiding ignition can be improved.

  Next, the fourth method will be described with reference to FIG. In this method, a buffer 413 as shown in FIG. 5 is provided in advance between the shut valve 414 and the mixing unit 411 in the circulation channel 403 of FIG. FIG. 5 is an explanatory diagram for explaining a buffer disposed between the shut valve 414 and the mixing unit 411 in FIG. 1.

  As shown in FIG. 5, in the buffer 413, the outlet diameter is narrower than the inlet diameter, and the space between the inlet and the outlet has a large volume. Is vacant. Therefore, even if a large amount of hydrogen off-gas is discharged from the shut valve 414 in a short time even if a large amount of hydrogen off-gas is discharged from the shut valve 414 in a short time by the control unit 50, the shut valve 414 is opened and then closed. Therefore, it receives resistance and stays in the central space, and flows out from the outlet to the mixing unit 411 only in small amounts. Therefore, when mixing with the oxygen off gas in the mixing unit 411, the hydrogen off gas can be sufficiently diluted even if the flow rate of the oxygen off gas does not increase. Therefore, the concentration of hydrogen contained in the mixed gas can be sufficiently reduced, and the reliability of avoiding ignition can be increased.

B. Second embodiment:
B-1. Configuration of the second embodiment:
FIG. 6 is a block diagram showing an in-vehicle fuel cell system as a second embodiment of the present invention. In the fuel cell system of the first embodiment, the hydrogen storage alloy tank 200 is used as a hydrogen gas supply source. However, in the fuel cell system of this embodiment, high-pressure hydrogen is used instead of the hydrogen storage alloy tank 200. A gas tank 300 is used.

  The high-pressure hydrogen gas tank 300 is filled with high-pressure hydrogen gas, and when a shut valve 302 attached to the root is opened, hydrogen gas having a pressure of about 20 to 35 MPa is released.

  Further, since the fuel cell 100 has the same configuration as that of the first embodiment, description thereof is omitted.

  In addition, as shown in FIG. 6, the fuel cell system of the present embodiment includes a hydrogen gas flow path, an oxidizing gas flow path, and a control unit 50. However, the oxidizing gas flow path is the first embodiment. Since it is the same structure as an example, description is abbreviate | omitted.

  The hydrogen gas flow path includes a main flow path 401 extending from the discharge port of the high-pressure hydrogen gas tank 300 to the supply port of the fuel cell 100, and a circulation flow path 403 returning from the discharge port of the fuel cell 100 to the main flow path 401 via the pump 410. And a discharge flow path 407 for discharging impurities in the circulating hydrogen gas, and a relief flow path 409 for discharging hydrogen gas when the pressure is abnormal. In this embodiment, since the high-pressure hydrogen gas tank 300 is used as a hydrogen gas supply source, high-pressure hydrogen gas can be released. Therefore, unlike the case of the hydrogen storage alloy tank 200, the bypass channel 405 is not provided because it is not necessary to draw out hydrogen gas at the time of low temperature start.

  In the main flow path 401, a shut valve 302 is disposed at the discharge port of the high-pressure hydrogen gas tank 300, and a decompression valve 418, a heat exchanger 420, a decompression valve 422, and a gas-liquid separator 425 are disposed in the middle of the flow path. A shut valve 102 is disposed at the supply port of the fuel cell 100. In the circulation channel 403, the shut valve 104 is disposed at the discharge port of the fuel cell 100, and the gas-liquid separator 406, the pump 410, and the check valve 426 are disposed in the middle of the channel. Note that a shut valve 414 is disposed in the discharge flow path 407 and a relief valve 416 is disposed in the relief flow path 409, and the discharge flow path 407 is connected to the oxygen off-gas discharge flow path 503. The point which comprises the mixing part 411 is the same as that of the case of a 1st Example.

  The control unit 50 inputs the detection result from the pressure sensor 400 and controls each of the valves 102, 104, 302, and 414, the pump 410, and the compressor 504. Note that control lines and the like are omitted for easy viewing of the drawing.

B-2. Operation of the second embodiment:
Now, the flow of hydrogen gas will be briefly described. Since the flow of the oxidizing gas is the same as that in the first embodiment, description thereof is omitted.

  The control unit 50 causes the shut valve 302 of the high-pressure hydrogen gas tank 300 and the shut valves 102 and 104 of the fuel cell 100 to be basically opened during operation of the fuel cell system, but closed when stopped.

  In addition, during normal operation, the shut valve 414 of the discharge channel 407 is closed by the control unit 50. The relief valve 416 is closed except in the case of abnormal pressure, as in the case of the first embodiment.

  During normal operation, as described above, when the control unit 50 opens the shut valve 302, hydrogen gas is released from the high-pressure hydrogen gas tank 300, and the released hydrogen gas passes through the main flow path 401 and the pressure reducing valve 418. After being depressurized, the heat exchanger 420 warms it. The heated hydrogen gas is further depressurized by the pressure reducing valve 422, and then the liquid component of water contained in the hydrogen gas is removed by the gas-liquid separator 425 and supplied to the fuel cell 100. The supplied hydrogen gas is used as the above-described electrochemical reaction in the fuel cell 100 and then discharged as a hydrogen off gas. The discharged hydrogen off-gas passes through the circulation channel 403, and after the liquid component of water contained in the hydrogen off-gas is removed by the gas-liquid separator 406, it is returned to the main channel 401 through the pump 410. The fuel cell 100 is supplied again. At this time, as in the case of the first embodiment, the pump 410 provided in the middle of the circulation flow path 403 is driven, so that the hydrogen off-gas passing through the circulation flow path 403 gains momentum and the main flow flow path 401. Sent out. Thus, during normal operation, hydrogen gas circulates through the main flow channel 401 and the circulation channel 403. A check valve 426 is provided between the connection point with the main flow path 401 and the pump 410 in the circulation flow path 403 so that the circulating hydrogen off-gas does not flow backward. ing.

  The above is the description of the flow of hydrogen gas in this embodiment. Next, the discharge of hydrogen off gas, which is a feature of the present invention, will be described in detail.

