JP2005317359A - Fuel cell system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel cell system capable of simply and surely monitoring or diagnosing temporal state change of a fuel cell stack or a cell constituting it. <P>SOLUTION: This fuel cell system 1 is equipped with a fuel cell 10 having fuel cell stacks 13 held between end plates 11 and 12. A fastening part 20 is composed by installing spring units 22 on a plate-like member 21 connected to a barrier rib 14. The fuel cell stacks 13 are fastened by being pressed toward the end plate 11 by the fastening part 20. Position sensors 23 are installed around bases 15. In a calculation control part 30, displacement of the fuel cell stacks 13 is calculated based on position detection signals from the position sensors 23, and determination or the like of the fastening level of the fuel cell stacks 13 can be carried out based on it. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a fuel cell system.

  Fuel cells using a power generation method based on an electrochemical reaction are in the limelight because they have high efficiency and excellent environmental characteristics. Various types of fuel cells have been developed. Among them, there are no problems such as electrolyte dissipation and retention, solid polymer having advantages such as startup at room temperature and extremely fast startup time. Type fuel cells (PEFC: Polymer Electrolyte Fuel Cells) have attracted particular attention and are also used in automotive applications (for fuel cell vehicles).

  PEFC is a stack of at least one cell consisting of a MEA (Membrane Electrode Assembly) and a separator that are integrally joined with a solid polymer electrolyte membrane made of polyethylene or the like sandwiched between two gas diffusion electrodes. Equipped with a stack. One of the gas diffusion electrodes is used as an anode (hydrogen electrode) and hydrogen or hydrogen-rich reformed gas, which is one of the reaction gases, is supplied, and the other gas diffusion electrode is used as a cathode (oxygen electrode) as another reaction gas. A certain oxidizing gas (oxygen or air) is supplied. This causes a hydrogen molecule decomposition reaction in which protons (hydrogen ions) and electrons are generated on the anode surface, and a bond reaction between oxygen and protons that generates water on the cathode surface. The fuel cell stack is sandwiched between end plates provided at both ends in the stacking direction, and is further fastened by pressing at least one of the end plates against the other end plate by an elastic body (usually a spring). ing.

By the way, when operating the fuel cell system in an appropriate state, the state of the fuel cell stack having such a configuration, more specifically, the fastening state thereof, the electrochemical state of the MEA constituting the cell, It is important to monitor and diagnose whether or not the geometric arrangement state of the entire cell or stack is normal. As an example of such state monitoring, Patent Document 1 includes a displacement detection unit that detects a displacement amount of the length in the stacking direction of the fuel cell stack, and a stack temperature detection unit. A fuel cell system that determines the dry state of a solid polymer electrolyte membrane based on the amount of displacement and the stack temperature is described. This system is intended to detect a dry state of a solid polymer membrane that is desired to be sufficiently humidified at a predetermined operating temperature, and to start the system in a swollen state.
JP 2001-332280 A

  However, items that should be monitored and diagnosed for the fuel cell stack are not limited to the dry state of the solid polymer membrane. For example, according to the knowledge of the present inventor, in the structure in which the fuel cell stack is pressed and fastened in the stacking direction with a spring or the like, not only the water content of the solid polymer membrane but also the mechanical force on each cell. Due to the constant application, the dimensional shape of the entire stack may change or be deformed. Further, such deformation is caused by an external force that can damage the cell, and thus affects the electrical and chemical characteristics of the cell and the fuel cell stack. On the other hand, in the above conventional fuel cell system, only the dry state of the solid polymer membrane is indirectly sensed in order to realize optimal control at the start of operation, and various states of the fuel cell stack over time. Changes cannot be monitored and diagnosed.

