JP2009048790A - Fuel cell system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To facilitate a purge caused by a reactant while improving drainage performance by controlling a reactant circulation amount corresponding to an operating state of a fuel cell. <P>SOLUTION: In a fuel cell system, a fuel cell has a plurality of membrane-electrode assemblies and a plurality of separators. A reactant channel for circulating a reactant is formed in a face facing one electrode of each separator. An inlet and an outlet of the reactant channel are respectively connected with a supply manifold and an exhaust manifold. The supply manifold is arranged with an inlet opening/closing means for changing an opening/closing state of the inlet of the reactant channel. The exhaust manifold is arranged with an outlet opening/closing means for changing an opening/closing state of the outlet of the reactant channel. According to an operation mode of the fuel cell, the fuel cell system is controlled by switching between a first state, in which the outlet is opened when the inlet is closed while the outlet is closed when the inlet is opened, and a second state in which the inlet and the outlet are opened or closed together. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a fuel cell system. More specifically, the present invention relates to a fuel cell system including an electrolyte, a pair of electrodes disposed on both sides of the electrolyte, and a separator disposed to face the pair of electrodes.

  For example, JP 2003-59514 A discloses a stack type fuel cell in which a plurality of cells are stacked. In this conventional fuel cell, hydrogen, which is a fuel, is supplied to the anode electrode of each cell, and air, which is an oxidizing gas, is supplied to the cathode electrode. When hydrogen or oxygen is supplied to each electrode, an electrochemical reaction occurs by catalytic action, and electric energy is extracted. In this electrochemical reaction, water is generated at the cathode electrode.

  Here, the generated water generated by the electrochemical reaction of the fuel cell may block the air flow path of the cathode electrode, and may cause a smooth flow of air at the cathode electrode. If air is not smoothly supplied to the cathode electrode, stable power generation is not performed in the fuel cell, and there is a possibility that sufficient energy cannot be extracted. Therefore, in order to ensure stable power generation of the fuel cell, it is important to remove the generated water in the air flow path of the cathode electrode.

  For this reason, the above-described conventional fuel cell has an air supply / exhaust mechanism for increasing the air pressure in the air flow path in order to remove water in the air flow path. This air supply / exhaust mechanism has a structure in which a cylinder provided with a spiral groove is disposed in an air supply manifold (air supply pipe). A gap through which air can flow is opened between the cylindrical surface and the inner wall of the air supply pipe.

  During operation of the fuel cell, a certain amount of air is supplied from the gap portion to the air flow path of each cell. At this time, the groove on the surface of the cylinder rotates with the rotation of the cylinder. As a result, the cylindrical groove portion sequentially faces each air channel inlet of the cell. As described above, while the groove and the air flow path inlet face each other, a larger amount of air than the constant amount of air supplied from the gap is supplied into the air flow path. That is, air is supplied into the air flow path at a high air pressure. According to the above-described prior art, the water staying in the air channel can be discharged by temporarily increasing the air pressure supplied to the air channel in this way.

JP 2003-59514 A JP 09-31168 A JP 2004-342372 A

  In the above prior art, a cylinder having a groove is installed only on the upstream side of the air flow path, and the air flow is periodically increased by increasing the amount of air supplied to the air flow path by rotating the cylinder. ing. However, depending on the operating state of the fuel cell, the amount of water generated by the electrochemical reaction and the amount of water remaining in the air flow path are not always constant but are different. The amount of fuel and air (oxidant) required varies depending on the operating state of the fuel cell. Therefore, in order to prevent the shortage of fuel and air (oxidant) while effectively removing the generated water as needed, it is possible to perform control according to the operating condition of the fuel cell. Is desired.

  In the above prior art, the amount of air flowing in from the supply manifold is only increased by the amount flowing through the spiral groove. Therefore, the rise in pressure in the air flow path is small, and when the amount of generated water is large, the generated water that blocks the flow path may not be sufficiently removed.

  The present invention has been made to solve the above-described problems, and provides an improved fuel cell system that can effectively remove water in a flow path while suppressing shortage of fuel and oxidant. The purpose is to do.

In order to achieve the above object, a first invention is a fuel cell system,
A plurality of membrane-electrode assemblies comprising an electrolyte and a pair of electrodes respectively disposed on both sides of the electrolyte;
A plurality of reaction agent channels arranged so as to sandwich the membrane-electrode assembly and provided with a reactant flow channel for allowing the reactant to flow through each of the one electrode on the opposing surface facing the one electrode of the pair of electrodes. A separator;
A supply manifold that penetrates the plurality of separators in the stacking direction and is connected to an inlet of the reactant channel, and that feeds the reactant supplied to the one electrode into the reactant channel;
A discharge manifold that penetrates the plurality of separators in the stacking direction and is connected to an outlet of the reactant flow path, and distributes a waste discharged from the one electrode via the reactant flow path;
An inlet opening / closing means arranged in the supply manifold, for changing an opening / closing state of an inlet of the reactant channel;
An outlet opening / closing means that is disposed in the discharge manifold and changes an opening / closing state of an outlet of the reactant channel;
According to the operation mode of the fuel cell, controlling the inlet opening and closing means and the outlet opening and closing means,
When the inlet of the reactant channel is closed, the outlet of the reactant channel is opened, and when the inlet of the reactant channel is opened, the outlet of the reactant channel is closed. A first state,
A second state in which both the inlet of the reactant channel and the outlet of the reactant channel are open or closed;
Control means for switching and controlling;
It is characterized by providing.

According to a second aspect of the present invention, in the first aspect of the present invention, the fuel cell further includes an activation mode determination unit that determines whether or not the operation mode of the fuel cell is an activation mode for activating the stopped fuel cell.
The control means controls to be in the second state when it is determined that the activation mode is set.

A third invention further comprises stop mode determination means for determining whether or not the operation mode of the fuel cell is a stop mode when stopping the fuel cell in the operation state in the first or second invention,
The control means controls to be in the first state when it is determined that the stop mode is set.