  Also in the present embodiment, as in the first embodiment, a shut valve 414 is provided in the discharge flow path 407 branched from the circulation flow path 403, and the shut valve 414 allows hydrogen gas containing impurities (hydrogen Off gas). Then, the hydrogen off-gas discharged from the shut valve 414 is mixed with the oxygen off-gas flowing through the oxygen off-gas discharge channel 503 and diluted in the mixing unit 411, thereby reducing the concentration of hydrogen contained in the mixed gas. . Further, the mixed gas flows into the combustor 510 through the gas-liquid separator 508, and in the combustor 510, hydrogen contained in the mixed gas is reacted with oxygen using the platinum catalyst 512, and is contained in the mixed gas. Further reduce the concentration of hydrogen. Thus, the mixed gas whose hydrogen concentration is reduced by the combustor 510 is then discharged into the atmosphere.

  Therefore, also in this embodiment, as in the first embodiment, the hydrogen off-gas discharged from the fuel cell 100 is diluted by mixing with the oxygen off-gas in the mixing unit 411, and the concentration of hydrogen contained in the mixed gas is reduced. Is reduced by the combustor 510. Therefore, after reducing the hydrogen concentration to a sufficiently low concentration that is effective for avoiding ignition and then exhausting it into the atmosphere, the reliability of avoiding ignition can be improved.

  Also in this embodiment, in order to ensure higher reliability, any one of the four methods described in the first embodiment is used to open the shut valve 414 and discharge the hydrogen off gas. Like to do.

  In the first embodiment, as shown in FIG. 1, the discharge passage 407 is connected to the fuel cell 100 because the hydrogen gas from the hydrogen storage alloy tank 200 flows through the circulation passage 403 at the time of low temperature start. However, in this embodiment, since only the hydrogen off-gas flows, the circulation flow path 403 is branched from the downstream side of the pump 410. Accordingly, since the hydrogen off-gas is pressurized by the pump 410 on the downstream side of the pump 410, in this embodiment, when the shut valve 414 is opened, the hydrogen off-gas can be discharged with a momentum.

C. Third embodiment:
C-1. Configuration of the third embodiment:
FIG. 7 is a block diagram showing an in-vehicle fuel cell system as a third embodiment of the present invention. The fuel cell system of the third embodiment includes a fuel cell 100 similar to that of the first embodiment, and uses a high-pressure hydrogen gas tank 300 similar to that of the second embodiment as the hydrogen gas supply source. Yes. In this embodiment, four high-pressure hydrogen gas tanks 300 are mounted in the vehicle. In this case, the hydrogen storage alloy tank 200 can be used as in the first embodiment. In the following description, for the devices that perform the same operations as those in the first and second embodiments, the same reference numerals are omitted and the description thereof is omitted.

  As shown in the drawing, in the fuel cell system of the third embodiment, the flow path configuration of the hydrogen gas / oxidizing gas flow path is partially different from that of the above embodiment.

  As in the above embodiment, the hydrogen gas flow path includes a main flow path 401 from the high-pressure hydrogen gas tank 300 to the fuel cell 100, a circulation flow path 403 of the fuel cell 100, a discharge flow path 407 for discharging impurities, a pressure And a relief channel 409 for discharging hydrogen gas at the time of abnormality. In addition, in the hydrogen gas flow channel of the present embodiment, another relief flow channel 430 for enhancing the reliability of hydrogen gas release when the pressure is abnormal, and a leak check flow channel 427 used for checking hydrogen gas leakage. And a supply flow path 432 extending from the hydrogen gas supply port 429 to the filling port of the high-pressure hydrogen gas tank 300.

  The main flow path 401 includes a discharge manual valve 304, a pressure reducing valve 418, a heat exchanger 420, and a pressure reducing valve 422 in addition to the shut valve 302 at the discharge port of the high-pressure hydrogen gas tank 300. Similar to the second embodiment, the circulation channel 403 includes a gas-liquid separator 406 and the like, and circulates hydrogen off-gas through the check valve 426 by the pump 410. The supply flow path 432 includes a check valve 306 and a filling manual valve 308 at the filling port of the high-pressure hydrogen gas tank 300. The discharge channel 407 has a shut valve 414 and a hydrogen diluter 424, the relief channels 430 and 409 have relief valves 415 and 416, and the leak check channel 427 has a leak check boat 428, respectively.

  The oxidant gas channel includes an oxidant gas supply channel 501 for supplying oxidant gas to the fuel cell 100 and an oxygen offgas discharge channel 503 for discharging oxygen offgas, as in the above embodiment. In addition, in the oxidizing gas flow path of the present embodiment, an oxygen off gas branch introduction flow path 505 for introducing oxygen off gas to a hydrogen diluter 424 described later, and a water circulation flow path for removing water in the introduction flow path 601.

  The equipment configuration in the oxidizing gas supply flow path 501 is the same as that in the second embodiment, and the humidifier 506 is configured to be capable of gas humidification also in the oxygen off-gas discharge flow path 503. The oxygen off-gas discharge channel 503 includes, from the fuel cell 100 side, a pressure regulating valve 509, the humidifier 506, a gas-liquid separator 520, and a muffler 522 that is a silencer. The exit is 524.

  The water circulation channel 601 includes pumps 602 and 606, a humidified water tank 604, and an injector 608. The water circulation channel 601 circulates and supplies the water separated by the gas-liquid separator 520 to the oxidizing gas supply channel 501 via the pumps 602 and 606.

  Furthermore, the control unit 50 inputs detection results obtained from various sensors (not shown), and controls the valves 102, 104, 302, and 414, the pumps 410, 602, and 606, and the compressor 504, respectively. The pump 410, the compressor 504, the pumps 602, 606, etc. are each driven by a motor, but these are not shown. The discharge manual valve 304 and the filling manual valve 308 are each manually opened and closed.

B-2. Operation of the second embodiment:
Next, the flow of gas will be described from the flow of oxidizing gas. When the controller 504 is driven by the control unit 50, air in the atmosphere is taken in as oxidizing gas, as in the first and second embodiments. The oxidizing gas is purified by the air cleaner 502 and pressurized by the compressor 504, and is supplied to the fuel cell 100 through the humidifier 506.

  The supplied oxidizing gas is used as the above-described electrochemical reaction in the fuel cell 100 and then discharged as an oxygen off gas. The discharged oxygen off gas passes through the oxygen off gas discharge flow path 503, passes through the pressure regulating valve 509, and then flows into the humidifier 506 again.

