Fuel cell

Abstract

A fuel gas flow field is formed on a surface of a rectangular first metal separator. The fuel gas flow field includes flow grooves extending in the direction of gravity. An outlet buffer is provided at a lower end of the fuel gas flow field. The outlet buffer includes an inclined surface inclined toward a fuel gas discharge passage. The fuel gas discharge passage is positioned below the outlet buffer. Outlet channel grooves are formed by ridges provided between the fuel gas discharge passage and the outlet buffer. Lower ends of the ridges are arranged in a zigzag pattern.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a partial exploded perspective view showing a fuel cell stack according to a first embodiment of the present invention;

FIG. 2 is partial cross sectional view showing the fuel cell stack;

FIG. 3 is an exploded perspective view showing main components of a unit cell of the fuel cell stack;

FIG. 4 is a front view showing a first metal separator of the unit cell;

FIG. 5 is a front view showing a second metal separator of the unit cell;

FIG. 6 is a cross sectional view showing a fuel cell stack according to a second embodiment of the present invention;

FIG. 7 is a partial front view showing a first metal separator of a fuel cell stack according to a third embodiment of the present invention; and

FIG. 8 is a perspective view showing main components of a conventional fuel cell.

Claims

1. A fuel cell formed by stacking a membrane electrode assembly and a separator in a horizontal stacking direction, said membrane electrode assembly including a pair of electrodes and an electrolyte membrane interposed between said electrodes, said separator having a rectangular shape including long sides extending in the direction of gravity and short sides extending horizontally in a direction perpendicular to the stacking direction, said separator having a reactant gas flow field for supplying one of reactant gases along an electrode surface in the direction of gravity, wherein said reactant gas flow field includes an inlet buffer at an upper position and an outlet buffer at a lower position;a reactant gas supply passage for supplying the one of reactant gases to said reactant gas flow field and a reactant gas discharge passage for discharging the one of reactant gases from the reactant gas flow field extend through said separator in the stacking direction; andsaid reactant gas discharge passage is positioned below said outlet buffer, and at least said outlet buffer is inclined toward said reactant gas discharge passage.

2. A fuel cell according to claim 1, wherein said reactant gas supply passage is positioned above said inlet buffer.

3. A fuel cell according to claim 1, wherein said reactant gas flow field comprises a plurality of wavy flow grooves; and a coolant flow field is provided for supplying a coolant horizontally to cool the electrode surface.

4. A fuel cell according to claim 1, wherein a plurality of outlet channel grooves are formed by ridges between said outlet buffer and said reactant gas discharge passage; and lower ends of said ridges are arranged in a zigzag pattern.

5. A fuel cell according to claim 4, wherein the lower end of said ridge has a curved end surface.

6. A fuel cell according to claim 3, wherein said coolant flow field is sandwiched between a plurality of said membrane electrode assemblies.

7. A fuel cell according to claim 3, wherein said reactant gas flow field comprises a plurality of wavy flow grooves and a plurality of wavy ridges; and lower ends of said wavy ridges are arranged in a zigzag pattern.

8. A fuel cell according to claim 7, wherein the lower end of said wavy ridge has a curved end surface.