JP2009048945A - Fuel cell system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel cell system capable of suitably supplying a fuel gas to respective fuel gas flow passages of a unit cell. <P>SOLUTION: The fuel cell system comprises a fuel cell stack 10 constituted of the unit cells 20 having an anode flow passages 26 laminated in a plurality of numbers, and having, in its inside and its laminating direction, an interior hydrogen supply manifold 11 to distribute and supply hydrogen to the anode flow passages 26 of the respective unit cells 20 and an interior hydrogen discharge manifold 12 to collect and discharge hydrogen from the anode flow passages 26 of the respective unit cells 20, wherein the interior hydrogen supply manifold 11 opens to the outside at a first hydrogen introducing port 11a of its one end side and a second hydrogen introducing port 11b of its other end side; a first fuel gas supply flow passage to connect a hydrogen tank 31 and the first hydrogen introducing port 11a; a second fuel gas supply flow passage which is branched from the first fuel gas supply flow passage and connected to the second hydrogen introducing port 11b; and an assist introducing valve 34 and a variable orifice 35 to control a flow rate of a gas to flow into the second fuel gas supply flow passage. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a fuel cell system including a fuel cell stack.

  In recent years, a polymer electrolyte fuel cell (Polymer Electrolyte Fuel Cell) that generates electricity by generating an electrochemical reaction by supplying hydrogen (fuel gas) to the anode and air containing oxygen (oxidant gas) to the cathode. Fuel cells such as PEFC) have attracted attention.

  However, since the generated power per fuel cell (which is referred to as a single cell) is small, a fuel cell stack configured by stacking a plurality of single cells and connecting a plurality of single cells in series is usually used. used. In such a fuel cell stack, an internal hydrogen supply manifold (internal fuel gas supply flow path) communicating with, for example, the anode flow path of each single cell is formed in the stacking direction inside the fuel cell stack. Hydrogen is supplied to the anode flow path of each single cell through the supply manifold.

  On the other hand, even if such a fuel cell stack is not connected to an external circuit, if hydrogen and air exist on both sides of a MEA (Membrane Electrode Assembly) constituting a single cell, OCV (Open Circuit Voltage: open circuit voltage). If the fuel cell stack is left for a long time with CV being generated in this way, for example, a current flows in the single cell, and the single cell may deteriorate.

In view of this, there has been proposed a technique in which, when power generation of a fuel cell stack is stopped, hydrogen present in the fuel cell stack and water vapor are discharged from the viewpoint of preventing freezing during the stop, and air is sealed in the fuel cell stack.
Then, at the next power generation start, it is necessary to discharge air (including nitrogen) enclosed in the anode flow path from the fuel cell stack and promote replacement / filling with hydrogen so that the fuel cell stack can generate power. Yes (see Patent Document 1).

JP 2004-193107 A

However, in the conventional fuel cell stack, the internal hydrogen supply manifold extending in the stacking direction is open to the outside only at one end side in the stacking direction, so that the internal hydrogen supply manifold extends through the one opening (hydrogen supply port). Hydrogen is supplied to the hydrogen supply manifold and then supplied to the anode channel of each single cell.
Accordingly, hydrogen is supplied quickly to the anode flow path of the single cell close to the one opening, but it is difficult to supply hydrogen to the anode flow path of the single cell far from the one opening. The hydrogen concentration in the inside tends to be uneven. As a result, there is a problem that it takes time until the inside of the fuel cell stack is increased to an appropriate hydrogen concentration.

  Therefore, an object of the present invention is to provide a fuel cell system capable of suitably supplying fuel gas to each fuel gas flow path of a single cell constituting a fuel cell stack.

  As means for solving the above-mentioned problems, the present invention comprises a plurality of unit cells each having a fuel gas flow path for supplying and discharging fuel gas to and from the anode of the membrane electrode assembly. An internal fuel gas supply channel for distributing and supplying fuel gas to the fuel gas channel of each single cell in the stacking direction, and an internal fuel gas discharge flow for collecting and discharging the fuel gas from the fuel gas channel of each single cell A fuel cell stack that is open to the outside at a first fuel gas introduction port on one end side and a second fuel gas introduction port on the other end side. A first fuel gas supply channel connecting the fuel gas source and the first fuel gas inlet, and a second fuel branched from the first fuel gas supply channel and connected to the second fuel gas inlet A gas supply passage and a gas flowing through the second fuel gas supply passage. And flow control means for controlling the flow rate of a fuel cell system comprising: a.

According to such a fuel cell system, for example, when the fuel gas flow path is replaced with the fuel gas at the time of starting the system, or the power generation demand for the fuel cell stack becomes large, When a high flow rate of fuel gas is to be supplied to the flow path, the flow rate control means increases the flow rate of the fuel gas flowing through the second fuel gas supply flow path.
Then, the fuel gas is supplied to the internal fuel gas supply channel via the first fuel gas inlet and the second fuel gas inlet. That is, the fuel gas is supplied from both sides toward the center to the internal fuel gas supply channel, flows in the stacking direction, is supplied to the fuel gas channel of each single cell substantially uniformly, and the hydrogen in the fuel cell stack The concentration is likely to rise almost evenly.
In this way, fuel gas can be supplied from both sides of the internal fuel gas supply flow path, and fuel gas can be supplied to each fuel gas flow path, so that it is possible to prevent rapid replacement with fuel gas or fuel gas shortage. it can.