  Accordingly, the present invention has been made in view of such circumstances, and an object of the present invention is to provide a fuel cell system that can easily and reliably monitor or diagnose a change in the state of a fuel cell stack and the cells constituting the fuel over time. And

  In order to solve the above-described problems, a fuel cell system according to the present invention includes a fuel cell stack in which a plurality of fuel cells are stacked, and a fastening that applies a predetermined load to the fuel cell stack and fastens the fuel cell stack. A displacement detection unit that detects a displacement in the stacking direction of the fuel cell stack, and an arithmetic control unit that determines a fastening degree of the fuel cell stack based on the detected displacement.

  In the fuel cell system configured as described above, a predetermined load is applied to the fuel cell stack by the fastening portion, whereby the fuel cell stack is integrally fastened and held. Specifically, as the fastening portion, an assembly in which a plurality of fuel cells are stacked is sandwiched between end plates provided at both ends in the stacking direction, and a predetermined load is applied from the outside of at least one of the end plates. The thing provided so that it may be mentioned.

  Due to such a fastened state, stress continuously acts on the fuel cell, and creep (material deformation that progresses with time) may occur. As a result, a displacement that causes the entire fuel cell stack to be compressed in the stacking direction occurs. When the displacement of the fuel cell stack increases, for example, in the case of a mechanism in which the fastening portion applies a load to the fuel cell stack by an elastic body such as a spring, the fastening load tends to decrease significantly compared to its initial value. is there. If creep further develops and displacement further increases, it becomes difficult to maintain the load to such an extent that the fuel cell stack cannot be held, and there is a concern that the fuel cell stack may loosen and fall off in some cases.

  Therefore, the calculation control unit can determine the degree of fastening of the fuel cell stack at that time based on the displacement in the stacking direction of the fuel cell stack detected by the displacement detection unit, and is it in a state where inadequate fastening looseness is likely to occur? It is possible to grasp whether or not. Further, by continuously monitoring such a degree of fastening over time, it is possible to accurately predict the occurrence of inconvenient loosening that makes it impossible to hold the fuel cell stack. Therefore, measures such as applying an additional load or reassembling the fuel cell stack can be taken before such loosening occurs. For this purpose, it is preferable that the arithmetic control unit determines a position where the initial fastening load of the fuel cell stack starts to loosen.

  In addition, as a method of determining the fastening degree (state) of the fuel cell stack, it is conceivable to directly measure the fastening load with a load sensor. However, according to the knowledge of the present inventor, when the fastening portion has an elastic body such as a spring and a predetermined load is applied to the fuel cell stack by the pressing force, the displacement due to creep changes. Nevertheless, there may be areas where the load measurements do not change. Therefore, the method of monitoring the degree of fastening with a load sensor has the potential problem that it is difficult to make an accurate determination.

  Alternatively, the fuel cell system according to the present invention is preferably such that the arithmetic control unit determines the performance deterioration state of the fuel cell and / or the fuel cell stack based on the detected displacement.

  When a stress is applied to the fuel cell and creeping occurs, the MEA constituting the fuel cell is locally deteriorated or damaged. For example, the performance is deteriorated due to the micro short circuit due to the electrode damage. obtain. In view of this, in the arithmetic control unit, it is possible to determine the performance deterioration state of the fuel cell, and thus the fuel cell stack, from the measured displacement value of the fuel cell stack detected by the displacement detection unit. Moreover, by monitoring such a performance degradation state over time, it is possible to accurately predict the time when the desired performance required for the fuel cell will not be obtained. Therefore, it is possible to take measures to prevent the performance from decreasing to such an inconvenient level.

  In this case, it is more preferable that the fuel cell stack constitutes a PEFC, and the arithmetic control unit determines deterioration or damage of the MEA provided in the fuel cell as the performance degradation state.

  Alternatively, the fuel cell system according to the present invention includes a fuel cell stack in which a plurality of fuel cells are stacked, a fastening portion that fastens the fuel cell stack by applying a predetermined load to the fuel cell stack, and the fuel cell stack. A displacement detector that detects displacement in the stacking direction at a plurality of different parts, and an arithmetic control part that determines a change in the geometric arrangement of the fuel cells based on the difference in displacement measured at the different parts And may be provided.

