JP4136443B2 - Fuel cell - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an improvement of a fuel cell, particularly a polymer electrolyte fuel cell.
[0002]
[Prior art]
A fuel cell is usually configured as a fuel cell stack in which a plurality of cells are stacked. In such a fuel cell stack, the cells are fixed by tightening end plates arranged at both ends in the cell stacking direction with tightening bolts. In this case, the load applied to each cell is detected as an axial force of the fastening bolt by a strain gauge or the like attached to the fastening bolt. Such an example is described in Japanese Patent Application Laid-Open No. 2001-325985.
[0003]
[Problems to be solved by the invention]
However, in the above conventional load detection method, the axial force of the fastening bolt is detected, not the load or pressure directly applied to each cell. For this reason, there is a problem that the load applied to each cell cannot be accurately known and the fastening force of the fuel cell stack cannot be accurately adjusted. For this reason, there is a problem that the fastening force of the fuel cell stack is too low, and the contact resistance between the separator and the diffusion layer increases or gas leakage is likely to occur. Conversely, if the fastening force becomes too large, the electrolyte membrane constituting the polymer electrolyte fuel cell may be damaged.
[0004]
The present invention has been made in view of the above-described conventional problems, and an object thereof is to provide a fuel cell capable of accurately detecting the fastening force of a cell.
[0005]
[Means for Solving the Problems]
In order to achieve the above object, the present invention provides an electrolyte membrane, a pair of catalyst layers disposed on both sides of the electrolyte membrane, a pair of diffusion layers disposed outside the catalyst layer, and the diffusion layers. A fuel cell in which a plurality of cells each composed of a pair of separators arranged on the outside are stacked, and a load detecting means for detecting a load applied to an electrolyte membrane constituting the cell includes the diffusion layer and the catalyst layer Embedded in the separator facing the electrolyte membrane via
[0007]
In the fuel cell, the separator includes a recess serving as a gas passage, and a projection that protrudes from the recess and contacts the diffusion layer, and is at least a part of the load detection unit embedded in the separator. Is arranged in the separator so as to face a surface where the convex portion and the diffusion layer are in contact with each other.
[0008]
According to the above configuration, the load detecting means, so are embedded in the separator which faces the electrolyte membrane via the diffusion layer and the catalyst layer, it is possible to accurately detect the load applied to the electrolyte membrane.
[0009]
The fuel cell is characterized by comprising means for controlling the load applied to the electrolyte membrane based on the detection result of the load detection means.
[0010]
According to the above configuration, the load applied to the electrolyte membrane can be accurately controlled.
[0011]
The fuel cell may further include a load alarm that issues an alarm when the detection result of the load detection means exceeds a predetermined value.
[0012]
According to the said structure, it can monitor so that the load added to an electrolyte membrane may not exceed predetermined value.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention (hereinafter referred to as embodiments) will be described with reference to the drawings.
[0014]
FIG. 1 shows a configuration example of a fuel cell according to the present invention. In FIG. 1, a polymer electrolyte fuel cell stack 1 is formed by stacking a plurality of cells 11. A fixed end plate 10 is provided on one side of the laminate, and a movable plate 12 is arranged on the other side. The movable plate 12 is pressed by a cylinder 13 from the opposite side of the stacked body of cells 11. The cylinder 13 is pressurized by a cylinder pressurizing unit 18 supported by another fixed end plate 16, and the cell 11 constituting the laminate is pressurized via the movable plate 12 by this applied pressure. These fixed end plates 10 and 16 are fixed to the fastening rod 14 by fixing means 15 such as bolts. The movable plate 12 is not fixed to the fastening rod 14 and is attached to the fastening rod 14 so as to be movable in parallel to the axial direction.
[0015]
The fixed end plate 16 is provided with a cylinder control device 17, and the cylinder control device 17 controls the cylinder pressurizing unit 18 in accordance with a signal from the ECU 26. The cylinder pressurizing unit 18 applies a load to the cell 11 by moving the cylinder 13 in and out in a direction parallel to the fastening rod 14 while being controlled by the cylinder control device 17.