  An ejector disposed in the first fuel gas supply flow path; a circulation flow path for returning the gas discharged from the internal fuel gas discharge flow path to the first fuel gas supply flow path via the ejector; , And the upstream end of the second fuel gas supply flow path is connected to the first fuel gas supply flow path upstream of the ejector.

According to such a fuel cell system, the gas containing unconsumed fuel gas discharged from the internal fuel gas discharge flow path can be returned to the first fuel gas supply flow path by the circulation flow path. Consumption can be reduced.
Since the upstream end of the second fuel gas supply channel is connected to the first fuel gas supply channel upstream of the ejector, the fuel returned to the first fuel gas supply channel via the circulation channel Water vapor accompanying the gas is less likely to flow into the second fuel gas supply channel. As described above, since the water vapor hardly flows into the second fuel gas supply channel, the second fuel gas supply channel is difficult to freeze.

  The anode of the membrane electrode assembly is configured by stacking a plurality of single cells each having a fuel gas flow path for supplying and discharging fuel gas, and the fuel gas of each single cell is formed in the stack direction. An internal fuel gas supply flow path for distributing and supplying fuel gas to the flow path; and an internal fuel gas discharge flow path for collecting and discharging fuel gas from the fuel gas flow paths of the single cells. The path is connected to the fuel cell stack that opens to the outside at the first fuel gas discharge port on one end side and the second fuel gas discharge port on the other end side, and the first fuel gas discharge port, The internal fuel gas is connected to the first fuel gas discharge flow path through which the fuel gas from the internal fuel gas discharge flow path and the second fuel gas discharge port are connected, and is connected to the first fuel gas discharge flow path. The fuel gas from the discharge channel is discharged into the first fuel gas discharge A second fuel gas discharge channel for combining the flow path, a fuel cell system characterized by comprising a flow control means for controlling the flow rate of gas flowing through the second fuel gas discharge channel.

  According to such a fuel cell system, for example, when the fuel gas flow path is replaced with the fuel gas at the time of starting the system, or the power generation demand for the fuel cell stack becomes large, When a high flow rate fuel gas is to be supplied to the flow path, the flow rate control means increases the flow rate of the gas flowing through the discharge flow path as the second fuel gas. Then, the gas in the internal fuel gas discharge channel is discharged to the outside through the first fuel gas discharge port and the second fuel gas discharge port. That is, the gas in the internal fuel gas discharge channel is quickly discharged to the outside from both sides.

Therefore, the gas in each fuel gas passage is substantially uniform and is easily discharged to the internal fuel gas discharge passage. Therefore, it becomes easy for fuel gas to flow promptly from the internal fuel gas supply channel into each fuel gas channel.
In this way, fuel gas can be supplied from both sides of the internal fuel gas supply flow path, and fuel gas can be supplied to each fuel gas flow path, so that it is possible to prevent rapid replacement with fuel gas or fuel gas shortage. it can.

  Further, in the case where the start of the fuel cell stack is instructed, when the fuel gas flow paths are replaced with fuel gas, the flow rate control means controls the gas to flow through the inside thereof. It is a fuel cell system.

  According to such a fuel cell system, when the activation of the fuel cell stack is instructed, when replacing each fuel gas flow path with the fuel gas, the flow rate control means controls the gas to flow therethrough. The fuel gas can be quickly supplied to each fuel gas channel, and can be quickly replaced with the fuel gas. Thereby, the time required for replacement of the fuel gas at the time of starting the system can be shortened.

  The fuel cell stack further includes a concentration detection means for detecting a fuel gas concentration in the fuel cell stack, and the flow rate control means passes through the inside so that the fuel gas concentration detected by the concentration detection means becomes a predetermined fuel gas concentration. A fuel cell system that controls a flow rate of gas.

  According to such a fuel cell system, the flow rate control means is arranged so that the concentration detected by the concentration detection means becomes a predetermined fuel gas concentration (in the embodiments described later, reference hydrogen concentrations C0 and C1). The flow rate of the gas passing through can be controlled.

  ADVANTAGE OF THE INVENTION According to this invention, the fuel cell system which can supply fuel gas suitably to each fuel gas flow path of the single cell which comprises a fuel cell stack can be provided.

  Hereinafter, an embodiment of the present invention will be described with reference to FIGS.

≪Configuration of fuel cell system≫
A fuel cell system 1 shown in FIG. 1 is mounted on a fuel cell vehicle (mobile body) (not shown). The fuel cell system 1 includes a fuel cell stack 10, hydrogen sensors 18 and 19 (concentration detection means) for detecting the hydrogen concentration in the fuel cell stack 10, and hydrogen (fuel gas, reaction) with respect to the anode of the fuel cell stack 10. Gas), a cathode system that supplies and discharges oxygen-containing air (oxidant gas, reaction gas) to the cathode of the fuel cell stack 10, and a scavenging gas (from the cathode system to the anode system during scavenging) A scavenging system for guiding non-humidified air), an IG 61 (ignition), and an ECU 70 (Electronic Control Unit) for electronically controlling them are provided.

<Fuel cell stack>
As shown in FIG. 2, the fuel cell stack 10 has a somewhat vertically long rectangular parallelepiped shape, and includes a plurality of (for example, 200 to 400) single cells 20 and two end plates 16 and 16. Yes. As shown in FIGS. 2 and 3, the plurality of single cells 20 are stacked in the thickness direction and electrically connected in series, and the end plate 16 includes the stacked single cells 20. , Sandwiched from both outsides.