  Usually, the fuel cell stack is formed by stacking a plurality of fuel cells so that their extending surfaces (that is, stacked surfaces) are perpendicular or substantially perpendicular to the stacking direction. Therefore, when the fuel cell deviates from the normal stacked state to some extent (for example, when the stacked surface is inclined and deviated from the initial horizontal state), the fuel gas supplied into the fuel cell stack leaks to the outside. There is a risk that.

  In the case where creep caused by continuous stress on the fuel cells does not occur uniformly throughout the fuel cells, but is locally biased, the stacked surfaces of the fuel cells are horizontal. It may be inclined with respect to (the initial stacking direction). In this case, since the entire fuel cell stack can be displaced in the compression direction, there is a concern about gas leakage to the outside as described above. Therefore, by detecting displacements at a plurality of different portions by a plurality of displacement detection units and calculating a difference between actually measured values of the displacements, the geometric arrangement of the entire fuel cell at that time can be detected. Thereby, the change from the geometric arrangement in the initial stacking state of the fuel cells is determined, and gas leakage to the outside can be prevented in advance.

  Here, the “change in geometrical arrangement” includes the above-described inclination from the initial stacking direction (that is, the horizontal degree of the fuel cell), the inclination direction, the occurrence of local curvature and unevenness, and the curvature and unevenness. A state change caused by a change in shape, such as the degree of the above, may be mentioned. Among these, as described above, the level of the fuel cell is a factor deeply related to the leakage (leak) of the fuel gas to the outside. In that sense, it is preferable that the arithmetic control unit determines or detects the level of the fuel cell.

  More specifically, the displacement detector preferably has at least one position sensor (displacement sensor) provided in the fuel cell stack and / or the fastening portion. In either case, a change in the relative position between the fuel cell stack and the fastening portion, that is, a displacement is detected.

  More specifically, the arithmetic control unit obtains the relationship between the previously obtained displacement in the stacking direction of the fuel cell stack and the degree of fastening of the fuel cell stack, or the performance deterioration state of the fuel cell or the fuel cell stack, It is preferable that various determinations are made based on the detected displacement (displacement actual measurement value). By so doing, it is possible to more accurately determine the degree of fastening of the fuel cell stack and the performance degradation state of the fuel cell or fuel cell stack.

  According to the fuel cell system of the present invention, the displacement of the fuel cell stack is detected, and based on this, the state change with time of the fuel cell stack and the cells constituting it can be monitored or diagnosed easily and reliably. Is possible.

  Hereinafter, embodiments of the present invention will be described in detail. In addition, the same code | symbol is attached | subjected to the same element and the overlapping description is abbreviate | omitted. Further, the positional relationship such as up, down, left and right is based on the positional relationship shown in the drawings unless otherwise specified. Further, the dimensional ratios in the drawings are not limited to the illustrated ratios.

  FIG. 1 is a plan view schematically showing a preferred embodiment of a fuel cell system according to the present invention. The fuel cell system 1 is an in-vehicle system mounted on, for example, a fuel cell vehicle, and has a fuel cell stack 13 that is provided so as to be held between the end plates 11 and 12 and fastened by a fastening portion 20. A battery 10 is provided. The fuel cell stack 13 is formed by laminating a plurality of fuel cells made of MEA and a separator made of a carbon material or a metal material. Two fuel cell stacks 13 are provided side by side with a partition wall 14 having one end fixed to the end plate 11, and these are DC-connected.