As described above, on the oxygen electrode side in the fuel cell 100, water (H ₂ O) is generated according to the formula (2). Therefore, the oxygen off-gas discharged from the fuel cell 100 is very wet, Contains moisture. On the other hand, the oxidizing gas (air) taken from the atmosphere and pressurized by the compressor 504 is a low humidity gas. In this embodiment, the oxidizing gas supply flow path 501 and the oxygen off gas discharge flow path 503 are passed through one humidifier 506, and water vapor is exchanged between them, so that the dry oxidizing gas is dried from the very wet oxygen off gas. Moisturize the water. As a result, the oxidizing gas flowing out from the humidifier 506 and supplied to the fuel cell 100 gets wet to some extent, and the oxygen off-gas flowing out from the humidifier 506 and discharged into the atmosphere outside the vehicle becomes dry to some extent. For this reason, there are the following advantages.

  First, the oxygen off gas is not discharged into the atmosphere outside the vehicle as it is through the oxygen off gas discharge flow path 503 while being very wet with the water generated as described above. Therefore, even when the ambient temperature is very low such as in winter, there is no possibility of any more smoke of water vapor coming from the off-gas outlet 524 of the vehicle. Second, the oxidizing gas (air) from the compressor 504 is not supplied to the fuel cell 100 in a dry state. Therefore, the surface on the oxygen electrode side of the electrolyte membrane in the fuel cell 100 is not dried, so that the reaction efficiency of the electrochemical reaction described above is not lowered.

  Thus, the oxygen off-gas that has been somewhat dried in the humidifier 506 is then flowed into the gas-liquid separator 520. In the gas-liquid separator 520, the oxygen off-gas from the humidifier 506 is gas-liquid separated into a gas component and a liquid component, and moisture contained in the oxygen off-gas is further removed as a liquid component to make it more dry. The removed water is recovered as recovered water, pumped up by a pump 602, and stored in a humidified water tank 604. The recovered water is sent out to the injector 608 by the pump 606, sprayed by the injector 608 at the inlet of the compressor 504, and mixed with the oxidizing gas from the air cleaner 502. By doing so, the oxidizing gas passing through the oxidizing gas supply channel 501 is further wetted.

  The oxygen off-gas further dried in the gas-liquid separator 520 as described above is then silenced by the muffler 522 and discharged from the off-gas discharge port 524 to the atmosphere outside the vehicle.

  Next, the flow of hydrogen gas will be described. The discharge manual valve 304 of the high-pressure hydrogen gas tank 300 is always open during normal times, and the filling manual valve 308 is always closed.

  Moreover, the open / closed states of the shut valve 302 of the high-pressure hydrogen gas tank 300 and the shut valves 102 and 104 of the fuel cell 100 are as described in the second embodiment.

  In addition, the shut valve 414 of the discharge channel 407 is basically closed by the control unit 50 during operation. The relief valves 415 and 416 are closed except when the pressure is abnormal.

  During operation, as described above, when the control unit 50 opens the shut valve 302, the hydrogen gas in the high-pressure hydrogen gas tank 300 is decompressed by the decompression valve 418 and by the heat exchanger 420, as in the second embodiment. It is supplied to the fuel cell 100 through heating, further decompression by the decompression valve 422, and the moisture liquid component in the gas-liquid separator 425. The supplied hydrogen gas is used as the above-described electrochemical reaction in the fuel cell 100 and then discharged as a hydrogen off gas. The discharged hydrogen off-gas is returned to the main flow path 401 from the circulation flow path 403 with the flow by the pump 410 as in the second embodiment, and is supplied to the fuel cell 100 again. Note that the backflow of the circulating hydrogen off-gas is avoided by the check valve 426 of the circulation channel 403.

  As described above in the first embodiment, the output voltage of the fuel cell 100 can be increased by returning the hydrogen off gas to the main flow channel 401 and circulating the hydrogen gas. .

  In addition, as described above in the first embodiment, the retention of impurities such as nitrogen contained in the oxidizing gas can be avoided by circulating the hydrogen off-gas and the decrease in the output voltage of the fuel cell 100 can be avoided. is there.

  The driving of the pump 410 is controlled by the control unit 50, and the flow rate of the hydrogen off-gas flowing through the circulation flow path 403 is changed according to the power consumption generated by the fuel cell 100.

  Two decompression valves, a decompression valve 418 for primary decompression and a decompression valve 422 for secondary decompression, are provided in the vicinity of the outlet of the high-pressure hydrogen gas tank 300. These decompression valves decompress the high-pressure hydrogen gas in the high-pressure hydrogen gas tank 300 in two stages. Specifically, the pressure is reduced from about 20 to 35 MPa to about 0.8 to 1 MPa by the pressure reducing valve 418 for primary pressure reduction, and further from about 0.8 to 1 MPa by the pressure reducing valve 422 for secondary pressure reduction. The pressure is reduced to about 0.2 to 0.3 MPa. As a result, the high-pressure hydrogen gas is not supplied to the fuel cell 200 and the fuel cell 200 is not damaged. The same applies to the second embodiment.

  The high-pressure hydrogen gas is reduced from about 20 to 35 MPa to about 0.8 to 1 MPa by the pressure reducing valve 418 for primary pressure reduction. Since the hydrogen release from the high-pressure hydrogen gas tank 300 involves expansion, the release temperature varies depending on the pressure and flow rate. In this embodiment, a heat exchanger 420 is arranged between the pressure reducing valve 418 for primary pressure reduction and the pressure reducing valve 422 for secondary pressure reduction, and a mechanism for exchanging heat with the hydrogen gas after pressure reduction is adopted. is doing. Although not shown, this heat exchanger 420 is supplied with cooling water circulating through the fuel cell 100, and heat exchange is performed between the cooling water and hydrogen gas whose temperature has changed. By passing through the heat exchanger 420, the temperature of the hydrogen gas becomes a substantially appropriate temperature range and can be supplied to the fuel cell 100. Accordingly, since a sufficient reaction temperature can be obtained in the fuel cell 100, the electrochemical reaction proceeds and an appropriate power generation operation can be performed. The same applies to the second embodiment.

