KR100728792B1 - Fuel cell system and stack - Google Patents

Abstract

The present invention provides at least one by means of a membrane-electrode assembly (MEA) and a separator disposed on both sides of the membrane-electrode assembly so as to increase the strength by improving the structure of the end plate for supporting and fixing a plurality of stacked cells on both sides. And an end plate disposed at the outermost part of the electricity generating unit and an end plate having protruding ribs protruding from a front surface thereof, wherein the end plate has a plurality of fastening holes penetrating through the front surface thereof, and the reinforcing ribs have the fastening holes. Provided is a stack for a fuel cell system spaced apart from and formed in an area that does not interfere with a fastening hole.

Stack, End Plate, Reinforcement Rib, Fastening Hole

Description

FUEL CELL SYSTEM AND STACK

1 is a schematic diagram showing an overall configuration of a fuel cell system according to an embodiment of the present invention.

2 is an exploded perspective view showing the configuration of a stack according to an embodiment of the present invention.

3 is a schematic front view illustrating some components of a stack according to an embodiment of the present invention.

4 is a schematic front view showing some components of a stack according to another embodiment of the present invention.

The present invention relates to a fuel cell system, and more particularly, to a fuel cell system capable of improving strength by improving an end plate structure of a stack.

As is known, a fuel cell is a power generation system that directly converts the chemical reaction energy of hydrogen contained in a hydrocarbon-based material such as methanol and oxygen or air containing oxygen into electrical energy.

The fuel cell uses hydrogen produced by reforming methanol or ethanol as a fuel, and has a wide range of applications such as mobile power sources such as automobiles, distributed power sources such as houses and public buildings, and small power sources such as electronic devices. Have

The fuel cell is a membrane-electrode assembly (MEA) that generates electricity through an oxidation / reduction reaction of hydrogen and oxygen, and closely adheres to both sides of the membrane-electrode assembly to supply hydrogen and oxygen to the membrane-electrode assembly. A unit cell is formed by a separator (also called a bipolar plate), and a plurality of cells of such a unit are stacked to form a stack.

The stack is in close contact with a separate pressure plate made of metal to the outermost separator, and the stack is assembled by tightening the pressure plate with a threaded fastening bar and a nut while a current collector plate is interposed between the outermost separator and the pressure plate. It consists of one structure.

However, the conventional fuel cell system has a problem in that the pressure plate is deformed by the stress applied to the pressure plate as both pressure plates are tightened by the nut in the process of fastening the pressure plate with the fastening rod and the nut for stack assembly. have.

This is because the pressing plate is not able to withstand the stress as the nut is tightened and is bent, so that the airtightness of each cell stacked between the pressing plates is not maintained due to the deformation of the pressing plate, thereby degrading the performance of the battery or shortening its lifespan. Problems arise.

In particular, in the case of a stack consisting of a pressure plate having a thickness of 2 mm or less, the deformation of the pressure plate is further increased, thereby making the above problem more serious.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object thereof is to provide a fuel cell system and a stack capable of increasing strength by improving the structure of an end plate for supporting and fixing a plurality of stacked cells on both sides. It is.

In order to achieve the above object, the present invention has a structure in which a rib is formed in the end plate.

The stack for a fuel cell system of the present invention includes at least one electricity generating portion by a membrane-electrode assembly (MEA) and separators disposed on both sides of the membrane-electrode assembly, and is disposed at the outermost portion of the electricity generating portion and reinforced on the front surface. And an end plate having integrally formed ribs.

In addition, the present invention includes a fastening portion for tightening the end plate and fastening the electricity generating portion.

The fastening part includes a plurality of fastening rods passing through the outermost end plates; And a nut screwed to both ends of the fastening rod.

In this case, the reinforcing rib may be formed along an edge of each side of the end plate.

In addition, the reinforcing rib may be formed in a diagonal direction of the end plate.

In the stack for a fuel cell system according to the present invention, the fastening rod may have a structure that penetrates the end plate and the entire electricity generating unit.

In addition, in the stack for a fuel cell system according to the present invention, the fastening portion may have a structure that penetrates both end plates positioned at the outermost portion of the electricity generating portion.

In addition, in the stack for a fuel cell system according to the present invention, an insulating layer may be formed on a surface of the fastening rod.

In addition, the fuel cell system according to the present invention to achieve the above object, the stack for generating electrical energy through the electrochemical reaction of hydrogen and oxygen; A fuel supply for supplying a fuel containing hydrogen to the stack; And an oxygen source for supplying oxygen to the stack,

The stack includes at least one electricity generation unit by a membrane-electrode assembly (MEA) and separators disposed on both sides of the membrane-electrode assembly, and a reinforcement rib is integrally formed on an outermost side of the electricity generation unit. And end plates.

In the fuel cell system according to the present invention, a plurality of battery generators may be provided to form the stack having a stacked structure by the plurality of electricity generators.

In a fuel cell system according to the invention, the fuel supply source comprises: a fuel tank for storing fuel containing hydrogen; And a fuel pump connected to the fuel tank.