  The fastening portion 20 is obtained by installing spring units 22 and 22 on a plate-like member 21 connected to the other end of the partition wall 14 on the end plate 12 side. The spring units 22 and 22 are provided so that the tip portions of the springs 22a and 22a are in contact with the pedestals 15 and 15 provided on the outer surface of the end plate 12, respectively. The springs 22a and 22a are compression springs, and the end plate 12 is pressed against the end plate 11 side by the spring units 22 and 22 so that the fuel cell stacks 13 and 13 are clamped between the end plates 11 and 12. Retained. The material and form of the springs 22a and 22a are not particularly limited, and examples of the material include metal springs such as iron and copper springs and non-ferrous metal springs, resin springs, rubber springs, fluid springs, and the like. Non-metallic springs. Moreover, as the form, a disc spring, a spring spring, a leaf | plate spring, etc. are mentioned.

  Further, position sensors 23 and 23 (displacement detection units) are provided around the pedestal 15 on the outer side surface 12a of the end plate 12. Each position sensor 23 is provided so as to face the side wall surface of the partition wall 14, and the side wall surface of the partition wall 14 measures the position of the position sensor 23 with respect to the end plate 12 in the cell stacking direction of the fuel cell stack 13. It fulfills the function of a gauge that serves as a reference. Further, an arithmetic control unit 30 is connected to the position sensors 23 and 23, and position information or displacement information measured by the position sensors 23 and 23 is input to the arithmetic control unit 30. Here, FIGS. 2A to 2E are diagrams each showing a main part of a cross section taken along the line II-II in FIG. 1, and show various examples in which the number and location of the position sensors 23 are different. Is.

  FIG. 2A shows a form (corresponding to FIG. 1) in which one position sensor 23 is provided in each of the fuel cell stacks 13 and 13. FIG. 2B shows a form in which two position sensors 23 are arranged opposite to each other in accordance with each fuel cell stack 13. Further, FIGS. 2C to 2E show a form in which four position sensors 23 are arranged according to each fuel cell stack 13, and the arrangement patterns are different from each other.

  Here, FIG. 3 is a plan view showing a state in which the fuel cell stack 13 is fastened, and shows a part of FIG. In the fuel cell system 1, a predetermined load corresponding to the pressing force of the spring 22 a provided in the spring unit 22 is applied from the end plate 12 side to the fuel cell stack 13 in the stacking direction. The fastening state of the fuel cell stack 13 is maintained by the load, and stress corresponding to the applied load continuously acts on the fuel cells constituting the fuel cell stack 13. As a result, stress is exerted on the fuel cell so that the fuel cell is compressed in the direction of the arrow X shown in the figure, and creep can progress.

  When creep occurs in an individual fuel cell, a displacement is caused such that the entire fuel cell stack 13 is compressed in the stacking direction. Accordingly, while the spring 22a is extended, the contact between the spring 22a and the base 15 is maintained, and the fastening state of the fuel cell stack 13 can be maintained for a certain period by the pressing force. However, if the creep further progresses, the displacement (distance D shown in FIG. 3) of the fuel cell stack 13 from the initial state may become excessively large, and the fastening of the fuel cell stack 13 will be unnecessarily loosened eventually, and the fuel It becomes difficult to hold the battery stack 13.

  At this time, in the fuel cell system 1, the relative position of the fuel cell stack 13 with respect to the fastening portion 20 is continuously measured by the position sensor 23, and the measurement value signal is continuously or intermittently transmitted to the arithmetic control unit 30. Sent out. In the arithmetic control unit 30, the displacement D from the initial state of the fuel cell stack 13 is calculated based on the measurement value signal from the position sensor 23. Thus, the displacement D of the fuel cell stack 13 is detected by the position sensor 23.

  Here, FIG. 4 is a graph showing an example of the relationship between the displacement of the fuel cell stack 13 and the measurement signal value of the position sensor 23 (the relationship represented by the solid line L1 in the figure). Also, in the figure, for reference, when a disc spring is used as the spring 22a, the load sensor measured signal value when the load applied to the fuel cell stack 13 by the spring unit 22 is measured by the load sensor, A graph showing the relationship with the displacement of the fuel cell stack 13 is indicated by a broken line L2.