Further, as described above, on the oxygen electrode side in the fuel cell 100, water (H ₂ O) is generated according to the equation (2), and the water enters the hydrogen electrode side through the electrolyte membrane from the oxygen electrode side as water vapor. Come. Therefore, the hydrogen off gas discharged from the fuel cell 100 is wet and contains a considerable amount of moisture. In this embodiment, a gas-liquid separator 406 is provided in the middle of the circulation channel 403, and the gas-liquid separator 406 performs gas-liquid separation of water contained in the hydrogen off gas, removes the liquid component, and gas (water vapor) ) Is sent to the pump 410 together with other gases. As a result, the water contained in the hydrogen off-gas recirculated to the main flow channel 401 is only a gas component, and no water is supplied to the fuel cell 100 as a gas-liquid mixture. For this reason, the hydrogen gas flow path is not blocked by the gas-liquid mixture, so that the power generation operation continues favorably in the fuel cell 100, and the output voltage of the single cell decreases and the power generation amount of the entire fuel cell 100 increases. Does not cause a drop in The same applies to the second embodiment.

  Further, as described above, the hydrogen gas is circulated in order to make the impurities contained in the hydrogen gas uniform. However, even if the hydrogen gas is made uniform in this way, the impurities always leak from the oxygen electrode side to the hydrogen electrode side in the fuel cell 100. Therefore, after a long period of time, the hydrogen gas becomes uniform. The concentration of impurities therein gradually increases, and the concentration of hydrogen decreases accordingly.

  Therefore, a shut valve 414 is provided in the discharge flow path 407 branched from the circulation flow path 403, and the shut valve 414 is periodically opened by the control unit 50, and a part of the hydrogen gas containing the circulating impurities is removed. It is discharging. By opening the shut valve 412, part of the hydrogen gas containing impurities is discharged from the circulation path, and pure hydrogen gas from the high-pressure hydrogen gas tank 300 is introduced accordingly. Thereby, the concentration of impurities in the hydrogen gas decreases, and conversely, the concentration of hydrogen increases. As a result, the fuel cell 100 can appropriately perform power generation continuously. The time interval for opening the shut valve 414 varies depending on the operating conditions and output, but may be about once every 5 seconds, for example.

  Even if the shut valve 414 is opened during the power generation operation of the fuel cell 100, there is no problem because the output voltage of the fuel cell 100 only drops for a moment and does not cause a large voltage drop. The opening time of the shut valve 414 is preferably 1 sec or less, and more preferably about 500 msec, for example.

  Next, the hydrogen off-gas discharge system and the state of gas discharge will be described. FIG. 8 is a schematic perspective view showing the main part of the hydrogen off-gas exhaust system. The hydrogen gas discharged from the shut valve 414 is supplied to the hydrogen diluter 424 through the discharge channel 407. The hydrogen diluter 424 is also supplied with oxygen off-gas through an oxygen off-gas branch introduction passage 505 branched from the oxygen off-gas discharge passage 503.

  The hydrogen diluter 424 is a housing in which a gas mixing chamber 424a is formed, and the volume of the mixing chamber is compared with the supply gas flow path (the discharge flow path 407 and the oxygen off-gas branch introduction flow path 505). Prepare to expand. The mixing chamber 424a is partitioned by a shielding plate 424b so that the gas flow path has a zigzag shape. The hydrogen diluter 424 having such a structure dilutes the hydrogen gas discharged from the shut valve 414 by mixing the hydrogen gas and the oxygen off gas supplied as described above in the mixing chamber 424a. The diluted hydrogen gas is fed into the oxygen off-gas discharge channel 503 and further mixed with the oxygen off-gas flowing through the oxygen off-gas discharge channel 503. The mixed gas passes through the downstream flow path 407a of the discharge flow path 407, joins the oxygen off-gas discharge flow path 503 downstream of the muffler 522, and is exhausted from the off-gas discharge port 524 to the atmosphere outside the vehicle.

Thus, according to the present embodiment for discharging the hydrogen off-gas, there are the following advantages.
First, hydrogen off-gas and oxygen off-gas were introduced into the mixing chamber 424a of the hydrogen diluter 424, and both gases were mixed and diluted in the mixing chamber 424a having a large volume. Accordingly, the hydrogen off-gas and the oxygen off-gas are efficiently mixed based on the expansion of the mixing chamber volume, so that it is possible to reliably dilute the hydrogen off-gas and thus reduce the hydrogen concentration.

  In addition, in the oxygen off-gas discharge flow path 503, branch introduction of oxygen off-gas from the upstream of the muffler 522 to the hydrogen diluter 424 and merging of the mixed gas downstream of the muffler 522 are intended. Since the muffler 522 causes a pressure loss with respect to the fluid (oxygen off-gas) passing through due to its structure, the pressure loss generates a differential pressure in the flow path before and after the muffler. In this embodiment, a differential pressure is generated between the branch location of the oxygen off-gas branch introduction flow path 505) and the merge location of the downstream flow path 407a so that the merge location is lowered. Therefore, the oxygen off gas can be reliably introduced into the mixing chamber 424 a of the hydrogen diluter 424 through the oxygen off gas branch introduction flow path 505 by this differential pressure. For this reason, it is possible to introduce oxygen off-gas without using special equipment, to simplify equipment configuration and control, and to reduce costs. In addition, since the mixing and passage of the gas in the mixing chamber 424a with an increased volume is achieved, a silencing effect can also be exhibited.

  Further, the joining point of the downstream flow path 407a in the oxygen off-gas discharge flow path 503 is the mixing portion 411 in the first and second embodiments described above. Therefore, in the third embodiment, the diluted hydrogen off-gas discharged from the hydrogen diluter 424 is mixed with the oxygen off-gas flowing through the oxygen off-gas discharge flow path 503 and further diluted to obtain a mixed gas. The concentration of hydrogen contained can be further reduced.

  As a result, also in this embodiment, the hydrogen off-gas can be exhausted to the atmosphere after the hydrogen concentration is reduced to a sufficiently low concentration that is effective for avoiding ignition. Therefore, the reliability of avoiding ignition can be increased.

  Also in this third embodiment, in order to ensure higher reliability, any one of the four methods described in the first embodiment is used to open the shut valve 414 to generate hydrogen. Off-gas is discharged.