According to a fourth aspect of the present invention, in any one of the first to third aspects, the apparatus further comprises flooding detection means for detecting occurrence of flooding during operation of the fuel cell,
When the flooding is detected, the control means includes a timing at which an inlet of the reactant channel is opened, a timing at which an outlet of the reactant channel is closed or opened, and the reactant. The inlet opening / closing means and the outlet opening / closing are set such that the timing at which the inlet of the flow path is closed and the timing at which the outlet of the reactant flow path is closed or opened are shifted from each other. The means is controlled.

According to a fifth invention, in any one of the first to fourth inventions, during normal operation of the fuel cell,
A power generation amount detecting means for detecting a power generation amount of the fuel cell;
An opening / closing speed setting means for setting a speed for changing the opening / closing state of the inlet of the reactant channel and a speed for changing the opening / closing state of the outlet of the reactant channel according to the power generation amount;
In addition,
The control means controls the opening and closing states of the inlet of the reactant channel and the outlet of the reactant channel to change according to a set speed.

A sixth invention is any one of the first to fifth inventions,
The inlet opening and closing means is a rotating body rotatably installed in the supply manifold,
The control means controls the opening / closing state of the inlet of the reactant flow path by changing the opening area of the inlet of the reactant flow path by controlling the rotation of the rotating body.

In a seventh aspect based on the sixth aspect, the inlet opening / closing means is
A rotating shaft rotatably installed in the supply manifold;
The opening area of the inlet of the reactant flow path is changed by changing the contact area with the inlet of the reactant flow path by being spirally arranged around the rotation axis and rotating with the rotation of the rotary shaft. A spiral member to be changed;
It is characterized by providing.

In an eighth aspect based on the sixth aspect, the inlet opening / closing means comprises:
A rotating shaft rotatably installed in the supply manifold;
A rotating member that is arranged around the rotating shaft and changes the opening area of the inlet of the reactant flow path by rotating with the rotation of the rotating shaft to change the contact area with the inlet of the reactant flow path. When,
It is characterized by providing.

According to a ninth invention, in any one of the first to eighth inventions,
The outlet opening / closing means is a rotating body rotatably installed in the discharge manifold,
The control means controls the opening / closing state of the outlet of the reactant flow path by changing the opening area of the outlet of the reactant flow path by controlling the rotation of the rotating body.

In a tenth aspect based on the ninth aspect, the outlet opening / closing means is
A rotating shaft rotatably mounted on the discharge manifold;
The opening area of the outlet of the reactant channel is changed by changing the contact area with the outlet of the reactant channel by rotating with the rotation of the rotating shaft and changing the contact area with the outlet of the reactant channel. A spiral member,
It is characterized by providing.

In an eleventh aspect based on the ninth aspect, the outlet opening / closing means is
A rotating shaft rotatably mounted on the discharge manifold;
A rotating member that is arranged around the rotating shaft and changes the opening area of the outlet of the reactant flow path by rotating with the rotation of the rotating shaft to change the contact area with the outlet of the reactant flow path. When,
It is characterized by providing.

In a twelfth aspect of the invention based on any one of the first to eleventh aspects of the invention,
The inlet opening / closing means is a rotating body rotatably installed in the supply manifold,
The outlet opening / closing means is a rotating body configured in the same shape as the inlet opening / closing means, and is rotatably installed in the discharge manifold,
The control means controls the first state by setting the rotation of the inlet opening / closing means and the outlet opening / closing means to the same phase, and the rotation of the inlet opening / closing means and the outlet opening / closing means is shifted by 180 degrees. It is characterized by controlling to the said 2nd state by setting it as a reverse phase.

  In a thirteenth aspect based on any one of the first to twelfth aspects, the one electrode is a cathode electrode.

  According to the first invention, the fuel cell system includes an inlet opening / closing means for changing an opening / closing state of the inlet of the reactant channel to each of the electrodes, and an outlet opening / closing for changing the opening / closing state of the outlet of the reactant channel. Means. Further, the open / closed state of the inlet of the reactant channel and the open / closed state of the outlet are, depending on the operation mode of the fuel cell, the first state where the outlet is closed when the inlet is open, Control is performed by switching to a second state in which both are opened or closed. Accordingly, the flow rate of the reactant to one electrode and the pressure in the flow path can be changed according to the operating state of the fuel cell.

  According to the second invention, when the operation mode of the fuel cell is the startup mode, the outlet is controlled to be open when the inlet is open, and the outlet is also closed when the inlet is closed. The In this state, since the reactant flows when both the inlet and the outlet are open, the reactant can be smoothly circulated, and the reactant flow path can be replaced earlier at startup. it can. In particular, here, in a state where both the inlet and outlet of a certain reactant channel are closed, it is possible to make both the inlet and outlet of another reactant channel open. For this reason, even when the flow rate of the reactant is the same, the reactant can be concentrated and supplied to the reactant flow path having an open inlet and outlet, and the flow rate of the reactant flowing through the reactant flow path can be increased. As a result, the variation between the reactant channels can be reduced, and the gas remaining in the reactant channel can be surely replaced.

  According to the third aspect of the invention, when the operation mode of the fuel cell is the stop mode, the outlet is closed when the inlet is open, and the outlet is opened when the inlet is closed. . Here, when the inlet is open and the outlet is closed, the reactant is sucked from the inlet side, and when the inlet is closed and the outlet is open, the exhaust is discharged from the outlet side. Accordingly, it is possible to increase the pressure change in the reactant flow path, and it is possible to efficiently remove the generated water that stays rapidly when the fuel cell is stopped even at the same flow rate of the reactant.

  According to the fourth invention, when flooding is detected during operation of the fuel cell, the timing at which the inlet of the reactant channel is opened or closed and the timing at which the outlet is opened or closed are , Both are controlled so as not to match. Therefore, when flooding occurs, it is possible to increase the pressure fluctuation of the reactant flow path while ensuring the supply of the reactant, and it is possible to quickly remove the water in the stay during flooding.

  According to the fifth invention, during the normal operation of the fuel cell, the speed for changing the opening / closing state of the inlet of the reactant flow path and the speed for changing the opening / closing state of the outlet are determined according to the amount of power generation. Thereby, according to the electric power generation amount, it can set so that sufficient reactant can be supplied without shortage.