[0016]
A characteristic point in the present embodiment is that a load detecting means 19 for detecting a load applied to the cell 11 is provided in at least one of the stacked surfaces of the stacked cells 11. Note that the load detecting means 19 may be disposed at a plurality of locations on different laminated surfaces or the same laminated surface. The number of load detection means 19 can be determined as appropriate depending on the shape, size, etc. of the polymer electrolyte fuel cell stack 1. Since the load detection means 19 is arranged on the stacked surface of the cells 11 as described above, the load applied to the cells 11 can be directly detected, so that an accurate load can be known.
[0017]
An output signal from the load detection means 19 is input to the ECU 26. The ECU 26 controls the cylinder control device 17 based on the load detection result input from the load detection means 19, and the cylinder control device 17 drives the cylinder pressurizing unit 18 to appropriately determine the position of the cylinder 13, The load applied to the cell 11 is appropriately controlled.
[0018]
Hereinafter, the operation of controlling the load on the cell 11 in the polymer electrolyte fuel cell stack 1 shown in FIG. 1 will be described.
[0019]
When starting the fuel cell, before introducing the fuel gas into the polymer electrolyte fuel cell stack 1, the cylinder pressurizing unit 18 presses the cylinder 13 against the movable plate 12, thereby applying a load to the cell 11. At this time, based on the detection signal of the load detection means 19, the pressure applied to the cylinder pressurizing unit 18 is controlled so that the cell 11 is not damaged and the fastening load is such that the gas sealing property can be secured. Thereby, even in a state where the apparatus temperature is low and the member is contracted, the gas sealing performance can be ensured without applying an excessive fastening force.
[0020]
Next, when the fuel cell is in an operating state, heat is generated inside the cell due to IR loss or the like, so that the device temperature rises. As the temperature rises, the constituent members of the battery expand, so that the fastening load changes depending on the temperature distribution of the device, the difference in the thermal expansion coefficient between the fastening rod 14 and the laminate of the cells 11, and the like. In this case, based on the load detected by the load detection means 19, a command is issued from the ECU 26 to the cylinder control device 17, the cylinder pressurization unit 18 is controlled by the cylinder control device 17, and the cell 13 is transferred to the cell 11. The pressing force is appropriately controlled. Thereby, the cell 11 is not damaged, the gas sealing property can be ensured, and the load capable of reducing the contact resistance can be maintained.
[0021]
If the use of the polymer electrolyte fuel cell 10 is continued, the component member is deformed by creep and the fastening force decreases. According to this embodiment, the load change in this case Can also be detected by the load detection means 19 and can be adjusted as appropriate to maintain a constant fastening force.
[0022]
Further, it is also preferable to provide a load alarm 27 that outputs an alarm signal from the ECU 26 when the load detected by the load detection means 19 exceeds a predetermined value, thereby issuing an alarm.
[0023]
FIG. 2 shows a cross-sectional view of the cells 11 constituting the polymer electrolyte fuel cell stack 1. In FIG. 2, in the cell 11, an anode catalyst layer 23 and a cathode catalyst layer 24 are disposed on both sides of the electrolyte membrane 20, and an anode diffusion layer 21 and a cathode diffusion layer 22 are disposed outside thereof. Further, a separator 25 is disposed outside thereof. A gas passage 28 is formed in the separator 25.
[0024]
The load detection means 19 is embedded in the separator 25. In the example shown in FIG. 2, the load detection means 19 is disposed at a position facing the electrolyte membrane 20 through a portion where the separator 25 and the cathode diffusion layer 22 are in contact with each other. . In this case, the load detection means 19 also constitutes one wall of the gas passage 28 provided in the separator 25. With such an arrangement, the load applied to the electrolyte membrane 20 by the separator 25 can be directly detected by the load detection means 19. A material whose resistance value changes depending on the applied load, such as Ni—Cr—alumina cermet, is formed on the surface of the load detecting means 19.