  From the solid line L1 shown in FIG. 4, the displacement of the fuel cell stack 13 and the measurement signal value of the position sensor 23 tend to be linear and have a good correlation. Therefore, according to the fuel cell system 1, the displacement D of the fuel cell stack 13 can be accurately calculated by the position sensor 13. On the other hand, from the broken line L2 shown in FIG. 4, the measurement signal value of the load sensor and the displacement of the fuel cell stack 13 do not have a linear correlation. That is, there is a range in which the load is substantially constant even when the displacement of the fuel cell stack 13 changes. In this case, in such a range, it is extremely difficult to accurately calculate the displacement of the fuel cell stack 13 even if the load is actually measured by the load sensor.

  Further, the arithmetic control unit 30 has a relationship between the degree of fastening of the fuel cell stack 13 and the displacement acquired in advance, specifically, the degree of fastening between the fuel cell stack 13 and the fastening unit 20 changes as the displacement increases. As a result, the looseness of the fastening tends to increase, and the relationship specific to the fuel cell stack 13 is stored or input. Then, from the relationship and the measured value of the displacement D, the degree of fastening of the fuel cell stack 13 at that time is determined.

  At this time, according to the fuel cell system 1, since the displacement of the fuel cell stack 13 can be accurately detected as described above, the degree of fastening between the fuel cell stack 13 and the fastening portion 20 at that time can be accurately determined. Further, by performing such a determination over time, the degree of fastening can be monitored at all times, and the progress of the degree of fastening reduction, in other words, the progress of the loosening of the fastening can be grasped, which is inconvenient for the fuel cell stack 13. It is also possible to predict the position or timing at which a loose fastening will occur. Therefore, it is possible to grasp in advance that excessive fastening looseness that may cause the fuel cell stack 13 to drop out occurs. Therefore, it is possible to take measures such as applying an additional load, refastening the fuel cell stack 13, and reassembling before such loosening occurs.

  Further, the arithmetic control unit 30 has a relationship between the previously acquired performance degradation state of the fuel cell and the fuel cell stack 13 and the displacement, specifically, if the displacement increases, the fuel cell and the fuel cell stack 13 There is a tendency for performance degradation, such as output degradation, to increase, and the relationship unique to the fuel cell stack 13 is also stored or input. Then, from the relationship and the measured value of the displacement D, the performance deterioration state of the fuel cell and the fuel cell stack 13 at that time is determined.

  Regarding the performance degradation of the fuel cell and the fuel cell stack 13, more specifically, when a stress is applied to the fuel cell constituting the fuel cell stack 13 and creep occurs, the MEA constituting the fuel cell locally It may be damaged. For example, an adverse electrical event such as a micro short circuit may occur due to damage to the electrodes of the MEA, and as a result, the performance of the fuel cell and thus the fuel cell 10 may deteriorate. Here, FIG. 5 is a graph (illustrated solid line L3) schematically showing the relationship between the displacement of the fuel cell stack 13 and the damage of the MEA (as a damage degree, for example, the deterioration of electrical characteristics is quantified). Thus, the MEA damage tends to increase as the creep amount increases.

  Also in this case, according to the fuel cell system 1, since the displacement of the fuel cell stack 13 can be accurately detected as described above, it is possible to accurately determine whether or not the MEA is deteriorated or damaged, or the degree thereof. Therefore, it becomes possible to determine the state of performance degradation of the fuel cell and thus the fuel cell stack 13 due to such deterioration or damage of the MEA. In addition, by performing the determination of the performance degradation state over time, it is possible to predict and determine the occurrence and timing of a situation that would result in lower than the performance required for the fuel cell 10, Can be taken as appropriate.