  According to any one of the sixth to twelfth inventions, the inlet opening / closing means or the outlet opening / closing means is a rotating body rotatably installed in the manifold, and the control means controls the rotation of the rotating body. Thus, the opening area of the inlet or the outlet is changed. Thereby, the open / closed state of the flow path of each electrode can be changed at the same time with only one component, and removal of generated water and replacement with a reactant can be ensured with a simpler system.

  According to the thirteenth aspect, the inlet opening / closing means and the outlet opening / closing means are installed on the cathode electrode side. Thereby, in the fuel cell in which water is generated at the cathode electrode, the occurrence of flooding can be more effectively prevented.

  Embodiments of the present invention will be described below with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals, and the description thereof is simplified or omitted.

Embodiment 1 FIG.
[System configuration of the embodiment]
FIG. 1 is a schematic diagram for explaining the overall configuration of a fuel cell system according to Embodiment 1 of the present invention. The system shown in FIG. 1 has a fuel cell 10. End plates 12 are disposed on both sides of the fuel cell 10. A plurality of cells 14 are stacked inside the fuel cell 10 sandwiched between the end plates 12. Each of the cells 14 has an electrolyte membrane (electrolyte) and a membrane-electrode assembly (MEA) composed of a cathode electrode and an anode electrode, which are a pair of electrodes disposed on both sides thereof. In addition, separators are disposed on both sides of the MEA. As will be described later, an air flow path (reactant flow path) for circulating air is formed on the surface of the separator that is in contact with the cathode electrode. A fuel flow path for supplying hydrogen as fuel is formed on the surface of the separator in contact with the anode electrode.

  The fuel cell 10 is formed with an air supply manifold 18 and an air discharge manifold 20 for supplying and exhausting air in the air flow path through the separator of each cell 14. A supply screw rotor 30 (inlet opening / closing means), which will be described later, is disposed in the air supply manifold 18. A discharge screw rotor 32 (exit opening / closing means), which will be described later, is disposed in the air discharge manifold 20. Motors 34 and 36 for controlling the rotation of the supply screw rotor 30 and the discharge screw rotor 32 are attached to the supply screw rotor 30 and the discharge screw rotor 32, respectively. Although not shown in the drawing, the motors 34 and 36 are attached with instruments that generate outputs corresponding to the rotational speed and phase of the screw rotors 30 and 32.

  The air supply manifold 18 of the fuel cell 10 is connected to an air supply pipe 40 outside the fuel cell 10 at an air inlet (not shown). On the other hand, the air discharge manifold 20 is connected to an air discharge pipe 42 outside the fuel cell 10 at an air discharge port (not shown). The air supply pipe 40 is provided with an inlet pressure sensor 44 for generating an output corresponding to the internal pressure thereof, and the air discharge pipe 42 is provided with an outlet pressure sensor 46 for generating an output corresponding to the internal pressure thereof. Yes. By detecting the outputs of the inlet pressure sensor 44 and the outlet pressure sensor 46, the inlet pressure and the outlet pressure of the fuel cell 10 can be detected. Further, the fuel cell 10 is provided with an ammeter 48 that generates an output corresponding to a current to be generated.

  Although not shown, the fuel cell 10 is formed with a fuel supply manifold and a fuel discharge manifold for supplying and exhausting hydrogen in the fuel flow path of each cell 14 through the separator of each cell 14. Yes. The fuel supply manifold is connected to a fuel supply source via a fuel supply pipe outside the fuel cell 10. That is, hydrogen as fuel supplied from the fuel supply source is supplied to the fuel flow path of each cell 14 via the fuel supply pipe and the fuel supply manifold.

  The fuel cell system shown in FIG. The control device 50 is connected to instruments attached to the motors 34 and 36, an inlet pressure sensor 44, an outlet pressure sensor 46, and an ammeter 48, and receives the output signals from these instruments and the like to operate the fuel cell 10. Detect information about the state. The control device 50 is connected to each member necessary for the operation of the fuel cell 10 and controls the operation of the fuel cell 10. For example, the control device 50 is connected to the motors 34 and 36 of the screw rotors 30 and 32, and controls the rotation and the like of the screw rotors 30 and 32 by issuing control signals thereto.

  FIG. 2 is a schematic diagram for explaining the screw rotor of the fuel cell system according to Embodiment 1 of the present invention. In FIG. 2, only the air flow path 16 of each cell 14 is schematically enlarged for simplification of explanation. The air flow path 16 is connected to the air supply manifold 18 and the air discharge manifold 20 of the fuel cell 10 at both ends thereof. As a result, air flows from the air supply manifold 18 into the air flow path 16, and the air off-gas (exhaust agent) is discharged to the air discharge manifold 20.

  The screw rotor 30 installed in the air supply manifold 18 has a rotating shaft 60 connected to the motor 34. A screw portion 62 (spiral member) formed in a screw shape is attached around the rotary shaft 60. The rotation shaft 60 is rotated in conjunction with the rotation of the motor 34 by controlling the number of rotations, the rotation start position, and the like by a control signal from the control device 50. The screw part 62 rotates in conjunction with the rotation of the rotating shaft 60.

  The screw portion 62 is at least an inner wall (hereinafter referred to as “inlet surface”) including a connection portion (inlet) with the air flow path 16 in the air supply manifold 18, that is, in the cross section of FIG. When the underline of the manifold 18 is at a position opposite to the surface indicated, the manifold 18 is disposed so as to be in contact with the flow path inlet. Further, the width W of the screw part 62 in the direction of the rotation axis 60 is the same as the interval D between adjacent screw parts 62 in the cross section in the direction of the rotation axis 60.