[Single cell]
The single cell 20 is a polymer electrolyte fuel cell, and is arranged on the MEA 21 having the electrolyte membrane 22 sandwiched between the anode 23 and the cathode 24, the anode separator 25 disposed on the anode 23 side, and the cathode 24 side. A cathode separator 27. The anode separator 25 and the cathode separator 27 sandwich the MEA 21.

The electrolyte membrane 22 is composed of, for example, a monovalent cation exchange membrane.
The anode 23 and the cathode 24 are made of a conductive porous material such as carbon paper, and contain a catalyst (Pt, Ru, etc.) for causing a reaction in the anode 23 and the cathode 24.

The anode separator 25 is a plate-like component that supplies and discharges hydrogen to and from the anode 23. As shown in FIG. 4, a groove-like anode flow path 26 (fuel gas flow) through which hydrogen flows is provided on the side of the anode 23. A plurality of roads are formed.
The plurality of anode flow paths 26 extend in the vertical direction so that hydrogen from the internal hydrogen supply manifold 11 described later flows vertically downward through the anode flow paths 26 and flows into the internal hydrogen discharge manifold 12 described later. It has become. In addition, since the anode channel 26 extends in the vertical direction as described above, even if condensed water is generated in the anode channel 26, the condensed water is discharged to the internal hydrogen discharge manifold 12 by its own weight. It has become.

The cathode separator 27 is a plate-like component that supplies and discharges air to and from the cathode 24, and a plurality of groove-like cathode channels 28 (oxidant gas channels) through which air flows are formed on the side surfaces of the cathode 24. (See FIG. 3).
The plurality of cathode flow paths 28 extend in the vertical direction so that air from the internal air supply manifold 13 described later flows vertically downward through the cathode flow paths 28 and flows into the internal air discharge manifold 14 described later. It has become. Further, since the cathode channel 28 extends in the vertical direction in this way, discharge of generated water and the like in the cathode channel 28 is promoted.

  A coolant channel (not shown) is formed on at least one of the back surface of the anode separator 25 (side surface of the adjacent single cell 20) and the back surface of the cathode separator 27 (side surface of the adjacent single cell 20). The fuel cell stack 10 is appropriately cooled by allowing the refrigerant to flow through the refrigerant flow path of each single cell 20.

[Internal hydrogen supply manifold]
The fuel cell stack 10 has an internal hydrogen supply manifold 11 (internal fuel gas supply flow path) in the inside thereof, specifically in the upper right part of FIG. The internal hydrogen supply manifold 11 is configured by overlapping through holes formed in the electrolyte membrane 22, the anode separator 25, the cathode separator 27, and the end plates 16 and 16, and extends in the stacking direction of the single cells 20. The internal hydrogen supply manifold 11 includes a first hydrogen inlet 11a (first fuel gas inlet) on the front side (one end side) and a second hydrogen inlet 11b (second fuel) on the rear side (the other end side). Gas opening) and open to the outside.

  Further, the internal hydrogen supply manifold 11 communicates with the anode flow path 26 of each single cell 20 (see FIG. 4). The internal hydrogen supply manifold 11 distributes and supplies hydrogen flowing into the interior from the outside to the anode flow paths 26.

[Internal hydrogen discharge manifold]
The fuel cell stack 10 has an internal hydrogen discharge manifold 12 (internal fuel gas discharge flow path) in the inside thereof, specifically in the lower left part of FIG. Similar to the internal hydrogen supply manifold 11, the internal hydrogen discharge manifold 12 is configured by overlapping through holes formed in the anode separator 25 and the like, and extends in the stacking direction. The internal hydrogen discharge manifold 12 includes a first hydrogen discharge port 12a (first fuel gas discharge port) on the front side (one end side) and a second hydrogen discharge port 12b (second fuel side) on the rear side (the other end side). Gas outlet) and open to the outside.

  Further, the internal hydrogen discharge manifold 12 communicates with the anode flow path 26 of each single cell 20 (see FIG. 4). The internal hydrogen discharge manifold 12 collects hydrogen from each anode flow path 26 (this is referred to as anode off gas) and discharges it to the outside.

[Internal air supply manifold]
The fuel cell stack 10 has an internal air supply manifold 13 (internal oxidant gas supply flow path) in the interior thereof, specifically in the upper left part of FIG. Similar to the internal hydrogen supply manifold 11, the internal air supply manifold 13 is configured by overlapping through holes formed in the anode separator 25 and the like, and extends in the stacking direction. The internal air supply manifold 13 is opened to the outside at the front air inlet 13a.

  The internal air supply manifold 13 communicates with the cathode flow path 28 of each single cell 20. The internal air supply manifold 13 distributes and supplies the air flowing into the cathode from the outside to the cathode channels 28.

[Internal air discharge manifold]
The fuel cell stack 10 has an internal air discharge manifold 14 (internal oxidant gas discharge passage) in the inside thereof, specifically in the lower right part of FIG. Similar to the internal hydrogen supply manifold 11, the internal air discharge manifold 14 is configured by overlapping through holes formed in the anode separator 25 and the like, and extends in the stacking direction. The internal air discharge manifold 14 opens to the outside at the front air discharge port 14a.

  Further, the internal air discharge manifold 14 communicates with the cathode flow path 28 of each single cell 20. The internal air discharge manifold 14 collects air that flows into each cathode flow path 28 (referred to as “cathode off gas”) and discharges the air to the outside.