  On the other hand, when an abnormality such as a failure of the pressure reducing valve 418 or 422 occurs, the pressure of the hydrogen gas supplied to the fuel cell 100 may become abnormally high. Therefore, in the present embodiment, a relief valve 415 is provided in the middle of the relief flow path 430 branched in the subsequent stage of the pressure reducing valve 418 in the main flow path 401, and in the middle of the relief flow path 409 branched in the subsequent stage of the pressure reducing valve 422. When the pressure of the hydrogen gas in the main flow path 401 from the pressure reducing valve 418 to the pressure reducing valve 422 rises to a predetermined value or more by providing the relief valve 416, the relief valve 415 is opened and the pressure reducing valve 422 When the pressure of the hydrogen gas in the main flow path 401 leading to the fuel cell 100 rises above a predetermined value, the relief valve 416 is opened, and the hydrogen gas is exhausted into the atmosphere outside the vehicle, so that the pressure of the hydrogen gas Is prevented from becoming excessive.

  When the high-pressure hydrogen gas tank 300 is filled with hydrogen gas, a hydrogen gas supply pipe (not shown) is connected to the hydrogen gas supply port 429 provided on the side surface of the vehicle and attached to the high-pressure hydrogen gas tank 300. By manually opening the filling manual valve 308, the high-pressure hydrogen gas supplied from the hydrogen gas supply pipe flows into the high-pressure hydrogen gas tank 300 through the supply flow path 432 and is filled therewith. At this time, a check valve 306 is provided at the base of the high-pressure hydrogen gas tank 300 so that the hydrogen gas filled in the high-pressure hydrogen gas tank 300 does not flow backward.

  Next, the gas discharge mechanism at the off-gas discharge port 524 employed in this embodiment will be described. FIG. 9 is an explanatory diagram for explaining the periphery of the off-gas exhaust port 524, and FIG. 10 is an explanatory diagram for explaining the periphery of the off-gas exhaust port 524 in relation to the vehicle body. As shown in the figure, the oxygen off-gas discharge channel 503 has a disc-shaped diffusion plate 530 facing the off-gas discharge port 524 at the end thereof. The diffusion plate 530 is fixed to the oxygen off-gas discharge channel 503 by a support arm 532.

  As shown in FIG. 10, the oxygen off-gas discharge channel 503 extends to the rear bumper B of the vehicle body S. When viewed from the side of the vehicle body, the diffusion plate 530 and the off-gas discharge port 524 are shielded by the bumper cart unit BS. is doing. A protector 536 is disposed so as to cover the off-gas discharge port 524 including the diffusion plate 530.

  The protector 536 is formed of a stainless steel plate in the shape of a dish through a perforated punching process such as a punching press, and is fixed to the main body of the oxygen offgas discharge channel 503 from the bumper cart part BS to the center of the vehicle body. In this embodiment, the protector 536 is fixed so as to maintain a constant distance from the off-gas discharge port 524 and the diffusion plate 530, and the hole diameter of the punch hole is about 5 mm. Further, the punch hole arrangement is such that the exhaust gas from the off-gas discharge port 524 can pass through without causing inadvertent gas retention, and the separation distance from the off-gas discharge port 524 and the diffusion plate 530 is set to the off-gas discharge port. It is assumed that the ignition source does not directly enter 524. The lower limit of the hole diameter of the punch hole may be any hole diameter that allows gas permeation and can be punched and pressed, and may be about 1-2 mm. The upper limit of the hole diameter may be a diameter (about 8 mm) that can substantially avoid direct entry of the ignition source into the off-gas discharge port 524.

  Since the diffusion plate 530 is provided in this way, in this embodiment, the gas discharged from the off-gas discharge port 524 collides with the diffusion plate 530 and is diffused in the opening diameter direction of the off-gas discharge port 524 and diffuses in all four directions. And mix with the atmosphere. For this reason, the contact opportunity between the exhaust gas (hydrogen off-gas) and the air around the end of the oxygen off-gas discharge channel 503 increases, and accordingly, the dilution of the exhaust gas (hydrogen off-gas) proceeds, and hydrogen is also discharged at the gas discharge location. The concentration can be quickly reduced. As a result, coupled with dilution by the hydrogen diluter 424 and dilution by the merge of the downstream flow path 407a, the hydrogen concentration can be more reliably reduced, and the reliability of ignition avoidance can be further increased. In this embodiment, the oxygen off-gas discharge channel 503 is made of stainless steel pipe having a tube diameter of about 40 mm, and the diffusion plate 530 having a diameter of about 100 to 150 mm is installed about 30 to 50 mm away from the end of the discharge channel.

  Further, since the off-gas discharge port 524 and the diffusion plate 530 are covered with the porous protector 536 and the above-described separation distance is secured, the ignition source can be prevented from directly entering the off-gas discharge port 524. . For this reason, the reliability of avoiding the ignition of the exhaust gas (hydrogen offgas) from the offgas discharge port 524 can be further enhanced in combination with the hydrogen concentration reduction by the hydrogen diluter 424 described above. In addition, pebbles and the like that have bounced off the tire collide with the protector 536, but do not reach the off-gas exhaust port 524 or the diffusion plate 530. Therefore, the flow path damage due to stepping stones can be avoided.

  In the above-described embodiment, the case where the diffusion plate 530 and the protector 536 are used together has been described. However, the diffusion plate 530 alone or the protector 536 may be provided. Moreover, in the protector 536, a mesh-shaped thing can also be shape | molded into a predetermined shape, and can also be installed in a bumper etc.

C. Variations:
The present invention is not limited to the above-described examples and embodiments, and can be implemented in various modes without departing from the scope of the invention.

  In the first and second embodiments described above, the present invention is applied to the fuel cell system using the hydrogen storage alloy tank 200 and the high-pressure hydrogen gas tank 300 as the hydrogen gas supply source. However, the present invention is not limited to these, and can also be applied to a fuel cell system using a reformer that reforms raw fuel to generate hydrogen gas as a hydrogen gas supply source. be able to.

  In the first and second embodiments described above, the hydrogen off-gas discharged from the fuel cell 100 is returned to the main flow path 401 to circulate the hydrogen gas. The present invention is not limited to a circulated type fuel cell system, and is also applied to a type of fuel cell system in which hydrogen off-gas discharged from the fuel cell 100 is discharged into the atmosphere as it is without circulating hydrogen gas. be able to.

