JP4060257B2 - A fuel cell having a connection structure between a terminal on the cell voltage measuring device side and a terminal on the fuel cell side - Google Patents

Description

The present invention relates to a fuel cell having a connection structure between terminals on a cell voltage measuring device side and terminals on a fuel cell side.

In the fuel cell, for example, a solid polymer electrolyte membrane is sandwiched between an anode side electrode and a cathode side electrode from both sides, and a separator is provided on the outer side to constitute a unit fuel cell (hereinafter referred to as “unit cell”). There is.
In order to secure the generated voltage, this type of fuel cell often has a plurality of unit cells stacked to form a fuel cell stack (hereinafter referred to as “stack”) in actual use. In order to monitor the power generation state of each unit cell, it is necessary to measure the cell voltage.

Since conventional conductive materials such as carbon and metal have been used for conventional separators (hereinafter referred to as “conductive separators”), by forming a part of the separator into the shape of a cell voltage measuring terminal, or A cell hole could be easily measured from the outside by making a round hole in the outer peripheral surface of the electrode and connecting one end of the output terminal to the round hole with a banana clip (see, for example, Patent Document 1).
JP-A-9-283166

  However, when a stack is formed using this conductive separator, there is a possibility that an electric leakage (liquid junction) or a ground fault may occur through the cooling water (refrigerant) flow path due to a potential difference between unit cells. The cooling water is required to have a high degree of insulation, and it is necessary to install an ion exchanger in order to remove conductive ions.

As a countermeasure, in recent years, a conductive material such as a metal is used for a portion in contact with the electrode (electrode surface portion), and a portion other than the electrode surface portion, that is, a portion where the reaction gas and cooling water communication holes are formed in the outer peripheral portion of the electrode surface portion A so-called composite separator using an insulating material is proposed.
When a stack is configured using this composite separator, the cooling water edge surface distance (insulation distance) between unit cells becomes long, so that high insulation is not required for the cooling water. Rust generation can also be suppressed. Furthermore, since the outer edge portion of the separator is made of an insulating material, a ground fault with the outside can be effectively prevented.

As described above, the composite separator has an insulating structure on the outer side in the surface direction of the electrode surface portion (separator outer peripheral side), so that it is possible to effectively prevent a liquid junction due to cooling water or an external ground fault. On the other hand, it has the disadvantage that it becomes very difficult to measure the cell voltage.
Under such circumstances, it is desired to develop a technique that can monitor the power generation state of each unit cell while preventing liquid junction and ground fault.

  The present invention has been made in view of the above circumstances, and an object thereof is to make it possible to easily measure a cell voltage from the outside while preventing a liquid junction of a refrigerant and a ground fault with the outside. is there.

In order to solve the above problems, the present invention employs the following means.
The invention according to claim 1 is a connection between terminals on a cell voltage measuring device side (for example, a measurement side terminal 61 in an embodiment described later) and a fuel cell (for example, a unit cell 1 in an embodiment described later) side. A fuel cell having a structure,
In the fuel cell, a conductive portion (for example, conductive portions 31 and 41 in an embodiment described later) having an electrode surface portion (for example, electrode surface portions 31A and 41A in an embodiment described later) is an insulating portion (for example, implementation described later). A pair of separators (for example, a cathode-side separator 3 and an anode-side separator 4 in an embodiment described later) are surrounded by an insulating portion 32, 42 in the embodiment of FIG. A membrane electrode structure (for example, a membrane in an embodiment described later) provided with electrodes (for example, a cathode side gas diffusion electrode 22 and an anode side gas diffusion electrode 23 in an embodiment described later) on both sides of the molecular electrolyte membrane 21) The electrode structure 2) is sandwiched between at least one insulating portion of the pair of separators, The inner and outer connection terminals (for example, the inner peripheral side end portion 47a in the embodiment described later) are in contact with the membrane electrode structure or the conductive portion. A cell side terminal 47) in an embodiment to be described later,
The terminal on the cell voltage measuring device side (for example, the measuring side terminal 61 in the embodiment described later) is inserted between the insulating portions of the pair of separators facing each other in an elastically compressed state in the gap direction. A terminal electrode (for example, a terminal electrode 65 in an embodiment described later) that presses the outer peripheral side end of the inner and outer connecting terminals by an elastic restoring force is provided.