  Further, when a plurality of position sensors 23 are provided as shown in FIGS. 2B to 2E, displacement detection signals from the respective position sensors 23 are independently sent to the calculation control unit 30, and the calculation control unit 30. Then, each displacement D in the site | part in which each position sensor 23 was installed is calculated. When the creep that causes the fuel cell stack 13 to be uniformly displaced in the compression direction (the arrow X direction shown in FIG. 3) occurs on the stack surface of the fuel cells, the end plate 12 can maintain the initial levelness. No substantial difference occurs in each displacement D. On the other hand, when creep occurs locally on the stack surface of the fuel cell, the stack surface cannot maintain the initial level, so that the fuel gas supplied to the fuel cell stack 13 is stacked. There is a risk of leakage from the site where the abnormality occurred.

  Therefore, the arithmetic control unit 30 obtains the difference between the displacements D calculated based on the outputs from the plurality of position sensors 23, so that the inclination of the fuel cell at the time, that is, the horizontality (horizontal) Degree) can be determined or detected. Alternatively, it is possible to calculate a deviation from the initial level of the fuel cell, that is, a relative change in the level. Then, for example, the level of the fuel cell that may cause the leakage of the fuel gas to the outside is grasped in advance, and in the arithmetic control unit 30, such pre-acquired data and the level of the fuel cell are determined. It is possible to monitor the state of the fuel cell stack 13 by comparing the measured value with the actual measurement value of the fuel cell stack. In addition, by performing this over time, it is possible to perform in advance an inconvenient state change that may cause gas leakage to the outside. Therefore, it is possible to prevent such gas leakage.

  In addition, when a plurality of position sensors 23 are provided, it is possible to determine the inclination direction of the fuel cell, and it is easy to specify the uneven distribution site in the stacking surface of the fuel cell. Further, depending on the number of position sensors 23 installed, there is an advantage that it becomes easy to grasp the occurrence of a local curve or unevenness in the stacked surface of the fuel cells, the degree of the curve or unevenness, and the like. It should be noted that these items determined and detected from the displacement measurement by the position sensor 23 are one of the changes in the geometric arrangement caused by the change in the shape of the fuel cell.

  FIG. 6 is a plan view schematically showing another preferred embodiment of the fuel cell system according to the present invention. In the fuel cell system 2, position sensors 43 and 43 (displacement detection units) are installed at portions of the partition wall 14 between the end plate 12 and the plate-like member 21 instead of the position sensors 23 and 23, and face each of them. As described above, the fuel cell system 1 is configured in the same manner as the fuel cell system 1 shown in FIG. 1 except that a gauge 41 is provided between the base 15 and the partition wall 14. Further, the position sensors 43 and 43 are connected to the calculation control unit 30. Further, the gauge 41 is used as a reference for measuring the position of the position sensor 43 relative to the end plate 12 in the cell stacking direction of the fuel cell stack 13.

  Also in the fuel cell system 2 configured in this way, the displacement D of the fuel cell stack 13 is calculated from the position detection signal measured by the position sensor 43, and based on the displacement D, the same as described above, Determination of the degree of fastening of the fuel cell stack 13 at that time, determination of the performance degradation state of the fuel cell and the fuel cell stack 13, and monitoring of those over time, and prediction of whether an unfavorable situation will occur realizable. Further, by installing a plurality of position sensors 43 for each fuel cell stack 13, the difference between the displacements D calculated based on the output from each position sensor 43 is obtained, and the geometrical arrangement of the fuel cells. It is possible to determine the change of the gas and monitor it over time, and predict and prevent the occurrence of, for example, a gas leak based on the results.

  In addition, this invention is not limited to embodiment mentioned above, A various deformation | transformation is possible in the limit which does not change the summary. For example, the position sensors 23 and 43 are installed facing the plate-like member 21 of the fastening portion 20, the relative positions of the position sensors 23 and 43 with respect to the plate-like member 21 are detected, and the fuel cell is determined from the change over time. The displacement D of the stack 13 may be calculated. Further, in the fuel cell systems 1 and 2, the position sensors 23 and 43 and the load sensor may be used together, and the load control value from the load sensor may be subjected to data processing in the arithmetic control unit 30.