  Further, the combustor 510 described in the second embodiment is provided downstream of the junction of the downstream flow path 407a and the oxygen off-gas discharge flow path 503 described in the third embodiment, so that the hydrogen concentration can be reduced by the hydrogen diluter 424. The hydrogen concentration reduction through the catalytic reaction by the combustor 510 can be used in combination.

  Further, in the third embodiment, the relief flow paths 430 and 409 are joined to the oxygen off-gas discharge flow path 503 at the ends thereof, or a hydrogen diluter 424 is provided in each relief flow path to provide hydrogen gas with oxygen off-gas. (Relief gas) can be mixed and diluted.

  Further, the diffusion plate 530 described in the third embodiment may be provided at the end of the relief flow paths 430 and 409 so that the hydrogen gas discharged from the flow paths is diffused in all directions and diluted. The diffusion plate 530 can be provided at the end of the oxygen off-gas discharge channel 503 described in the first and second embodiments.

  Further, the diffusion plate 530 described in the third embodiment is not limited to the installation on the end side of the oxygen off-gas discharge channel 503, and the diffusion plate 530 is disposed on the vehicle body side (for example, bumper, vehicle body frame, protector 536). Etc.) so as to face the off-gas discharge port 524 of the oxygen off-gas discharge channel 503.

  In the third embodiment, the hydrogen diluter 424 may include a mixing chamber 424a having a platinum catalyst 512 layer formed on the inner surface. In this way, in the hydrogen diluter 424, the mixing with the oxygen off-gas and the hydrogen removal by the catalytic reaction can occur simultaneously, so that the reduction of the hydrogen concentration can be ensured.

  In the third embodiment, the diffusion plate 530 is opposed to the off-gas discharge port 524 at the end of the oxygen off-gas discharge channel 503. However, the diffusion plate 530 can be modified as follows. FIG. 11 is an explanatory diagram for explaining a modified example of the oxygen off-gas discharge channel 503 and the diffusion plate 530.

  As shown in FIG. 11, the oxygen off-gas discharge channel 503 has an off-gas discharge port 524 extended in a trumpet shape. The diffusion plate 530 has a convex conical shape / conical truncated cone shape, and is disposed inside or outside the opening of the off-gas discharge port 524. Even in this case, it is possible to dilute the exhaust gas (hydrogen off-gas) and quickly reduce the hydrogen concentration through the diffusion of the exhaust gas in all directions. In this case, since the off-gas discharge port 524 is expanded in a trumpet shape, further gas diffusion can be achieved. As shown in FIG. 11, if the cylindrical body 531 is disposed outside the opening edge of the off-gas discharge port 524, the cylindrical body 531 and the off-gas discharge port 524 are opened along with the gas discharge from the off-gas discharge port 524. The ambient air from between the edges can enter the exhaust gas flow from the off-gas outlet 524. Therefore, the contact with the atmosphere is forcibly performed, and hydrogen dilution progresses accordingly, which is preferable.

  Further, in the third embodiment, the oxygen off gas is introduced into the hydrogen diluter 424 by a diversion from the oxygen off gas discharge channel 503 as shown in FIG. 7, but the oxygen off gas is forcibly used by using a pump or the like. It can also be introduced. This is preferable because the hydrogen off-gas dilution in the hydrogen diluter 424 is forced to proceed.

  Furthermore, the buffer 413 in the first embodiment can be modified as follows. FIG. 12 is an explanatory diagram for explaining a buffer 413 according to a modification. As shown in the figure, the buffer 413 of the modified example has a bellows-like side wall, and usually takes a shape in which the bellows is folded, and when the bellows extends, it returns to its original shape due to its own elastic force. Has been. Therefore, when hydrogen off gas from the shut valve 414 flows into such a buffer 413 (intermittent inflow due to valve on / off), the buffer 413 extends its bellows shape by gas inflow as shown by a two-dot chain line in the figure, and causes an increase in volume. The hydrogen off gas is retained. And since this buffer 413 mixes the hydrogen off gas which has been retained with the shape recovery by the elastic force into the downstream mixing unit 411, the mixing unit 411 can reliably dilute the hydrogen off gas with the oxygen off gas.

  Although the bellows-like buffer 413 is restored to its original shape by its own elastic force, it can be restored to its original shape by a spring, an actuator, or the like.

DESCRIPTION OF SYMBOLS 50 ... Control part 100 ... Fuel cell 102 ... Shut valve 104 ... Shut valve 200 ... Hydrogen storage alloy tank 202 ... Shut valve 300 ... High pressure hydrogen gas tank 302 ... Shut valve 304 ... Release manual valve 306 ... Check valve 308 ... Filling manual valve DESCRIPTION OF SYMBOLS 400 ... Pressure sensor 401 ... Main flow path 402 ... Shut valve 403 ... Circulation flow path 404 ... Pressure-reduction valve 405 ... Bypass flow path 406 ... Gas-liquid separator 407 ... Discharge flow path 408 ... Shut valve 409 ... Relief flow path 410 ... Pump 411 ... Mixing section 412 ... Shut valve 413 ... Buffer 414 ... Shut valve 416 ... Relief valve 418 ... Pressure reducing valve 420 ... Heat exchanger 422 ... Pressure reducing valve 424 ... Hydrogen diluter 425 ... Gas-liquid separator 426 ... Check valve 427 ... Check channel 428 ... Leak check boat 429 ... Hydrogen gas supply port 430 ... Relief channel 432 ... Supply channel 501 ... Oxidation gas supply channel 502 ... Air cleaner 503 ... Oxygen off gas discharge channel 504 ... Compressor 505 ... Oxygen off gas branch introduction Flow path 506 ... Humidifier 508 ... Gas-liquid separator 509 ... Pressure regulator 510 ... Combustor 512 ... Platinum catalyst 520 ... Gas-liquid separator 522 ... Muffler 524 ... Off-gas outlet 530 ... Diffusion plate 532 ... Support arm 536 ... Protector 601 ... Water circulation flow path 602 ... Pump 604 ... Humidified water tank 606 ... Pump 608 ... Injector B ... Rear bumper BS ... Bumpers cart part S ... Vehicle body