In the fuel cell system according to the present invention, the fuel supply source is connected to the electricity generation unit and the fuel tank to receive the fuel from the fuel tank to generate hydrogen gas, and supply the hydrogen gas to the electricity generation unit. It may also include a reformer.

In addition, in the fuel cell system according to the present invention, the oxygen supply source may include an air pump for sucking air and supplying the air to the electricity generator.

In the fuel cell system according to the present invention, the separator is disposed in close contact with one surface of the membrane electrode assembly to form a hydrogen passage for supplying hydrogen gas to the membrane electrode assembly, and the other surface of the membrane electrode assembly. It can be arranged in close contact with the air electrode to supply air to the membrane-electrode assembly.

In the fuel cell system according to the present invention, both the separators are made of a metal material, and the above-described passages can be formed by pressing the plate-shaped metal.

In addition, in the fuel cell system according to the present invention, the stack may include a fastening part for fastening the end plate to fasten the electricity generating part.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art may easily implement the present invention. As those skilled in the art would realize, the described embodiments may be modified in various different ways, all without departing from the spirit or scope of the present invention.

1 is a schematic diagram showing an overall configuration of a fuel cell system according to an embodiment of the present invention.

Referring to this drawing, the fuel cell system 100 according to the present invention is described. The fuel cell system 100 reforms a fuel containing hydrogen to generate hydrogen gas, and generates the hydrogen gas and the oxidant gas. A polymer electrolyte fuel cell (PEMFC) method that chemically reacts to generate electrical energy is employed.

In the fuel cell system 100, a fuel for generating electricity generally refers to hydrogen gas generated by reforming of the fuel, in addition to a fuel in a liquid or gaseous state such as methanol, ethanol or natural gas. However, the fuel described in the present embodiment means the fuel of electrons made of a liquid phase for convenience.

The system 100 may use oxygen gas stored in a separate storage means as an oxidant gas that reacts with hydrogen gas, and may use air containing oxygen. However, the latter example is explained below.

The fuel cell system 100 basically includes a stack 10 that generates electrical energy through an electrochemical reaction between hydrogen and oxygen, and generates hydrogen gas from the fuel and transfers the hydrogen gas to the stack 10. A fuel supply source 30 for supplying and an oxygen supply source 40 for supplying air to the stack 10.

The stack 10 is connected to a fuel supply source 30 and an oxygen supply source 40 to receive the hydrogen gas from the fuel supply source 30 and to receive air from the oxygen supply source 40. The fuel cell is configured to generate electrical energy by reacting oxygen electrochemically.

The fuel supply source 30 includes a fuel tank 31 for storing fuel, a fuel pump 33 for discharging the fuel stored in the fuel tank 31, and a fuel supplied from the fuel tank 31 for receiving hydrogen from the fuel. A reformer 35 for generating gas and supplying the hydrogen gas to the stack 10.

The oxygen source 40 includes an air pump 41 that sucks air with a predetermined pumping force and supplies this air to the stack 10.

Reformer 35 in the fuel source 30 has a conventional reformer structure that generates hydrogen gas from the fuel through a chemical catalytic reaction by thermal energy and reduces the concentration of carbon monoxide contained in the hydrogen gas. In detail, the reformer 35 generates hydrogen gas from the fuel through catalytic reaction such as steam reforming, partial oxidation, or autothermal reaction. As an example, the reformer 35 reduces the concentration of carbon monoxide contained in the hydrogen gas by a method such as a catalytic reaction such as a water gas conversion method, a selective oxidation method, or purification of hydrogen using a separator.

As an alternative, the fuel cell system 100 according to the present invention is a direct methanol fuel cell (DMFC) system capable of producing electricity by directly supplying the fuel of the above-described arrangement to the stack 10. May be employed. This direct methanol fuel cell, unlike the polymer electrolyte fuel cell described above, does not require the reformer 35 shown in FIG.

Hereinafter, the fuel cell system 100 to which the polymer electrolyte fuel cell method is applied will be described as an example. However, the present invention is not necessarily limited thereto.

Stack 10 of the hydrogen gas generated through the reformer 35 of the fuel supply source 30 and the air sucked by the air pump 41 during the operation of the fuel cell system 100 according to the present invention configured as described above When supplied to, the stack 10 generates electrical energy through the electrochemical reaction of the hydrogen gas and oxygen contained in the air.

In the present invention will be described in detail with reference to the accompanying drawings an embodiment constituting the stack 10 as follows.

2 is an exploded perspective view showing a configuration of a stack according to an embodiment of the present invention, Figure 3 is a schematic front view showing a part of the stack according to an embodiment of the present invention.

2 to 3, the stack 10 applied to the present system 100 is centered on a membrane-electrode assembly (MEA) (hereinafter referred to as 'MEA') 12. And a separator (also referred to as 'bipolar plate' in the art) 13 on both sides thereof, and includes an electricity generating unit 11 of a minimum unit for generating electricity. Therefore, the stack 10 of the laminated structure according to the present exemplary embodiment may be formed by sequentially stacking the plurality of electricity generating units 11 as described above.