  According to the fuel cell system of the present invention, the displacement of the fuel cell stack caused by the continuous load application from the fastening portion is measured, and based on the result, various fuel cell stacks and various fuel cell stacks are measured. Judgment and status monitoring are possible, and occurrence of defects can be predicted and prevented in advance. Therefore, it can be widely used for equipment, motives, facilities, and the like that are equipped with a fuel cell system such as a fuel cell vehicle and a fuel cell power generation facility.

1 is a plan view schematically showing a preferred embodiment of a fuel cell system according to the present invention. 2 (A) to 2 (E) are views showing the main part of the cross section taken along line II-II in FIG. 1, respectively. It is a top view which shows the state by which the fuel cell stack 13 is fastened. 6 is a graph showing an example of the relationship between the displacement of the fuel cell stack 13 and the measurement signal value of the position sensor 13. 6 is a graph schematically showing the relationship between the displacement of the fuel cell stack 13 and the MEA damage. FIG. 5 is a plan view schematically showing another preferred embodiment of the fuel cell system according to the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1, 2 ... Fuel cell system, 10 ... Fuel cell, 11, 12 ... End plate, 12a ... Outer side surface, 13 ... Fuel cell stack, 14 ... Partition, 15 ... Base, 20 ... Fastening part, 21 ... Plate-shaped member, 22 ... Spring unit, 23, 43 ... Position sensor (displacement detection unit), 30 ... Calculation control unit, 41 ... Gauge, D ... Displacement.

Claims (9)

A fuel cell stack formed by stacking a plurality of fuel cells, and
A fastening portion that fastens the fuel cell stack by applying a predetermined load to the fuel cell stack;
A displacement detector for detecting displacement in the stacking direction of the fuel cell stack;
An arithmetic control unit that determines the degree of fastening of the fuel cell stack based on the detected displacement;
A fuel cell system comprising: A fuel cell stack formed by stacking a plurality of fuel cells, and
A fastening portion that fastens the fuel cell stack by applying a predetermined load to the fuel cell stack;
A displacement detector for detecting displacement in the stacking direction of the fuel cell stack;
An arithmetic control unit for determining a performance degradation state of the fuel cell and / or the fuel cell stack based on the detected displacement;
A fuel cell system comprising: A fuel cell stack formed by stacking a plurality of fuel cells, and
A fastening portion that fastens the fuel cell stack by applying a predetermined load to the fuel cell stack;
A displacement detector that detects displacement in the stacking direction of the fuel cell stack at a plurality of different locations;
An arithmetic control unit that determines a change in the geometric arrangement of the fuel cells based on a difference in displacement measured at the plurality of different parts;
A fuel cell system comprising: The displacement detection unit has at least one position sensor provided in the fuel cell stack and / or the fastening unit.
The fuel cell system according to any one of claims 1 to 3.   The fuel cell system according to claim 1, wherein the arithmetic control unit determines a position where an initial fastening load of the fuel cell stack starts to loosen. The arithmetic control unit determines or detects the level of the fuel cell.
The fuel cell system according to claim 1 or 3. The arithmetic control unit performs the determination based on the relationship between the displacement in the stacking direction of the fuel cell stack acquired in advance and the fastening degree of the fuel cell stack, and the detected displacement.
The fuel cell system according to claim 1. The arithmetic control unit is based on the relationship between the displacement in the stacking direction of the fuel cell stack acquired in advance and the performance deterioration state of the fuel cell and / or the fuel cell stack, and the detected displacement. The determination is performed.
The fuel cell system according to claim 2. The fuel cell stack constitutes a polymer electrolyte fuel cell;
The arithmetic control unit determines deterioration or damage of MEA provided in the fuel cell as the performance degradation state.
The fuel cell system according to claim 2.

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