  Then, when hydrogen is supplied to each anode 23 via the anode flow path 26 and air is supplied to each cathode 24 via the cathode flow path 28, an electrode reaction occurs and OCV is generated in each single cell 20. It is like that. Next, in a state where the OCV is equal to or higher than the predetermined OCV, when there is a power generation request and current is taken out to an external circuit (not shown) including a travel motor and the like, the fuel cell stack 10 generates power.

<Hydrogen sensor>
Returning to FIG. 1, the description will be continued.
The hydrogen sensors 18 and 19 are incorporated in the fuel cell stack 10 and detect the hydrogen concentration in the anode flow path 26. The hydrogen sensor 18 is arranged so as to detect the hydrogen concentration C11 of the anode channel 26 slightly closer to the first hydrogen introduction port 11a (slightly in front, see FIG. 3) in the stacking direction. On the other hand, the hydrogen sensor 19 is arranged so as to detect the hydrogen concentration C12 of the anode channel 26 slightly closer to the second hydrogen inlet 11b (slightly rear side, see FIG. 3).

The hydrogen sensors 18 and 19 are connected to the ECU 70, and the detected hydrogen concentrations C11 and C12 are output to the ECU 70, respectively. In addition, it is preferable to arrange | position the position of the hydrogen sensors 18 and 19 in a lamination direction in the position where it is hard to introduce | transduce hydrogen, or the position where hydrogen is hard to discharge | emit based on a preliminary test etc., for example.
However, the number and position of the hydrogen sensors 18 and 19 are not limited to this, and may be changed as appropriate.

<Anode system>
The anode system is a system for supplying and discharging hydrogen to and from the anode flow path 26, and includes a hydrogen tank 31 (fuel gas source), a shut-off valve 32, an ejector 33, an assist introduction valve 34 (flow rate control means), A variable orifice 35 (flow rate control means), a purge valve 36, a check valve 37, an assist discharge valve 38 (flow rate control means), and a variable orifice 39 (flow rate control means) are provided.

The hydrogen tank 31 is connected to the first hydrogen inlet 11a via a pipe 31a, a shutoff valve 32, a pipe 32a, an ejector 33, and a pipe 33a. When the shutoff valve 32 is opened by the ECU 70, hydrogen is supplied from the hydrogen tank 31 to the internal hydrogen supply manifold 11 and the anode flow path 26 through the first hydrogen inlet 11a. . A pressure reducing valve (not shown) is provided downstream of the shut-off valve 32 so that hydrogen is depressurized to a predetermined pressure.
Here, the first fuel gas supply passage (first fuel gas supply pipe) connecting the hydrogen tank 31 (fuel gas source) and the first hydrogen inlet 11a is configured to include pipes 31a, 32a, and 33a. ing. In addition to the hydrogen tank 31, for example, a hydrogen storage alloy that stores hydrogen may be used as the fuel gas source.

The middle of the pipe 32a upstream from the ejector 33 is connected to the second hydrogen inlet 11b via a pipe 34a, an assist introduction valve 34, a pipe 34b, a variable orifice 35, and a pipe 35b.
Therefore, when the assist introduction valve 34 is opened by the ECU 70 while the shutoff valve 32 is opened and the variable orifice 35 is appropriately controlled, the hydrogen is supplied to the internal hydrogen supply manifold via the second hydrogen introduction port 11b. 11 and the anode channel 26, and the introduction of hydrogen into the anode channel 26 is assisted.
That is, the fuel cell stack 10 is designed so that hydrogen can be supplied to the inside from both ends in the stacking direction of the fuel cell stack 10.

  As will be described later, when the system is stopped, the anode flow path 26 is scavenged and replaced with air, the assist introduction valve 34 is opened, and the variable orifice 35 is appropriately controlled so that the scavenging gas (air ) Is introduced from both ends of the fuel cell stack 10 to push out residual hydrogen and water vapor so that they can be quickly scavenged.

  Here, the second fuel gas supply channel (second fuel gas supply piping) branched from the first fuel gas supply channel and connected to the second fuel gas introduction port (second hydrogen introduction port 11b) is a pipe 34a. , 34b, 35a.

  Since the upstream end of the pipe 34a constituting the second fuel gas supply flow path is connected to the pipe 32a upstream of the ejector 33, the anode off gas is returned to the ejector 33 as described later. Water vapor accompanying the off gas is less likely to flow into the pipe 34a. This prevents the pipes 34a, 34b, and 35a from freezing.

  Further, the second fuel gas supply flow path constituted by the pipes 34a, 34b, 35a and the like is used for special cases such as hydrogen replacement at the time of starting the system and scavenging at the time of stopping the system. It can also be configured with a small-diameter pipe with respect to the pipe 32a and the like constituting the first fuel gas supply channel. And if it is such a structure, a system structure can be simplified.

  The first hydrogen discharge port 12a is connected via a pipe 36a and a purge valve 36 to a pipe 36b whose downstream end communicates with the outside. In the middle of the pipe 36a, the pipe 36c is connected to the ejector 33. Further, the pipe 36c is provided with a check valve 37 (backflow prevention means) that allows gas to flow only to the ejector 33. It has been.