[0025]
FIG. 2 shows an example in which the load detecting means 19 is embedded in the separator 25. However, since the fastening load applied to the cell 11 has a normal distribution, the load, etc., with the highest load as a representative point is shown. The detection means 19 is preferably arranged. Depending on the shape, size, etc. of the cells, a plurality of load detecting means 19 are arranged on the same laminated surface or different laminated surfaces, and the load applied to the laminated surface of each cell 11 is detected by the plurality of load detecting means 19. It is also suitable to do.
[0026]
Further, as shown in FIG. 2, the load detecting means 19 may be disposed at a contact portion of the separator 25 with the electrolyte membrane 20, but is not necessarily limited thereto. For example, you may install in the gas seal site | parts, such as a peripheral part instead of the center site | part of the cell 11 outside the separator 25, ie, another cell 11, or the center site | part.
[0027]
Since the temperature of the fuel cell varies between when it is activated and when it is stopped, it is also preferable to dispose a temperature measuring means near the load detecting means 19 in order to correct the temperature characteristics of the load detecting means 19. Thereby, a load can be detected with higher accuracy. As the temperature in this case, the gas temperature or the cooling water temperature can be substituted.
[0028]
As described above, the load applied to the polymer film 20 of the cell 11 can always be accurately detected even if the use condition and the environmental condition change, and the load can be controlled based on this, so that excessive fastening is possible. It is possible to maintain an optimum fastening load that does not damage the cell 11, particularly the polymer film 20, with the load, can ensure gas sealing properties, and reduce contact resistance.
[0029]
【The invention's effect】
As described above, according to the present invention, the load applied to the cell can be accurately detected, and the load applied to each cell can be optimally controlled by the detected load. As a result, it is possible to ensure the gas sealing property without damaging the cell and to further reduce the contact resistance.
[0030]
In addition, by providing a load alarm that issues a warning when the detected load exceeds a predetermined value, the operation of the fuel cell can be performed more safely.
[Brief description of the drawings]
FIG. 1 is a diagram showing a configuration of a fuel cell according to the present invention.
FIG. 2 is a cross-sectional view of the cell used in FIG.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Solid polymer fuel cell stack 10, 16 Fixed end plate, 11 cells, 12 Movable plate, 13 Cylinder, 14 Fastening rod, 15 Fixing means, 17 Cylinder control apparatus, 18 Cylinder pressurization part, 19 Load detection means, 20 electrolyte membrane, 21 anode diffusion layer, 22 cathode diffusion layer, 23 anode catalyst layer, 24 cathode catalyst layer, 25 separator, 26 ECU, 27 load alarm, 28 gas passage.

Claims (5)

A cell comprising an electrolyte membrane, a pair of catalyst layers disposed on both sides of the electrolyte membrane, a pair of diffusion layers disposed outside the catalyst layer, and a pair of separators disposed outside the diffusion layer Is a stacked fuel cell,
A load detection means for detecting a load applied to the electrolyte membrane constituting the cell is embedded in the separator facing the electrolyte membrane via the diffusion layer and the catalyst layer. Fuel cell. 2. The fuel cell according to claim 1, wherein the separator includes a concave portion serving as a gas passage, and a convex portion protruding from the concave portion and in contact with the diffusion layer,
At least a part of the load detection means embedded in the separator is disposed in the separator so as to face a surface where the convex portion and the diffusion layer are in contact with each other.   3. The fuel cell according to claim 1, further comprising means for controlling a load applied to the electrolyte membrane based on a detection result of the load detection means.   The fuel cell according to any one of claims 1 to 3, further comprising a load alarm that issues a warning when a detection result of the load detection means exceeds a predetermined value.   5. The fuel cell according to claim 1, wherein temperature measuring means for measuring a temperature of a cell is disposed near the load detecting means, and the load is measured based on the temperature measured by the temperature measuring means. A fuel cell, wherein the temperature characteristic of the detecting means is corrected.

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