  Here, the screw portion 62 is located at a position facing the inlet surface, and when the screw portion 62 faces the inlet of the air flow path 16 of the cell 14 at that position, the inlet of the portion is closed. Further, when the screw part 62 rotates with the rotation of the rotating shaft 60, the contact surface between the inlet and the screw part 62 gradually shifts, and the opening area of the inlet gradually changes. Specifically, when the rotation shaft 60 rotates in the rotation direction shown in FIG. 2, the contact surface between the screw portion 62 and the entrance apparently shifts to the right in the drawing. As described above, the contact surface with the screw portion 62 is moved by the rotation of the rotating shaft 60, so that the opening area of the inlet of the air flow passage 16 gradually increases from the closed state and moves to a position where the screw portion 62 does not contact. Then, the opening state is completely opened, the opening area gradually decreases from the opening state, and the screw portion 62 is completely in contact with each other to be closed again.

  On the other hand, the discharge screw rotor 32 installed in the air discharge manifold 20 is the same as the supply screw rotor 30. Specifically, the discharge screw rotor 32 has a rotating shaft 64 connected to the motor 36. A screw portion 66 (spiral member) formed in the shape of a screw is attached around the rotation shaft 64. The rotation shaft 64 is rotated in conjunction with the rotation of the motor 36 by controlling the rotation speed, the rotation start position, and the like by a control signal from the control device 50. The screw portion 66 rotates in conjunction with the rotation of the rotating shaft 64.

  The screw portion 66 is an inner wall (hereinafter referred to as “discharge port surface”) of a portion including at least a connection portion (exit) with the air flow path 16 of the air discharge manifold 20, that is, in the cross section of FIG. When it is at a position opposite to the surface indicated by the upper line, it is arranged so as to contact this discharge port surface. Further, the width W of the screw portion 66 in the direction of the rotation axis 64 and the distance D between adjacent screw portions 66 in the cross section in the direction of the rotation shaft 64 are the same.

  The screw part 66 is located at a position facing the discharge port surface, and closes the outlet of the part when facing the outlet of the air flow path 16 of the cell 14 at that position. Moreover, when the screw part 66 rotates with rotation of the rotating shaft 64, the contact surface of an exit and the screw part 66 will shift | deviate gradually, and the opening area of an exit will change gradually. Specifically, when the rotation shaft 64 rotates in the rotation direction shown in FIG. 2, the contact surface between the screw portion 66 and the outlet apparently shifts to the right in the drawing. Thus, the rotation surface of the rotating shaft 64 moves the contact surface with the screw portion 66, so that the outlet of the air flow path 16 gradually increases its opening area from the closed state and moves to a position where the screw portion 66 does not contact. Then, it will be in a completely open state, the opening area will gradually decrease from the open state, and it will be in a closed state again when it moves to a position where the screw part 66 is completely in contact.

  3 and 4 are schematic diagrams for explaining the opening / closing timing of the air flow path 16 due to the rotation of the supply screw rotor 30 and the discharge screw rotor 32 and the pressure change at that time in Embodiment 1 of the present invention. is there. 3A and 4A schematically show changes in the positions of the screw portions 62 and 66 that are in contact with one cell 14 in a circular graph, and only the air channel 16 that is in contact therewith is shown. FIG. 3B and FIG. 4B show pressure changes in that state.

  In the example of FIG. 3, the rotation of the supply screw rotor 30 and the discharge screw rotor 32 starts from the same angle (same position) and is rotated at the same rotation number, that is, the positions of the screw parts 62 and 66 are the same. The case where the rotating shafts 60 and 64 are rotated so as to have the same phase is shown. In this example, the air channel 16 is fully open while the inlet is fully closed, and fully closed while the inlet is fully open (first state). ).

  On the other hand, in the example of FIG. 4, when the rotation of the supply screw rotor 30 and the discharge screw rotor 32 starts from the start position shifted by 180 degrees and is rotated at the same rotation number, that is, the positions of the screw parts 62 and 66 are The case where the rotating shafts 60 and 64 are rotated so as to have an opposite phase shifted by 180 degrees is shown. In this example, the air flow path 16 is completely closed at the timing when the inlet is completely closed, and the outlet is also fully opened at the timing when the inlet is fully opened (second state).

  Specifically, in the state [1] of the cell 14 shown in FIG. 3A, about half of the inlet / outlet of the air flow path 16 is in contact with the screw portions 62 and 66 and is about half open. It has become. In this state, the atmosphere flows into the air flow path 16 due to the inlet pressure difference ΔP, and the pressure in the cell 14 becomes relatively high as shown in FIG.

  When the screw portions 62 and 66 are moved by the rotation of the rotary shafts 60 and 64 from the state [1] and become the states [2] to [4], the inlet is closed and the outlet is opened. . Normally, during operation of the fuel cell 10, the pressure (outlet pressure) on the air discharge manifold 20 side is low, and therefore, when the inlet side is closed and the outlet is opened, air off gas is discharged from the air flow path 16. As the air flow advances, the air passage 16 is gradually in a state of a low outlet pressure.

  After that, when the state of [5] is reached and both the inlet and the outlet are opened, the pressure in the air flow path 16 rises at once, and air is introduced into the air flow path 16 with a strong force. . The water staying in the air flow path 16 can be drained by the momentum of air inflow due to this pressure fluctuation.

  Further, when the screw portions 62 and 66 are rotated and the inlets of the air flow path 16 are completely opened and the outlets are closed as in the states [6] to [8], the air flows from the air flow path 16 to the air. Is no longer discharged, and as shown in FIG. 3B, the pressure in the air flow path 16 rises to a high state. Thereafter, the state [1] is entered again.

  In the stop mode in which the operation of the fuel cell 10 is stopped, it is desirable to sufficiently drain the air flow path 16 in preparation for the next start-up or the like. Therefore, the inlet pressure is increased to increase the inlet / outlet pressure difference ΔP. In this state, the positional relationship between the screw portions 62 and 66 is the same phase relationship shown in FIG. Thus, in a certain air flow path 16, when the inlet is open and the outlet is closed, air is sucked from the inlet side, and when the inlet is closed and the outlet is open, air and stagnation from the outlet side. Water is discharged. Therefore, the pressure change in the air flow path 16 can be increased, and the generated water staying quickly in the fuel cell stop mode can be efficiently drained even with the same air flow rate. That is, here, in a state where the inlet / outlet pressure difference ΔP is increased, the air inflow state and the closed state of the air passage 16 are repeated in a short period of time, thereby increasing the pressure fluctuation in the air passage 16 and draining. Can be improved.