The purge valve 36 is a normally closed valve. When the purge valve 36 is closed, the purge valve 36 is discharged through the first hydrogen discharge port 12a, and the anode off gas containing unreacted hydrogen is returned to the ejector 33. ing. As a result, hydrogen circulates and the use efficiency of hydrogen is enhanced.
Therefore, the circulation flow path (circulation pipe) includes a part of the pipe 36a and the pipe 36c.

  On the other hand, when impurities (water vapor, nitrogen, etc.) accompanying the circulating hydrogen increase and the voltage of the single cell 20 detected via a cell voltage monitor (not shown) decreases, the anode flow path 26 is activated when the system is started. Is replaced with hydrogen, the purge valve 36 is opened by the ECU 70 when the anode passage 26 is replaced with air (scavenging gas) when the system is stopped.

When the purge valve 36 is thus opened, the gas in the anode flow path 26 and the internal hydrogen discharge manifold 12 is discharged to the outside through the first hydrogen discharge port 12a and the pipes 36a and 36b. ing.
Therefore, the first fuel gas discharge channel (first fuel gas discharge pipe) is configured to include the pipes 36a and 36b.

The second hydrogen discharge port 12b is connected to the pipe 36b via the pipe 38a, the assist discharge valve 38, the pipe 38b, the variable orifice 39, and the pipe 39a.
When the above-described hydrogen is replaced or the air is replaced by the ECU 70, the assist discharge valve 38 is opened and the variable orifice 39 is appropriately controlled. The gas is discharged to the outside through the second hydrogen discharge port 12b, the pipe 38a, and the pipe 39a.
In other words, the gas in the anode channel 26 is designed to be discharged from both ends in the stacking direction of the fuel cell stack 10 to the outside.

Here, the second fuel gas discharge channel (second fuel gas discharge pipe) includes pipes 38a, 38b, and 39a.
The second fuel gas supply flow path constituted by the pipes 34a, 34b, 35a and the like is used for special cases such as hydrogen replacement at the time of starting the system and scavenging at the time of system stop. It can also be configured with a small-diameter pipe with respect to the pipe 36a and the like constituting the first fuel gas discharge channel. And if it is such a structure, a system structure can be simplified.

<Cathode system>
The cathode system includes a compressor 41.
The compressor 41 is connected to the air inlet 13a via the pipe 41a. When the compressor 41 operates according to a command from the ECU 70, air is supplied to the cathode flow path 28 via the air inlet 13a and the internal air supply manifold 13. The pipe 41a is provided with a humidifier (not shown) so that the air supplied to the fuel cell stack 10 is appropriately humidified.

  The air discharge port 14a is connected to a pipe 41b whose downstream end is open to the outside. The cathode off-gas from the cathode channel 28 merges with the pipe 36b (not shown) via the internal air discharge manifold 14, the air discharge port 14a, and the pipe 41b, and dilutes hydrogen from the anode system while It is supposed to be discharged.

<Scavenging system>
The scavenging system includes a normally closed scavenging valve 51 (scavenging means). The middle of the pipe 41a is connected to the pipe 32a via the pipe 51a, the scavenging valve 51, and the pipe 51b. The pipe 51b is connected to the pipe 32a on the upstream side of the connection position of the pipe 34a.

When the scavenging valve 51 is opened by the ECU 70 while the compressor 41 is operating, the scavenging gas (non-humidified air) is guided to the pipe 32a. In this case, when the assist introduction valve 34 is opened and the variable orifice 35 is appropriately controlled, the scavenging gas is supplied to the internal hydrogen supply manifold 11 via the first hydrogen introduction port 11a and the second hydrogen introduction port 11b. It is supplied from both sides.
Note that scavenging means pushing out water vapor, residual hydrogen, etc. in the fuel cell stack 10 to the outside, and scavenging gas is gas introduced into the fuel cell stack 10 in order to perform scavenging.

<Other equipment>
The IG 61 is a start switch for the fuel cell vehicle and the fuel cell system 1 and is provided around the driver's seat. Moreover, IG61 is connected with ECU70, ECU70 detects the ON / OFF signal of IG61.

  An accelerator pedal 62 (Accelerator Pedal: AP) is a pedal that the driver steps on in response to a travel request, and is disposed at the foot of the driver's seat. Then, the accelerator pedal 62 sends a signal based on the degree of depression to the ECU 70. The ECU 70 detects the amount of depression of the accelerator pedal 62, and recognizes a power generation request from the driver according to the amount of depression. .

<ECU>
The ECU 70 is a control device that electronically controls the fuel cell system 1 and includes a CPU, a ROM, a RAM, various interfaces, an electronic circuit, and the like, and executes various processes according to programs stored therein. It is supposed to be. Specific processing of the ECU 70 and the operation of the fuel cell system 1 by this will be described later.

≪Operation and effect of fuel cell system at system startup≫
With reference to FIG. 5, the operation | movement and effect at the time of starting of the fuel cell system 1 are demonstrated.
Before starting, the anode flow path 26, the cathode flow path 28, the internal hydrogen supply manifold 11, the internal hydrogen discharge manifold 12, the internal air supply manifold 13, and the internal air discharge manifold 14 are connected to the OCV when the system is stopped. In order to prevent the occurrence, air is enclosed by scavenging when the system is stopped, which will be described later. In addition, it is possible to temporarily store whether or not the fuel cell stack 10 has been scavenged by a flag or the like, and perform the following processing only when scavenging is performed before the system is started and air is sealed. Also good.