According to this inter-terminal connection structure, an electrical connection between the inside and outside of the fuel cell is ensured even when measuring the cell voltage, even for a fuel cell in which a ground fault is prevented from occurring by the insulating portion.
Moreover, since sufficient contact pressure is ensured between the terminal electrode by the side of a cell voltage measuring apparatus, and the outer peripheral side edge part of an internal / external connection terminal, contact resistance also falls.
Furthermore, the reliability of the electrical connection is maintained even for disturbances such as vibration and impact that cause the terminal electrode on the cell voltage measuring device side to be relatively separated from the fuel cell.

The invention according to claim 2 is a fuel cell having the cell voltage measuring device side terminal and the fuel cell side terminal connecting structure according to claim 1,
The insulating portion includes a communication hole through which a reaction gas or a refrigerant flows (for example, an inlet-side oxidant gas communication hole 34a, an outlet-side oxidant gas communication hole 34b, an inlet-side fuel gas communication hole 35a, an outlet in an embodiment described later) A side fuel gas communication hole 35b, an inlet side cooling water communication hole 36a, and an outlet side cooling water communication hole 36b).

  According to this configuration, the potential can be easily taken out from the outside while effectively preventing the liquid junction caused by the refrigerant flowing through the communication hole by the insulating portion.

According to the present invention, the following effects are obtained.
According to the first aspect of the present invention, the terminal on the cell voltage measuring device side is connected to the outer peripheral side end of the internal / external communication terminal even for the fuel cell in which the grounding prevention from the outside is performed by the insulating portion. Since electrical connection inside and outside the fuel cell is secured, the potential can be easily taken out from the outside.
In addition, the reliability of electrical connection is ensured against disturbances such as vibration and shock that cause the terminal on the cell voltage measuring device side to be relatively separated from the fuel cell, so cell voltage measurement is performed with high accuracy. be able to.
Furthermore, since a sufficient contact pressure can be ensured between the terminal electrode on the cell voltage measuring device side and the outer peripheral side end of the internal / external connection terminal, the contact resistance can be lowered.

  According to the second aspect of the present invention, the potential can be easily taken out from the outside while effectively preventing the liquid junction caused by the refrigerant flowing through the communication hole by the insulating portion.

The best mode for carrying out the present invention will be described below with reference to the accompanying drawings.
FIG. 3 is a longitudinal sectional view showing a state before the terminal on the cell voltage measuring device side is connected to the terminal on the fuel cell stack side.
A unit fuel cell (hereinafter referred to as “unit cell 1”) includes a membrane electrode structure (MEA) 2 and a cathode side separator 3 and an anode side separator 4 sandwiching the membrane electrode structure (MEA) 2. A large number of unit cells 1 are stacked to form, for example, a vehicle fuel cell stack (hereinafter referred to as “stack 5”).

The membrane electrode structure 2 includes a solid polymer electrolyte membrane 21, a cathode side gas diffusion electrode 22 and an anode side gas diffusion electrode 23 that sandwich the solid polymer electrolyte membrane 21 from the outside, and these solid polymer electrolyte membranes 21. It comprises a catalyst layer (not shown) containing platinum provided between the cathode side and anode side gas diffusion electrodes 22, 23.
The membrane electrode structure 2 is a step structure in which the cathode side gas diffusion electrode 22 has substantially the same size, but the anode side gas diffusion electrode 23 has a small size, based on the outer dimensions of the solid polymer electrolyte membrane 21. I am doing.