  In the stop mode, the rotation speed Re is set to a rotation speed changed according to the flow path length L. It is considered that a resonance state of pressure occurs in this, pressure fluctuation can be further increased, and drainage can be improved. Accordingly, the rotation speed Re here is rotation speed Re = ke × sonic velocity C / flow path length L. Note that “ke” is a coefficient and can be determined in advance by experiments or the like.

  On the other hand, as shown in FIG. 4, when the screw portions 62 and 66 are in the opposite phase, the opening and closing timings of the inlet and the outlet are the same. That is, in a certain air flow path 16, the outlet is also opened when the inlet is opened, and the outlet is also closed when the inlet is closed. Specifically, the state where both the inlet and the outlet are opened as in the state [1] in FIG. 4 is changed to the state where both the inlet and the outlet are closed as in the states [2] to [3]. ], The inlet and outlet are both opened as in the state, and the state returns to the state [1]. In this way, by opening and closing the inlet and outlet at the same timing, the air inflow state and the state where no air flows into the air flow path 16 are repeated.

  In the start mode when starting the fuel cell 10 from the stop state, the control is performed in the reverse phase of FIG. As a result, air flows when both the inlet and outlet of an air flow path 16 are in an open state, so that air can flow smoothly in the air flow path 16. Furthermore, when both the inlet and outlet of an air channel 16 are open, there is another air channel in which both the inlet and outlet are closed. For this reason, even if the flow rate of air is the same, air can be intensively supplied to the air channel 16 where the inlet and outlet are open, and the flow rate of the air flowing through the air channel 16 can be increased. Therefore, the variation between cells can be reduced, and the gas remaining in the air flow path can be surely replaced in the startup mode. As described above, the phase is reversed in the start-up mode, so that gas replacement in the air flow path 16 is sufficiently performed and stable power generation can be performed in an earlier state.

  In the start-up mode, the screw rotors 30 and 32 are rotated relatively slowly in order to reliably perform gas replacement of individual cells. Specifically, the rotational speed Rs of the rotary shafts 60 and 64 is set to Rs = ks × gas scavenging flow rate / flow path volume V so that the gas corresponding to the flow path volume is replaced. Here, “ks” is a coefficient and can be determined in advance by experiments or the like.

  Further, during normal operation of the fuel cell 10, for example, when the generated water increases and it is desired to discharge it, it is changed to the same phase side, and when it is desired to keep the generated water, it is changed to the opposite phase side. Control.

  In this state, the rotating shafts 60 and 62 are rotated at a high speed that is proportional to the discharge current so as not to cause fuel shortage and oxygen shortage. By rotating the rotary shafts 60 and 64 in this way to increase the opening and closing speeds of the inlet and outlet of the air flow path 16, a large amount of air is introduced when the power generation amount increases. For this reason, in the first embodiment, the rotational speed R during normal operation of the fuel cell 10 is obtained by the rotational speed R = k × discharge current I. Here, “k” is a coefficient and can be determined in advance by experiments or the like.

  Further, when the load is high, the rotational speed R is further increased by changing the coefficient “k” to be larger. As a result, when the output is high, more air can be introduced by causing pressure fluctuations at a higher speed, and it is possible to efficiently remove the generated water and introduce the air. Further, if the rotation direction of the screw rotors 30 and 32 is taken into consideration, the air can be transported to the deeper cell by increasing the rotation speed R. In other words, the screw rotors 30 and 32 can function as assist pumps, and the flow rate can be increased in a state where oxygen deficiency tends to occur.

  As described above, in the first embodiment, the screw rotors 30 and 32 are controlled in the opposite phase in the startup mode of the fuel cell 10 and switched to the same phase when the stop mode is entered. Thereby, the air flow rate and pressure fluctuation according to the operation state can be caused, drainage can be improved, and the power generation performance of the fuel cell can be improved.

  FIG. 5 is a flowchart for illustrating a control routine executed by the control device in the first embodiment of the present invention. The routine of FIG. 5 is a routine that is repeatedly executed at regular intervals during the operation of the fuel cell 10.

  In the routine of FIG. 5, it is first determined whether or not the fuel cell 10 is being operated (S100). If the operation of the fuel cell 10 is not recognized in step S100, the control of the screw rotors 30 and 32 is also unnecessary, so this routine is temporarily terminated.

  On the other hand, if it is determined in step S100 that the fuel cell 10 is operating, a pressure difference ΔP between the inlet pressure and the outlet pressure of the fuel cell 10 is obtained (S102). Here, the outputs of the inlet pressure sensor 44 and the outlet pressure sensor 46 are read by the control device 50, the inlet pressure and the outlet pressure are obtained from these outputs, and the pressure difference ΔP is obtained by calculating the difference between the two.

  Next, it is determined whether or not the current operation mode of the fuel cell 10 is the start mode when starting from the stop state of the fuel cell 10 (S104). If it is determined in step S104 that the start mode is set, the supply screw rotor 30 and the discharge screw rotor 32 are controlled to the start mode.

  Specifically, first, the supply screw rotor 30 and the discharge screw rotor 32 are set to rotate in opposite phases (S106). That is, as shown in FIG. 3, the rotation start angles of the rotary shafts 60 and 64 are controlled to be shifted by 180 degrees.

  Next, the rotational speed Rs of the rotating shafts 60 and 64 of both screw rotors 30 and 32 is calculated (S108). The rotation speed Rs in the start mode is obtained according to an arithmetic expression for the rotation speed Rs stored in the control device 50 in advance. Specifically, the rotational speed Rs of the start-up mode is obtained according to the rotational speed Rs = ks × gas scavenging amount / air channel volume V.

  Next, the rotation of the rotation shafts 60 and 64 is controlled according to the starting rotation speed Rs (S110). Here, a control signal is sent from the control device 50 so as to have a rotational speed and an opposite phase, and the rotation by the motors 34 and 36 is controlled. As a result, necessary air corresponding to the volume V of the air flow path 16 can be introduced into the air flow path 16 and the purge at the time of activation can be performed quickly.