When the IG 61 is turned on, the ECU 70 that has detected the ON signal of the IG 61 starts the process of FIG.
In step S101, the ECU 70 opens the shut-off valve 32 and the purge valve 36. In step S102, the ECU 70 opens the assist introduction valve 34 and the assist introduction valve 34. Note that the variable orifices 35 and 38 are preferably controlled to be fully opened in order to promptly perform hydrogen replacement.

  Then, hydrogen is supplied from the hydrogen tank 31 to the internal hydrogen supply manifold 11 from the front side to the rear side of the fuel cell stack 10 via the pipes 31a, 32a, 33a and the first hydrogen introduction port 11a (see FIG. 3). Further, since the assist introduction valve 34 is open, the hydrogen flowing through the pipe 32a is supplied from the rear side of the fuel cell stack 10 to the front through the pipes 34a and 35a and the second hydrogen introduction port 11b. It is supplied to the manifold 11. That is, hydrogen is supplied from both sides of the internal hydrogen supply manifold 11 extending in the stacking direction toward the center.

  The hydrogen flowing through the internal hydrogen supply manifold 11 in this way from both sides toward the center flows equally into the anode channel 26 of each single cell 20. As a result, the replacement of the anode flow path 26 with hydrogen proceeds, and the hydrogen concentration in the fuel cell stack 10 begins to rise substantially uniformly.

  At this time, since the purge valve 36 is open, the air in the anode flow path 26 is discharged to the outside through the internal hydrogen discharge manifold 12, the first hydrogen discharge port 12a, the pipe 36a, and the pipe 36b. Further, since the assist discharge valve 38 is also open, the air in the anode flow path 26 is discharged to the outside through the internal hydrogen discharge manifold 12, the second hydrogen discharge port 12b, the pipe 38a, the pipe 38b, and the pipe 39a. That is, the air in the anode channel 26 is discharged from both sides of the internal hydrogen discharge manifold 12 to the outside.

  Since the exhaust gas is discharged from both sides of the internal hydrogen discharge manifold 12 in this manner, the air in each anode flow path 26 can easily flow into the internal hydrogen discharge manifold 12 evenly. As a result, hydrogen replacement in each anode channel 26 proceeds substantially evenly, and the time required for hydrogen replacement can be shortened.

  In step S103, the ECU 70 is close to the assist introduction valve 34 and the assist discharge valve 38, and the hydrogen concentration C12 detected by the hydrogen sensor 19 disposed in the anode flow path 26 through which hydrogen is supplied and air is easily discharged is determined. Then, it is determined whether or not the reference hydrogen concentration is equal to or higher than C0. The reference hydrogen concentration C0 is a hydrogen concentration at which it is determined that the hydrogen replacement at the time of system startup is completed, is obtained by a preliminary test or the like, and is stored in the ECU 70 in advance.

  When it is determined that the hydrogen concentration C12 is equal to or higher than the reference hydrogen concentration C0 (S103 / Yes), the process of the ECU 70 proceeds to step S104. On the other hand, when it is determined that the hydrogen concentration C12 is not equal to or higher than the reference hydrogen concentration C0 (No in S103), the ECU 70 repeats the determination in step S103.

  In step S104, the ECU 70 closes the assist introduction valve 34 and the assist discharge valve 38.

  In step S105, the ECU 70 determines whether or not the hydrogen concentration C11 detected by the hydrogen sensor 18 disposed in the anode flow path 26 far from the assist introduction valve 34 and the assist discharge valve 38 is equal to or higher than the reference hydrogen concentration C0. .

  When it is determined that the hydrogen concentration C11 is equal to or higher than the reference hydrogen concentration C0 (S105 / Yes), the process of the ECU 70 proceeds to step S106. On the other hand, when it is determined that the hydrogen concentration C11 is not equal to or higher than the reference hydrogen concentration C0 (No in S105), the ECU 70 repeats the determination in step S105.

In step S106, the ECU 70 and the purge valve 36 are closed. Thereby, each anode channel 26 is replaced with hydrogen having a reference hydrogen concentration C0 or higher.
Thereafter, the ECU 70 proceeds to the end, and after confirming that the OCV of the fuel cell stack 10 is equal to or higher than a predetermined OCV, which is determined in advance, via a voltage sensor (not shown), the ECU 70 connects the fuel cell stack 10 and the external circuit. Connected to cause the fuel cell stack 10 to generate power in response to a power generation request.

≪Operation and effect of fuel cell system-When system is shut down≫
Next, with reference to FIG. 6, the operation | movement and effect at the time of the stop of the fuel cell system 1 are demonstrated. Note that when the IG 61 is turned off, the processing of FIG. 6 starts.

  In step S <b> 201, the ECU 70 closes the shutoff valve 32 and opens the purge valve 36 while operating the compressor 41.

In step S202, the ECU 70 opens the scavenging valve 51. Then, the scavenging gas (non-humidified air) from the compressor 41 is guided not only to the cathode flow path 28 but also to the anode system via the pipes 51a and 51b.
However, the timing for opening the scavenging valve 51 and the timing for starting scavenging are not particularly limited, and scavenging may be started continuously after the IG 61 is turned off. A configuration may be adopted in which scavenging is started when the outside air temperature detected via (not shown) decreases to a temperature (for example, 0 ° C.) at which scavenging is to be started.