Each of the cathode side separator 3 and the anode side separator 4 surrounds the outer periphery of the conductive parts 31 and 41 made of metal (for example, stainless steel, Hastelloy, Inconel, Au, Cu, Ni, Al, Ti, etc.). The provided insulating parts 32 and 42 made of resin are interconnected.
This interconnection may be connected through a coupling portion made of an elastic material such as silicon rubber for the purpose of absorbing a difference in thermal expansion between the conductive portions 31 and 41 and the insulating portions 32 and 42, for example. In this case, not only the structure in which the conductive portions 31 and 41 and the insulating portions 32 and 42 are completely separated by the coupling portion, but at least a part of the conductive portions 31 and 41 have entered the insulating portions 32 and 42. It may be a structure.

Each of the conductive portions 31 and 41 on the cathode side and the anode side is formed in a cross-sectional waveform in which flat peaks and valleys are alternately continued by press-molding a metal plate. The valley outer surfaces of the conductive portions 31 and 41 are in surface contact with the outer surfaces of the membrane electrode structure 2 sandwiched between them,
The contact surfaces constitute electrode surface portions 31A and 41A in the separators 3 and 4, respectively.
These conductive parts 31 and 41 are not limited to being made of metal, but may be made of a conductive material such as carbon or conductive resin.

As shown in FIG. 4, the insulating portions 32 and 42 of the cathode-side and anode-side separators 3 and 4 are formed by injection molding of resin and spaced in the circumferential direction at the inlet-side oxidant gas communication holes 34a and outlet-side oxidation. It is formed in a rectangular frame shape having an agent gas communication hole 34b, an inlet side fuel gas communication hole 35a, an outlet side fuel gas communication hole 35b, an inlet side cooling water communication hole 36a, and an outlet side cooling water communication hole 36b. FIG. 4 shows the cathode separator 3.
These insulating parts 32 and 42 are not limited to resin, but may be made of an insulating material such as rubber, silicon or ceramics.

A cell side terminal (internal / external connection terminal) 47 that enables electrical connection (conduction) inside and outside the cell is provided on the inner surface side of the cathode side insulating portion 32.
The cell-side terminal 47 has a resin part 32a that is the main body of the cathode-side insulating part 32 formed in advance by injection molding or the like, and a conductive material is partially plated on the resin part 32a or deposited by PVD or CVD. It is provided by performing various surface treatments such as.

  The arrangement position of the cell side terminal 47 in the resin portion 32a is such that the cooling water communication is effective from the viewpoint of effectively preventing the liquid junction of the cooling water (refrigerant) flowing through the inlet side and outlet side cooling water communication holes 36a and 36b. It is preferable to keep away from the periphery of the holes 36a and 36b, and in this embodiment, as shown in FIG. 4, the resin part 32a is provided between the two inlet side oxidant gas communication holes 34a and 34a.

  The arrangement position of the cell-side terminal 47 is not limited to the position shown in FIG. 4, and is between the two outlet-side oxidant gas communication holes 34b and 34b, between the inlet-side fuel gas communication holes 35a and 35a, and the outlet-side fuel gas communication hole. Each resin part 32a between 35b and 35b, between the inlet side or outlet side oxidant gas communication holes 34a and 34b and the outlet side or inlet side fuel gas communication holes 35b and 35a may be used.

The inner peripheral side end portion 47 a of the cell side terminal 47 is in contact with the cathode side outer surface 2 A of the membrane electrode structure 2.
Here, the anode gas seal is a rib-like seal disposed by the anode-side insulating portion 42 and the cathode-side insulating portion 32 so as to surround the electrode surface portions 31A and 41A in the anode-side insulating portion 42 in a double manner. It is established by sandwiching the membrane electrode structure 2 through the inner rib-shaped seal member 51b among the members 51a and 51b, but the seal surface pressure generated by the elastic restoring force of the inner rib-shaped seal member 51b The inner peripheral side end 47a of the cell side terminal 47 provided on the inner surface 32A of the cathode side insulating part 32 is pressed against the membrane electrode structure 2, and the contact between the cell side terminal 47 and the membrane electrode structure 2 is more reliable. It has become a thing.

  On the other hand, the outer peripheral side end portion 47c of the cell side terminal 47, in other words, the portion on the outer side in the surface direction (outer peripheral side) than the seal contact surface 32D where the outer rib-shaped seal member 51a contacts the insulating portion 32a is the cell It is connected to a terminal on the voltage measuring device side (hereinafter referred to as “measurement side terminal 61”).