  On the other hand, when it is not recognized in step S104 that the operation mode of the fuel cell 10 is the start mode, it is next determined whether or not the operation state of the fuel cell 10 is the stop mode (S112). If the stop mode is recognized in step S112, the supply screw rotor 30 and the discharge screw rotor 32 are controlled to the stop mode. That is, first, as shown in FIG. 4, the supply screw rotor 30 and the discharge screw rotor 32 are set to have the same phase (S114). That is, the rotation start angles of the rotary shafts 60 and 64 are set to be the same. Thus, when the rotation of both screw rotors 30 and 32 is started, the state where the inlet of the air flow path 16 is opened and the outlet is closed, or the state where the inlet is closed and the outlet is opened is repeated.

  Next, control is performed so that the inlet / outlet pressure difference ΔP is increased (S116). Specifically, the inlet pressure is controlled to increase. The inlet pressure here is determined in advance by experiments or the like and stored in the control device 50 as a pressure that allows sufficient drainage.

  Next, the rotational speed Re in the stop mode is calculated (S118). The rotation speed Re in the stop mode is set so as to correspond to the flow path length L. Specifically, the calculation is performed according to an arithmetic expression stored in advance in the control device. Here, the calculation is performed using an arithmetic expression of the rotational speed Re = ke × the speed of sound C / the channel length L.

  Thereafter, the rotation of both screw rotors 30 and 32 is controlled by controlling the set phase and rotation speed Re (S110). Specifically, a control signal is issued from the control device 50, and the motors 34 and 36 attached to the rotary shafts 60 and 64 are thereby controlled, so that the screw parts 62 and 66 have the same phase and the rotational speed Re. It will rotate.

  On the other hand, when it is not recognized in step S112 that the fuel cell 10 is in the stop mode, it is determined that the operation mode of the fuel cell 10 is the normal operation mode. In this case, first, the current of the fuel cell 10 is detected (S120). The current is detected according to the output of the ammeter 48 attached to the fuel cell 10 by the control device 50.

  Next, the screw rotors 30 and 32 are controlled to the normal operation mode. That is, first, the rotational speed R of both the screw rotors 30 and 32 is calculated (S122). The rotational speed R in the normal operation mode is calculated according to an arithmetic expression stored in the control device 50 in advance. Specifically, here, in order to prevent shortage of air supplied to the air passage 16 and flooding, the rotation speed R = k × discharge current I is obtained in proportion to the current current I detected in step S118.

  Next, the phases of the screw rotors 30 and 32 are calculated (S124). Here, depending on the operating state of the fuel cell 10, the current screw rotor 30 is changed so as to change to the same phase side when removing the generated water and to the opposite phase side when holding the generated water. A correction amount for 32 phases is obtained and the phase is determined.

  Thereafter, the rotational speeds and phases of the rotary shafts 60 and 64 by the motors 34 and 36 are set to the rotational speed R and phase obtained in steps S122 and S124, and the screw rotors 30 and 32 are controlled (S110).

  As described above, in the first embodiment, the air flow in the air flow path 16 can be controlled by the rotation of the screw rotors 30 and 32. As a result, pressure fluctuation can be caused in the air flow path 16 and the amount of air flow can be increased or decreased. Therefore, the generated water accumulated in the air passage 16 can be discharged as needed, and the air passage 16 can be quickly purged.

  In the first embodiment, the case where the screw rotors 30 and 32 are in the opposite phase in the start mode and the same phase in the stop mode has been described. However, the present invention is not limited to this. For example, the phase may be shifted to some extent in the stop mode without being fixed only to the same phase and the opposite phase. Even by shifting the phase in this way, the amount of pressure fluctuation in the air channel 16 can be changed to some extent, so that the generated water staying in the air channel can be effectively discharged as necessary. . The same applies to the second embodiment.

  Further, the control of the screw rotors 30 and 32 in the normal operation mode according to the present invention is not limited to that described in the first embodiment. For example, it is considered that by increasing the phase difference between the screw rotors 30 and 32, the opening and closing timings of the inlet and outlet can be shifted and the pressure fluctuation can be increased. Therefore, it is also effective to control the screw rotors 30 and 32 so that the phase difference becomes large, for example, when it is detected that flooding has occurred. In addition, since the phase difference in such a case differs depending on the width of the air flow path, the interval between the screw portions 62 and 66, etc., the phase difference may be set to increase the pressure fluctuation in consideration of these. The flooding can be detected by monitoring the cell voltage of each cell 14. The same applies to the second embodiment.

  In the first embodiment, the calculation formulas for the respective rotational speeds R, Rs, and Re have been described. However, the rotational speed is not limited to this in the present invention. The number of rotations in each mode may be any as long as it can effectively perform purging, removal of generated water, and the like necessary in that mode. Further, the rotational speed is not limited to the one that changes according to each operation mode, and it may be always a constant rotational speed. The same applies to the second embodiment.

  In the first embodiment, the case where the opening areas of the air flow paths 16 of one cell 14 are controlled by the screw portions 62 and 66 has been described. However, the present invention is not limited to this. For example, for each of a plurality of cell groups, screw portions 62 and 66 are provided with a width that opens and closes the air flow path 16, and the air flow paths 16 of each of the plurality of cell groups are provided. It is also possible to control opening and closing. In this case, the control of the first embodiment is applied so that the opening and closing timings of the inlet and outlet of the air flow path 16 are the same phase and opposite phases for each cell group. be able to. The same applies to the second embodiment.

  Moreover, the screw rotors 30 and 32 having the same shape are used on the inlet side and the outlet side, and the case where the width W of the screw parts 62 and 66 of each screw rotor and the distance D between the screw parts are the same has been described. By making the screw rotors 30 and 32 have the same shape as described above, it is possible to easily realize the control of the same phase and the opposite phase only by controlling the start angle. However, in the present invention, the opening / closing means is not limited to this, and screw rotors having different shapes on the inlet side and the outlet side may be used. In this case, each screw rotor may be controlled separately so that the in-phase and anti-phase states of FIGS. 3 and 4 are realized.