Claims (40)

In-vehicle fuel installed in a vehicle that is supplied with hydrogen gas and oxidant gas, and that uses these hydrogen gas and oxidant gas to generate electric power and has a fuel cell that discharges used hydrogen off-gas and oxygen off-gas. A battery system,
A first flow path connected to a hydrogen off-gas discharge port of the fuel cell and flowing the discharged hydrogen off-gas;
A second flow path connected to the oxygen off-gas discharge port of the fuel cell and flowing the discharged oxygen off-gas;
A mixing unit for guiding the discharged hydrogen offgas and the discharged oxygen offgas from the first flow path and the second flow path, respectively, and mixing the oxygen off gas with the hydrogen off gas;
A third flow path connected to the mixing section, for flowing the mixed gas and discharging the hydrogen off-gas into the atmosphere;
An in-vehicle fuel cell system comprising: The in-vehicle fuel cell system according to claim 1,
The mixing unit includes:
A vehicle-mounted fuel cell system formed to have a volume larger than that of the first and second flow paths for guiding off-gas. The in-vehicle fuel cell system according to claim 2,
The mixing unit includes:
An in-vehicle fuel cell system having a zigzag gas flow path. The in-vehicle fuel cell system according to any one of claims 1 to 3,
The mixing unit includes:
An oxygen off-gas branch introduction flow channel that branches off from the second flow channel and introduces the oxygen off-gas by diverting from the second flow channel;
The oxygen off-gas branch introduction flow path and the first flow path are connected, and the hydrogen off-gas and the oxygen off-gas are mixed, and then the mixing chamber is expanded in volume so as to flow into the third flow path.
The second flow path is
A vehicle-mounted fuel cell system that merges with the third flow path downstream from a branch point of the oxygen off-gas branch introduction flow path. The in-vehicle fuel cell system according to claim 4,
The in-vehicle fuel cell system, wherein the second flow path includes a pressure loss member that generates a pressure loss of the fluid passing between the branch point and the merge point with the third flow path. The in-vehicle fuel cell system according to claim 5,
The in-vehicle fuel cell system, wherein the pressure loss member is a muffler. The in-vehicle fuel cell system according to any one of claims 1 to 6,
A catalytic reaction unit disposed in a passage of the mixed gas in the mixing unit and reacting hydrogen and oxygen contained in the mixed gas with a catalyst to reduce a hydrogen concentration in the gas; In-vehicle fuel cell system provided. The in-vehicle fuel cell system according to claim 7,
The in-vehicle fuel cell system, wherein the catalyst reaction part is a catalyst layer formed on the inner surface of the mixing part. The in-vehicle fuel cell system according to any one of claims 1 to 6,
A catalytic reaction unit arranged in a passage for the mixed gas after the mixing unit and reacting hydrogen and oxygen contained in the mixed gas with a catalyst to reduce a hydrogen concentration in the gas; An in-vehicle fuel cell system further provided. The in-vehicle fuel cell system according to any one of claims 7 to 9,
An in-vehicle fuel cell system further comprising a gas-liquid separator that removes a liquid component of moisture contained in the gas in a gas flow path to the catalyst reaction section. The in-vehicle fuel cell system according to any one of claims 1 to 10,
Furthermore,
A hydrogen gas flow path for supplying hydrogen gas from a hydrogen gas supply source to the fuel cell;
A relief passage that branches off from the hydrogen gas passage and discharges the hydrogen gas from the hydrogen gas passage when the pressure of the hydrogen gas passage is abnormal.
A vehicle-mounted fuel cell system that mixes and dilutes hydrogen gas flowing through the relief flow path with the oxygen off-gas flowing through the second flow path. The in-vehicle fuel cell system according to claim 11,
The in-vehicle fuel cell system, wherein the relief flow path merges with the second flow path. The in-vehicle fuel cell system according to claim 11,
The relief flow path is provided with a catalyst reaction section that reacts hydrogen and oxygen contained in the mixed gas with a catalyst to reduce the hydrogen concentration in the gas, and the catalyst reaction section flows through the second flow path. In-vehicle fuel cell system that guides oxygen off-gas. The in-vehicle fuel cell system according to any one of claims 1 to 13,
An in-vehicle fuel cell system further comprising a valve disposed in the first flow path and capable of passing and blocking the hydrogen off-gas to and from the mixing unit by opening and closing. The in-vehicle fuel cell system according to claim 14,
A fourth flow path connected to the hydrogen gas supply port of the fuel cell and flowing the supplied hydrogen gas;
Connecting the first location between the outlet of the fuel cell and the valve in the first flow path and the second location in the fourth flow path, from the fuel cell; A fifth flow path for flowing the discharged hydrogen off-gas and returning it to the fourth flow path;
An in-vehicle fuel cell system further comprising: The in-vehicle fuel cell system according to claim 14 or 15,
A sixth flow path connected to the oxidizing gas supply port of the fuel cell and flowing the supplied oxidizing gas;
A flow rate variable unit arranged in the second flow path or the sixth flow path and capable of changing a flow rate of the discharged oxygen off-gas;
A control unit for controlling the valve and the flow rate variable unit;
Further comprising
The controller is configured to increase the flow rate of the oxygen off-gas discharged by the flow rate variable unit from a predetermined flow rate when the valve is opened. The in-vehicle fuel cell system according to claim 14 or 15,
A sixth flow path connected to the oxidizing gas supply port of the fuel cell and flowing the supplied oxidizing gas;
A flow rate variable unit arranged in the second flow path or the sixth flow path and capable of changing a flow rate of the discharged oxygen off-gas;
A control unit for controlling the valve and the flow rate variable unit;
Further comprising
The in-vehicle fuel cell system, wherein the control unit opens the valve when the flow rate of the oxygen off gas discharged by the flow rate variable unit exceeds a predetermined flow rate. The in-vehicle fuel cell system according to claim 14 or 15,
A control unit for controlling the valve;
The control unit causes the valve to repeatedly open and close at a relatively short period when sending the discharged oxygen off gas to the mixing unit. The in-vehicle fuel cell system according to claim 14 or 15,