  As shown in FIG. 2, the measurement side terminal 61 has a main body portion 62 made of, for example, resin and the front surface 62A, that is, the surface facing the stack 5 when connected (in the direction indicated by the white arrow in FIG. 1). A plurality of electrode holding portions 63 and spacer portions 64 projecting in the same manner, and the main body portion 62 and the electrode holding portion 63 are inserted in this order, and the terminal electrode 65 is folded back at the distal end surface of the electrode holding portion 63 in the terminal detachment direction. And is configured.

The electrode holding part 63 and the terminal electrode 65 are inserted into a gap S1 formed between the cathode side separator 3 and the anode side separator 4 constituting one unit cell 1.
Further, the spacer portion 64 is a gap S2 between the unit cells 1, that is, a gap formed between one cathode side separator 3 of the adjacent unit cells 1 and the anode side separator 4 of the other unit cell 1. Inserted.
The spacer section 64 has a trapezoidal shape with a trapezoidal vertical cross section in which the dimension in the fuel cell stacking direction gradually decreases as it goes in the terminal insertion direction.

The terminal electrode 65 is formed into a circular arc shape from a material having elasticity (elasticity), and includes inclined surface portions 65a and 65b on the inlet side when the terminal is inserted and the outlet side when the terminal is detached, and these inclined portions are provided. Between the surface portions 65a and 65b, a bulging portion 65c bulging outward along the fuel cell stacking direction is provided.
The distance t in the fuel cell stacking direction between the outermost surface of the bulging portion 65c and the surface 63A in contact with the insulating portion 42 of the electrode holding portion 63 is the clearance between the cathode-side and anode-side insulating portions 32, 42. It is set to be larger than the dimension T.

When the measurement-side terminal 61 is inserted between the insulating portions 32 and 42 to connect to the cell-side terminal 47, the bulging portion 65c of the terminal electrode 65 is elastically deformed so that the separation dimension t becomes equal to the gap dimension T. In other words, it is inserted into the gap S1 between the opposing insulating portions 32, 42 while being elastically compressed in the gap direction.
Therefore, the terminal electrode 65 presses the outer peripheral side end portion 47c of the cell side terminal 47 by the elastic restoring force in the gap direction, and comes into close contact with the outer peripheral side end portion 47c.

At this time, since the spacer portion 64 is inserted into the gap S2 between the adjacent unit cells 1, warping of the cathode side and anode side insulating portions 32 and 42 that receive elastic restoring force from the terminal electrode 65 is effectively prevented. The
Further, the terminal electrode 65 is smoothly inserted and removed between the insulating portions 32 and 42 without being caught by the inclined surface portions 65a and 65b.

As described above, according to the inter-terminal connection structure according to the present embodiment, the measurement-side terminal 61 is inserted between the cathode-side and anode-side insulating portions 32 and 42, and the terminal electrode 65 is placed on the outer peripheral side of the cell-side terminal 47. By connecting to the end 47c, electrical continuity between the inside and outside of the cell and inside and outside of the stack is ensured, so that the cell voltage from the outside can be maintained without impairing the sealing performance while maintaining the insulation performance from the communication hole portion and the outside. Measurement is possible.
In addition, the reliability of the electrical connection is maintained against disturbances such as vibration and impact that cause the measurement-side terminal to be relatively separated from the stack 5, so that the cell voltage can be measured with high accuracy.

Further, the contact pressure sufficient for measuring the cell voltage can be generated between the cell-side terminal 47 and the membrane electrode structure 2 by the sealing surface pressure by the inner rib-like seal member 51b, so that the contact resistance is lowered and accurate. Measurement is possible.
Furthermore, since the cell side terminal 47 is disposed between the inlet side oxidant gas communication holes 34a and 34a, avoiding the periphery of the inlet side and outlet side cooling water communication holes 36a and 36b, Electric leakage (liquid junction) can be effectively prevented.