  Moreover, in Embodiment 1, the case where the screw rotors 30 and 32 were provided only in the air flow path 16 side was demonstrated. However, the present invention is not limited to this, and a similar screw rotor can be provided on the fuel flow path side. For example, by installing a screw rotor on the fuel flow path side and performing control similar to the above-described start mode, the inside of the fuel flow path can be purged with fuel earlier at start-up. The same applies to the second embodiment.

  Further, the first embodiment has been described assuming a solid polymer fuel cell. However, the present invention is not limited to this, and can be applied to other fuel cells as long as it has a stack structure in which a plurality of membrane-electrode assemblies are separated by separators.

  In the control routine of FIG. 5, for example, step S106, S110, or S114 is executed to implement the “control unit” of the present invention, and step S104 is executed to execute “activation mode determination unit”. ”Is realized, and“ stop mode determining means ”is realized by executing step S112,“ power generation amount detecting means ”is realized by executing step S120, and“ "Opening and closing speed setting means" is realized.

Embodiment 2. FIG.
The system configuration of the fuel cell of the second embodiment is the same as that of the first embodiment except that the shapes of the rotors that are the inlet opening / closing means and the outlet opening / closing means are different. 6 and 7 are schematic views for explaining the configuration of the inlet opening / closing means and the outlet opening / closing means of the second embodiment.

  As shown in FIG. 6, in the supply rotor 70 and the discharge rotor 80 of the second embodiment, a plurality of semi-discs 74 and 84 are attached to the rotating shafts 72 and 82 in place of the screw portions 62 and 66, respectively. Configured. The semicircular plates 74 and 84 have the same thickness as the total length in the stacking direction of the plurality of cell groups. Further, when the semicircular plate 74 is located at a position facing the inflow port surface, the semicircular plate 74 is configured to contact and close the inlet. Similarly, the semicircular plate 84 is configured to contact the outlet and close the outlet when the semicircular plate 84 is at a position facing the discharge port surfaces of the plurality of cell groups.

  The adjacent semi-discs 74 and 84 are attached to the rotary shafts 72 and 82 so as to be shifted from each other by a predetermined angle around the rotary shafts 72 and 82. Therefore, when the rotating shafts 72 and 82 are rotated, the opening degree of the inlet and the outlet is slightly different for each adjacent cell group as shown in FIG.

  Here, the supply rotor 70 and the discharge rotor 80 are configured in the same shape. In other words, the semicircular plates 74 and 84 are arranged with the same interval and the same angular deviation between the supply rotor 70 and the discharge rotor 80. Accordingly, the rotary shafts 72 and 82 are set to move in the same phase when the rotation starts from the same rotation angle. That is, in a certain cell group, the inlet is in an open state and the outlet is in a closed state. On the other hand, in other cell groups, the inlet is closed and the outlet is opened. Therefore, the in-phase state as described in FIG. 3 is realized.

  On the other hand, when the rotation start angle is shifted by 180 degrees and rotation is started, both the inlet and the outlet are opened in a certain cell group, and both the inlet and the outlet are closed in a certain cell group. Thereby, the reverse phase state of FIG. 4 is realized as in the first embodiment. Note that the control of the rotors 70 and 80 of the second embodiment is executed by the same routine as that of FIG.

  The inlet opening / closing means and the outlet opening / closing means are not limited to the configurations described in the first and second embodiments. In the present invention, the inlet opening / closing means and the outlet opening / closing means are not limited as long as they can open and close the air flow path 16 and can control the opening and closing states of the inlet and outlet differently from other cells or groups of cells. It is good also as a shape. For example, the same control is performed by arranging lid-like members that contact the inlet or outlet and can completely close them at every cell interval and gradually shift them in the lateral direction (that is, the cell stacking direction). be able to.

  Moreover, the case where the same shape opening / closing means is used on the inlet side and the outlet side has been described. By using the same shape as described above, it is possible to easily realize the control of the same phase and the opposite phase only by adjusting the start angle. However, the opening / closing means is not limited to this in the present invention, and opening / closing means having different shapes on the inlet side and the outlet side may be used.

  Further, in the above embodiment, when the number of each element, number, quantity, range, etc. is mentioned, it is mentioned unless otherwise specified or clearly specified in principle. The number is not limited. Further, the structures described in the embodiments, steps in the method, and the like are not necessarily essential to the present invention unless otherwise specified or clearly specified in principle.

  In the above embodiment, for example, the electrolyte membrane of the cell 14 corresponds to the “electrolyte” of the present invention, the anode electrode and the cathode electrode are “a pair of electrodes”, and the air supply manifold 18 is a “supply manifold”. In addition, the air discharge manifold 20 is a “discharge manifold”, the supply screw rotor 30 and the supply rotor 70 are “inlet opening / closing means”, the discharge screw rotor 32 and the discharge rotor 80 are “exit opening / closing means”, and the control device 50 is “ "Control means" respectively. Further, for example, the rotation shafts 60 and 72 are the “rotation shaft” of the inlet opening / closing means in the present invention, the rotation shafts 64 and 82 are the “rotation shaft” of the outlet opening / closing means, and the screw portion 62 is the “spiral” of the inlet opening / closing means. The screw part 66 corresponds to the “spiral member” of the outlet opening / closing means, the semi-disc 74 corresponds to the “rotating member” of the inlet opening / closing means, and the semi-disc 84 corresponds to the “rotating member” of the outlet opening / closing means. .