The apparatus further includes a flow rate reduction unit that is disposed between the valve and the mixing unit in the first flow path, and sends the hydrogen off-gas flowing from the valve to the mixing unit while reducing the flow rate thereof. In-vehicle fuel cell system. The in-vehicle fuel cell system according to claim 19,
The flow rate reducing portion includes a hollow portion having a large volume at an intermediate portion between the inlet and outlet of the hydrogen off gas, and the hydrogen off gas flowing in from the valve is retained in the hollow portion and then discharged. An on-vehicle fuel cell system that sends the hydrogen off-gas flowing in from the valve to the mixing unit while reducing the flow rate thereof. The in-vehicle fuel cell system according to claim 20,
The flow rate reducing unit is an in-vehicle fuel cell system having the outlet having a diameter narrowed from the diameter of the outlet. The in-vehicle fuel cell system according to claim 19 or 20,
The hollow part of the flow rate reducing part is an in-vehicle fuel cell system having a variable volume. The in-vehicle fuel cell system according to claim 22,
The hollow part of the flow rate reduction part is a vehicle-mounted fuel cell system that causes an increase in volume when the hydrogen off-gas flows from the valve. The in-vehicle fuel cell system according to any one of claims 1 to 23,
A vehicle-mounted fuel cell system having a diffusion member that diffuses a gas flow flowing out from an end opening of the flow path in an opening radial direction at an end of the third flow path. In-vehicle fuel installed in a vehicle that is supplied with hydrogen gas and oxidant gas, and that uses these hydrogen gas and oxidant gas to generate electric power and has a fuel cell that discharges used hydrogen off-gas and oxygen off-gas. A battery system,
A vehicle-mounted fuel cell system having a diffusion member for diffusing a gas flow flowing out from an end opening of the flow path in an opening radial direction at the end of a flow path for discharging the hydrogen off gas or a gas containing the off gas into the atmosphere. The in-vehicle fuel cell system according to claim 24 or claim 25,
The in-vehicle fuel cell system, wherein the diffusing member is disposed to face the flow path end with a predetermined distance. The in-vehicle fuel cell system according to claim 26,
The diffusion member is an in-vehicle fuel cell system having a conical shape having a sloped side surface. The in-vehicle fuel cell system according to any one of claims 24 to 27,
The in-vehicle fuel cell system, wherein the diffusion member is installed either on the end of the flow path or on the vehicle body side of the vehicle. The in-vehicle fuel cell system according to claim 24 or claim 25,
A vehicle-mounted fuel cell system comprising a shielding member that covers the end of the flow path including the diffusion member at a predetermined distance, and the shielding member has a hole for discharging exhaust gas from the end of the flow path . The in-vehicle fuel cell system according to any one of claims 1 to 23,
A vehicle-mounted vehicle having a shielding member at the end of the third flow path so as to cover the end with a predetermined distance, and the shielding member has a hole for discharging exhaust gas from the end of the third flow path. Fuel cell system. In-vehicle fuel installed in a vehicle that is supplied with hydrogen gas and oxidant gas, and that uses these hydrogen gas and oxidant gas to generate electric power and has a fuel cell that discharges used hydrogen off-gas and oxygen off-gas. A battery system,
A shielding member is provided at the end of the flow path for discharging the hydrogen off gas or the gas containing this off gas to the atmosphere, and covers the end with a predetermined distance, and the shielding member includes the third flow path. Vehicle-mounted fuel cell system having a hole for discharging exhaust gas from the end of the vehicle. The in-vehicle fuel cell system according to any one of claims 29 to 31,
The shielding member is an in-vehicle fuel cell system installed in a bumper. The in-vehicle fuel cell system according to any one of claims 29 to 32,
The in-vehicle fuel cell system, wherein the shielding member has a mesh shape or a porous punch shape. In a fuel cell that receives supply of hydrogen gas and oxidizing gas, generates power using these hydrogen gas and oxidizing gas, and exhausts used hydrogen off-gas and oxygen off-gas, the discharged hydrogen off-gas is discharged into the atmosphere. A hydrogen off-gas discharge method
(A) mixing the hydrogen offgas discharged from the fuel cell with the discharged oxygen offgas;
(B) discharging the mixed gas into the atmosphere;
A method for discharging hydrogen off-gas. The hydrogen off-gas discharge method according to claim 34,
The step (a)
Introducing the hydrogen offgas discharged from the fuel cell from the first flow path through which the offgas flows into a mixing chamber having an enlarged volume (a1);
Introducing the oxygen off-gas discharged from the fuel cell into the mixing chamber from a branch channel branched from a second channel through which the off-gas flows;
Discharging the gas mixed in the mixing chamber to a third flow path connected to the mixing chamber,
The step (b)
A hydrogen off-gas discharge method comprising a step of joining the second flow path to the third flow path and discharging the gas to the atmosphere downstream from a branching point of the branch flow path in the second flow path . The hydrogen off-gas discharge method according to claim 34,
The step (b)
Reacting hydrogen and oxygen contained in the mixed gas with a catalyst to reduce the hydrogen concentration in the gas;
Discharging the gas with reduced hydrogen concentration into the atmosphere;
A hydrogen off-gas discharge method including: The hydrogen off-gas discharge method according to claim 34 or claim 36,
The step (a)
A hydrogen off-gas exhausting method including a step of increasing a flow rate of the oxygen off-gas discharged from the fuel cell from a predetermined flow rate when the hydrogen off-gas is mixed with the oxygen off-gas. The hydrogen off-gas discharge method according to claim 34 or claim 36,
The step (a)
A hydrogen off-gas discharge method comprising a step of mixing the hydrogen off-gas with the oxygen off-gas when the flow rate of the oxygen off-gas discharged from the fuel cell exceeds a predetermined flow rate. The hydrogen off-gas discharge method according to claim 34 or claim 36,
The step (a)
A method for discharging hydrogen offgas, comprising the step of mixing the hydrogen offgas with the oxygen offgas at discrete timings having a relatively short period. The hydrogen off-gas discharge method according to claim 34 or claim 36,
The step (a)
Reducing the flow rate of the hydrogen off-gas discharged from the fuel cell;
Mixing the hydrogen off-gas having a reduced flow rate with the oxygen off-gas;
A hydrogen off-gas discharge method including:

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