In step S203, the ECU 70 opens the assist introduction valve 34 and the assist discharge valve 38. Then, the scavenging gas guided through the pipes 51 a and 51 b is supplied from both sides of the internal hydrogen supply manifold 11 and then supplied to the anode flow path 26 of each single cell 20. In parallel with this, hydrogen, water vapor and the like in each anode channel 26 are discharged from both sides of the internal hydrogen discharge manifold 12 to the outside.
In this way, scavenging gas is introduced from both sides in the stacking direction, and the gas in the anode channel 26 is discharged from both sides, so that scavenging of the anode channel 26 proceeds quickly. In order to advance the scavenging quickly, it is preferable to control the variable orifices 35 and 39 to be fully opened during the scavenging.

  In step S204, the ECU 70 determines whether or not the hydrogen concentration C12 detected through the hydrogen sensor 19 is equal to or less than a reference hydrogen concentration C1 at which residual hydrogen is suitably discharged and scavenging is completed. . The reference hydrogen concentration C1 is obtained by a preliminary test or the like and is stored in the ECU 70 in advance.

When it is determined that the hydrogen concentration C11 is equal to or less than the reference hydrogen concentration C1 (S204 / Yes), the process of the ECU 70 proceeds to step S205.
On the other hand, when it is determined that the hydrogen concentration C11 is not less than or equal to the reference hydrogen concentration C1 (S204, No), the processing of the ECU 70 repeats the determination of step S204.

  In step S205, the ECU 70 closes the assist introduction valve 34 and the assist discharge valve 38.

In step S206, the ECU 70 determines whether or not the hydrogen concentration C11 detected through the hydrogen sensor 18 is equal to or less than the reference hydrogen concentration C1.
When it is determined that the hydrogen concentration C11 is equal to or lower than the reference hydrogen concentration C1 (S206 / Yes), the process of the ECU 70 proceeds to step S207. On the other hand, when it is determined that the hydrogen concentration C11 is not equal to or less than the reference hydrogen concentration C1 (No in S206), the process of the ECU 70 repeats the determination in step S206.

In step S207, the ECU 70 closes the purge valve 36 and the scavenging valve 51 and stops the compressor 41.
Thereafter, the process of the ECU 70 proceeds to the end, and the control when the system is stopped is terminated.

≪Increase in power generation demand during normal power generation≫
Next, with reference to FIG. 7, a description will be given of a case where, for example, the accelerator pedal 62 is suddenly depressed and the power generation request for the fuel cell stack 10 suddenly increases during normal power generation (during normal travel).

  In step S301, the ECU 70 determines whether or not the depression change amount Δθ11 per unit time of the accelerator pedal 62 is equal to or larger than the reference depression change amount Δθ1. The reference depression change amount Δθ1 is a reference value for opening the assist introduction valve 34 and the assist discharge valve 38, and is obtained by a preliminary test or the like and stored in the ECU 70 in advance.

  When it is determined that the stepping change amount Δθ11 is greater than or equal to the reference stepping change amount Δθ1 (Yes in S301), the process of the ECU 70 proceeds to step S302. On the other hand, when it is determined that the stepping change amount Δθ11 is not equal to or larger than the reference stepping change amount Δθ1 (S301, No), the process of the ECU 70 proceeds to step S304.

  In step S302, the ECU 70 opens the assist introduction valve 34 and the assist discharge valve 38. Then, hydrogen is supplied from both sides of the internal hydrogen supply manifold 11, and the anode off gas is discharged from both sides of the internal hydrogen discharge manifold 12. Thereby, hydrogen is easily supplied to each anode flow path 26, and it is difficult for hydrogen shortage to occur in each single cell 20. Therefore, the power generated by the fuel cell stack 10 can be suddenly increased according to the amount of depression of the accelerator pedal 62.

In step S303, the ECU 70 increases the opening of the variable orifices 35 and 38 based on the depression change amount Δθ11, specifically, as the depression change amount Δθ11 increases. Thereby, the amount of hydrogen supplied to and discharged from each anode channel 26 can be made appropriate.
Thereafter, the processing of the ECU 70 returns to the start via a return.

In step S304, the ECU 70 closes the assist introduction valve 34 and the assist discharge valve 38.
Thereafter, the processing of the ECU 70 returns to the start via a return.

  As mentioned above, although preferred embodiment of this invention was described, this invention is not limited to the said embodiment, For example, it can change as follows in the range which does not deviate from the meaning of this invention.

In the above-described embodiment, the fuel cell system 1 that supplies hydrogen to the fuel cell stack 10 in two systems and discharges the anode off-gas from the fuel cell stack 10 in two systems is illustrated. However, the hydrogen supply side or anode off-gas discharge is illustrated. A fuel cell system in which only two sides are provided may be used.
Further, the present invention may be applied to a cathode system that supplies and discharges air. That is, a configuration may be adopted in which air is supplied to the fuel cell stack 10 in two systems and air (cathode offgas) is discharged from the fuel cell stack 10 in two systems.

  In the hydrogen replacement at the time of system startup according to the above-described embodiment, the assist introduction valve 34 and the assist discharge valve 38 are closed when the hydrogen concentrations C11 and C12 detected by the hydrogen sensors 18 and 19 respectively exceed the reference hydrogen concentration C0. In addition to this, for example, at least one of the assist introduction valve 34 and the assist discharge valve 38 may be closed.