It is a schematic diagram for demonstrating the structure of the fuel cell system in Embodiment 1 of this invention. It is a schematic diagram for demonstrating the structure of the fuel cell system in Embodiment 1 of this invention. It is a figure for demonstrating the opening-and-closing state of the valve | bulb in the starting mode of the fuel cell in Embodiment 1 of this invention. It is a figure for demonstrating the opening-and-closing state of the valve | bulb in the stop mode of the fuel cell in Embodiment 1 of this invention. In Embodiment 1 of this invention, it is a flowchart for demonstrating the routine of control which the control apparatus of a fuel cell system performs. It is a figure for demonstrating the valve | bulb of the fuel cell in Embodiment 2 of this invention. It is a figure for demonstrating the fuel cell system in Embodiment 2 of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Fuel cell 12 End plate 14 Cell 16 Air flow path 18 Air supply manifold 20 Air discharge manifold 30 Supply screw rotor 32 Discharge screw rotor 34, 36 Motor 40 Air supply pipe 42 Air discharge pipe 44, 46 Pressure sensor 48 Ammeter 50 Control Apparatus 60, 64 Rotating shaft 62, 66 Screw part 70 Supply rotor 80 Discharge rotor 72, 82 Rotating shaft 74, 84 Semi-disc

Claims (13)

A plurality of membrane-electrode assemblies comprising an electrolyte and a pair of electrodes respectively disposed on both sides of the electrolyte;
A plurality of reaction agent channels arranged so as to sandwich the membrane-electrode assembly and provided with a reactant flow channel for allowing the reactant to flow through each of the one electrode on the opposing surface facing the one electrode of the pair of electrodes. A separator;
A supply manifold that penetrates the plurality of separators in the stacking direction and is connected to an inlet of the reactant channel, and that feeds the reactant supplied to the one electrode into the reactant channel;
A discharge manifold that penetrates the plurality of separators in the stacking direction and is connected to an outlet of the reactant flow path, and distributes a waste discharged from the one electrode via the reactant flow path;
An inlet opening / closing means disposed in the supply manifold and changing an opening / closing state of an inlet of the reactant flow path;
An outlet opening / closing means disposed in the discharge manifold and changing an opening / closing state of an outlet of the reactant flow path;
According to the operation mode of the fuel cell, controlling the inlet opening and closing means and the outlet opening and closing means,
When the inlet of the reactant channel is closed, the outlet of the reactant channel is opened, and when the inlet of the reactant channel is opened, the outlet of the reactant channel is closed. A first state,
A second state in which the inlet of the reactant channel and the outlet of the reactant channel are both open or closed;
Control means for switching and controlling;
A fuel cell system comprising: The fuel cell operation mode further includes an activation mode determination means for determining whether or not the operation mode of the fuel cell is an activation mode when starting the stopped fuel cell.
2. The fuel cell system according to claim 1, wherein the control unit performs control so as to be in the second state when it is determined that the start mode is set. 3. The fuel cell operation mode further comprises stop mode determination means for determining whether or not the operation mode of the fuel cell is a stop mode when stopping the fuel cell in the operation state,
3. The fuel cell system according to claim 1, wherein the control unit performs control so as to be in the first state when it is determined that the stop mode is set. 4. A flood detection means for detecting the occurrence of flooding during operation of the fuel cell;
When the flooding is detected, the control means includes a timing at which an inlet of the reactant channel is opened, a timing at which an outlet of the reactant channel is closed or opened, and the reactant. The inlet opening / closing means and the outlet opening / closing are set such that the timing at which the inlet of the flow path is closed and the timing at which the outlet of the reactant flow path is closed or opened are shifted from each other. The fuel cell system according to any one of claims 1 to 3, wherein the means is controlled. During normal operation of the fuel cell,
A power generation amount detecting means for detecting a power generation amount of the fuel cell;
An opening / closing speed setting means for setting a speed for changing the opening / closing state of the inlet of the reactant channel and a speed for changing the opening / closing state of the outlet of the reactant channel according to the power generation amount;
Further comprising
5. The control unit according to claim 1, wherein the control unit controls the opening / closing states of the inlet of the reactant channel and the outlet of the reactant channel to change according to a set speed. The fuel cell system according to claim 1. The inlet opening and closing means is a rotating body rotatably installed in the supply manifold,
The control means controls the opening / closing state of the inlet of the reactant flow path by changing the opening area of the inlet of the reactant flow path by controlling the rotation of the rotating body. Item 6. The fuel cell system according to any one of Items 1 to 5. The inlet opening / closing means includes
A rotating shaft rotatably installed in the supply manifold;
The opening area of the inlet of the reactant flow path is changed by changing the contact area with the inlet of the reactant flow path by being spirally arranged around the rotation axis and rotating with the rotation of the rotary shaft. A spiral member to be changed;
The fuel cell system according to claim 6, further comprising: The inlet opening / closing means includes
A rotating shaft rotatably installed in the supply manifold;
A rotating member that is arranged around the rotating shaft and changes the opening area of the inlet of the reactant flow path by rotating with the rotation of the rotating shaft to change the contact area with the inlet of the reactant flow path. When,
The fuel cell system according to claim 6, further comprising: The outlet opening / closing means is a rotating body rotatably installed in the discharge manifold,
The control means controls the opening / closing state of the outlet of the reactant flow path by changing the opening area of the outlet of the reactant flow path by controlling the rotation of the rotating body. Item 9. The fuel cell system according to any one of Items 1 to 8. The outlet opening / closing means includes
A rotating shaft rotatably mounted on the discharge manifold;
The opening area of the outlet of the reactant channel is changed by changing the contact area with the outlet of the reactant channel by rotating with the rotation of the rotating shaft and changing the contact area with the outlet of the reactant channel. A spiral member,
The fuel cell system according to claim 9, comprising: The outlet opening / closing means includes
A rotating shaft rotatably mounted on the discharge manifold;
A rotating member that is arranged around the rotating shaft and changes the opening area of the outlet of the reactant flow path by rotating with the rotation of the rotating shaft to change the contact area with the outlet of the reactant flow path. When,
The fuel cell system according to claim 9, comprising: The inlet opening / closing means is a rotating body rotatably installed in the supply manifold,
The outlet opening / closing means is a rotating body configured in the same shape as the inlet opening / closing means, and is rotatably installed in the discharge manifold,
The control means controls the first state by setting the rotation of the inlet opening / closing means and the outlet opening / closing means to the same phase, and the rotation of the inlet opening / closing means and the outlet opening / closing means is shifted by 180 degrees. The fuel cell system according to any one of claims 1 to 11, wherein the second state is controlled by setting an opposite phase.   The fuel cell system according to any one of claims 1 to 12, wherein the one electrode is a cathode electrode.

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