The present invention is not limited to the above-described embodiment, and for example, the following configuration can be adopted.
(1) Instead of connecting the measurement side terminal 61 to each unit cell 1 and taking out the cell potential for each unit cell 1, the measurement side terminal 61 may be connected every n cells (n = 1 or more integer). .
(2) Instead of bringing the inner peripheral side end 47a of the cell side terminal 47 into contact with the cathode side outer surface 2A of the membrane electrode structure 2, the anode side outer surface of the membrane electrode structure 2 and the conductive portions 31 of the separators 3 and 4 , 32 may be contacted.

(3) As long as the measurement side terminal 61 can be connected, the outermost peripheral end of the cell side terminal 47 may be positioned on the inner peripheral side of the outer peripheral end surface 32 </ b> B of the insulating portion 32.
(4) The cell side terminal 47 may be provided in the anode side insulating part 31 in place of the cathode side insulating part 32 or together with the cathode side insulating part 32.
(5) Instead of forming the resin part 32a of the cathode-side insulating part 32 in advance and providing the cell-side terminal 47 on the resin part 32a using various surface treatment methods, a metal plate or the like is used when forming the resin part 32a. The cell side terminal 47 may be provided by insert molding.
(6) In the membrane electrode structure 2, the cathode side gas diffusion electrode 22 and the anode side gas diffusion electrode 23 may be the same size.

It is a longitudinal cross-sectional view which shows the connection structure between the terminal by the side of the cell voltage measurement apparatus by one embodiment of this invention, and the terminal by the side of a fuel cell stack. It is an enlarged view of the measurement side terminal shown in FIG. It is a longitudinal cross-sectional view which shows the state before connecting the terminal by the side of the cell voltage measuring apparatus shown in FIG. 1 to the terminal by the side of a fuel cell stack. It is the top view which looked at the cathode side separator shown in FIG. 1 from the inner surface side (electrode surface part side).

Explanation of symbols

1 unit cell (fuel cell)
2 Membrane electrode structure 3 Cathode side separator 4 Anode side separator 5 Stack (fuel cell stack)
21 Solid polymer electrolyte membrane (electrolyte)
22 Cathode side gas diffusion electrode (electrode)
23 Anode side gas diffusion electrode (electrode)
31, 41 Conductive part 31A, 41A Electrode surface part 32, 42 Insulating part 34a Inlet side oxidant gas communication hole (communication hole)
34b Outlet side oxidant gas communication hole (communication hole)
35a Inlet fuel gas communication hole (communication hole)
35b Outlet side fuel gas communication hole (communication hole)
36a Inlet side cooling water communication hole (communication hole)
36b Outlet side cooling water communication hole (communication hole)
47 Cell side terminal (internal / external connection terminal)
47a Inner peripheral side end 47c Outer peripheral side end 61 Measurement side terminal (terminal on the cell voltage measuring device side)
65 terminal electrode

Claims (2)

A fuel cell having a connection structure between a terminal on the cell voltage measuring device side and a terminal on the fuel cell side,
The fuel cell is configured by sandwiching a membrane electrode structure in which electrodes are provided on both sides of an electrolyte by a pair of separators in which a conductive part having an electrode surface part is surrounded by an insulating part, and the pair of separators At least one of the insulating parts is provided with an internal / external connection terminal that extends from the inner peripheral side to the outer peripheral side and has an inner peripheral side end in contact with the membrane electrode structure or the conductive part.
The terminal on the cell voltage measuring device side is inserted between the insulating portions of the pair of separators facing each other in a state of being elastically compressed in the gap direction, and the outer peripheral end of the inner / outer connection terminal is formed by the elastic restoring force. A fuel cell having a connection structure between a terminal on a cell voltage measuring device side and a terminal on a fuel cell side, wherein a terminal electrode to be pressed is provided. The fuel cell having a connection structure between a terminal on the cell voltage measuring device side and a terminal on the fuel cell side according to claim 1, wherein the insulating portion has a communication hole through which a reaction gas or a refrigerant flows.

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