In the above-described embodiment, the flow rate control means for controlling the flow rate of the gas flowing through the second fuel gas supply flow path configured to include the pipes 34a and 35b includes the normally closed assist introduction valve 34, the variable orifice 35, However, it may be configured by a butterfly valve, a needle valve, or the like.
The same applies to the flow rate control means for controlling the flow rate of the gas flowing through the second fuel gas discharge flow path constituted by including the pipes 38a, 38b, 39a.

  In the above-described embodiment, the case where the fuel cell system 1 is mounted on a fuel cell vehicle is illustrated. However, for example, the fuel cell system 1 may be incorporated in a fuel cell system mounted on a motorcycle, a train, or a ship. Moreover, a stationary fuel cell system for home use or a fuel cell system incorporated in a hot water supply system may be used.

It is a block diagram of the fuel cell system which concerns on this embodiment. It is a perspective view of the fuel cell stack concerning this embodiment. It is a disassembled perspective view of the fuel cell stack concerning this embodiment. It is a perspective view of the anode separator which concerns on this embodiment. It is a flowchart which shows the operation | movement at the time of system starting of the fuel cell system which concerns on this embodiment. It is a flowchart which shows the operation | movement at the time of the system stop of the fuel cell system which concerns on this embodiment. It is a flowchart which shows the operation | movement at the time of the electric power generation request increase of the fuel cell system which concerns on this embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Fuel cell system 10 Fuel cell stack 11 Internal hydrogen supply manifold (Internal fuel gas supply flow path)
11a 1st hydrogen inlet 11b 2nd hydrogen inlet 12 Internal hydrogen discharge manifold (internal fuel gas discharge flow path)
12a First hydrogen discharge port 12b Second hydrogen discharge port 13 Internal air supply manifold (internal oxidant gas supply flow path)
13a Air inlet 14 Internal air discharge manifold (Internal oxidant gas discharge flow path)
14a Air outlet 18, 19 Hydrogen sensor (concentration detection means)
20 single cell 21 MEA (membrane electrode assembly)
23 Anode 24 Cathode 25 Anode separator 26 Anode flow path (fuel gas flow path)
27 Cathode separator 28 Cathode flow path (oxidant gas flow path)
31 Hydrogen tank (fuel gas source)
31a, 32a, 33a Piping (first fuel gas supply channel)
34a, 34b, 35a Piping (second fuel gas supply channel)
33 Ejector 34 Assist introduction valve (flow control means)
35 Variable orifice (flow control means)
36a, 36b Piping (first fuel gas discharge flow path)
38a, 38b, 39a Piping (second fuel gas discharge flow path)
36c Piping (circulation flow path)
38 Assist discharge valve (flow control means)
39 Variable orifice (flow control means)
51 Scavenging valve 70 ECU
C0, C1 standard hydrogen concentration (predetermined fuel gas concentration)
C11, C12 Hydrogen concentration

Claims (5)

It is configured by laminating a plurality of single cells having fuel gas flow paths for supplying and discharging fuel gas to the anode of the membrane electrode assembly,
An internal fuel gas supply channel that distributes and supplies the fuel gas to the fuel gas channel of each unit cell, and the fuel gas is collectively discharged from the fuel gas channel of each unit cell in the stacking direction inside the unit cell. An internal fuel gas discharge channel,
The internal fuel gas supply channel has a first fuel gas inlet at one end and a second fuel gas inlet at the other end, and a fuel cell stack that opens to the outside,
A first fuel gas supply channel connecting a fuel gas source and the first fuel gas inlet;
A second fuel gas supply channel branched from the first fuel gas supply channel and connected to the second fuel gas inlet;
Flow rate control means for controlling the flow rate of the gas flowing through the second fuel gas supply flow path;
A fuel cell system comprising: An ejector disposed in the first fuel gas supply flow path;
A circulation flow path for returning the gas discharged from the internal fuel gas discharge flow path to the first fuel gas supply flow path via the ejector;
With
The fuel cell system according to claim 1, wherein an upstream end of the second fuel gas supply flow path is connected to the first fuel gas supply flow path upstream of the ejector. It is configured by laminating a plurality of single cells having fuel gas flow paths for supplying and discharging fuel gas to the anode of the membrane electrode assembly,
An internal fuel gas supply channel that distributes and supplies the fuel gas to the fuel gas channel of each unit cell, and the fuel gas is collectively discharged from the fuel gas channel of each unit cell in the stacking direction inside the unit cell. An internal fuel gas discharge channel,
The internal fuel gas discharge flow path has a first fuel gas discharge port on one end side and a second fuel gas discharge port on the other end side, and a fuel cell stack opened to the outside,
A first fuel gas discharge channel connected to the first fuel gas discharge port, through which fuel gas from the internal fuel gas discharge channel flows;
A second fuel gas is connected to the second fuel gas discharge port, connected to the first fuel gas discharge channel, and a second fuel gas from the internal fuel gas discharge channel is joined to the first fuel gas discharge channel. A fuel gas discharge channel;
Flow rate control means for controlling the flow rate of the gas flowing through the second fuel gas discharge channel;
A fuel cell system comprising: When the start of the fuel cell stack is instructed, when replacing each fuel gas flow path with fuel gas, the flow rate control means controls the gas to flow through the inside. The fuel cell system according to any one of claims 1 to 3. Concentration detection means for detecting the fuel gas concentration in the fuel cell stack,
The flow rate control means controls the flow rate of the gas passing through the inside so that the fuel gas concentration detected by the concentration detection means becomes a predetermined fuel gas concentration. The fuel cell system according to claim 1.

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