The MEA 12 interposed between the separators 13 has an anode electrode and a cathode electrode (not shown) disposed on both surfaces thereof, and an electrolyte membrane (not shown) is provided between the two electrodes. . The anode electrode functions to oxidize hydrogen gas supplied through the separator 13 to convert hydrogen into hydrogen ions (protons) and electrons. The cathode electrode functions to reduce and react the oxygen in the air supplied through the separator 13 with the hydrogen ions and electrons moved from the anode electrode to generate heat and moisture at a predetermined temperature. The electrolyte membrane is formed of a solid polymer electrolyte having a thickness of 50 to 200 µm, and functions as an ion exchange to move hydrogen ions generated at the anode electrode to the cathode electrode.

The separators 13 are arranged to be in close contact with each other with the MEA 12 interposed therebetween, and form a hydrogen passage and an air passage at a close contact with the MEA 12. The hydrogen passage is located on the anode electrode side of the MEA 12 and serves to supply hydrogen gas supplied from the reformer 35 to the anode electrode. And the air passage is located on the cathode electrode side of the MEA (12) serves to supply oxygen in the air supplied from the air pump 41 to the cathode electrode. In addition, the separator 13 also functions as a conductor that connects the anode electrode and the cathode electrode in series.

Preferably, as described above, the separator 13 forms a hydrogen passage on one surface of the separator 13 and an air passage on the other surface of the separator 13. Alternatively, each hydrogen passage and air passage may be formed only on one surface of the separator 13 located on both sides of the MEA 12. The separator 13 may be formed of graphite or carbon composite to form the hydrogen passage and the air passage. Alternatively, the separator 13 may be formed by pressing a metal plate to form the hydrogen passage and the air passage. have.

The separator 13 omits a specific configuration of how hydrogen gas and air are supplied and circulated with respect to the hydrogen passage and the air passage in the drawing, but the configuration of the separator 13 includes the hydrogen gas and the air as the hydrogen passage and the air passage. A conventional method of supplying and circulating and releasing unreacted hydrogen gas and air remaining after reacting at the anode electrode and the cathode electrode of the MEA 12 may be applied.

During operation of the fuel cell system 100 according to the present embodiment configured as described above, hydrogen gas is supplied to the anode electrode of the MEA 12 through the separator 13, while air containing oxygen is supplied to the cathode electrode. do. Therefore, the hydrogen electrode separates the hydrogen gas into electrons and hydrogen ions (protons). In this case, the hydrogen ions are moved to the cathode electrode through the electrolyte membrane of the MEA 12, and electrons are not moved through the electrolyte membrane but move to the cathode electrode of the neighboring MEA 12 through the separator 13. When a current is generated by the flow of electrons, heat and moisture are generated at the cathode electrode through a coupling reaction between the transferred hydrogen ions and electrons and the oxygen.

Meanwhile, in the present embodiment, the end plates 15a and 15b for stacking and fixing a plurality of electricity generating units are disposed at the outermost side of the stack 10.

The end plates 15a and 15b may be configured as current collecting units for collecting electrical energy generated by the electricity generating unit 11.

In the present embodiment, the end plates 15a and 15b are formed to have a larger area than the separators 13 positioned therebetween. That is, the end plate has a structure in which the edge portion thereof extends outside the edge end of the separator 13 positioned between them, and a fastening portion is installed through a portion extending outside the separator 13 so that both end plates 15a are provided. , 15b) to be combined.

The fastening unit 19 is configured to press the plurality of electric generators 11 to a certain pressure and fasten them in order to prevent leakage of hydrogen gas and air supplied to the electric generator 11 and to have a structure as a battery. Fastening rods 19a which are respectively installed through the plurality of fastening holes 19c formed in the clearance portions A of the end plates 15a and 15b, and fastened to the screw portions formed at both ends of the fastening rods 19a. And a nut 19b to fix the end plates 15a and 15b.

Therefore, by fastening the nuts 19b to both ends of the fastening rods 19a penetrating the fastening holes 19c, the end plates 15a and 15b of both sides are pressed to appropriately press the stack 10 according to the present embodiment. Will be able to fasten fastening.

The end plates 15a and 15b have a structure in which reinforcing ribs 17 are formed along the edge of the outer surface.

The rib 17 is formed to protrude outward with respect to the front surfaces of the end plates 15a and 15b and is not particularly limited in terms of its formation height and thickness.

In addition, the ribs 17 are arranged in a straight line along the edge of the surface between the fastening holes 19c formed at each corner of the rectangular end plates 15a and 15b, and the length of the ribs 17 is equal to the amount of the ribs 17. It is sufficient that the end extends to such an extent that it does not interfere with the nut 19b abutting around the fastening hole 19c.

In addition, the rib 17 may be formed in a rectangular cross-sectional shape, but is not limited thereto, and may be applied in various forms such as an arc-shaped cross-sectional shape.

As described above, the rib 17 is integrally protruded from the end plates 15a and 15b so that the nut 19b is fastened to the fastening rod 19a so that both end plates 15a and 15b are interposed between the electric generators. When tightening the stress is applied to the end plate at this time the rib 17 formed in the end plate is to increase the strength of the end plate to prevent deformation of the end plate to the maximum.

On the other hand, Figure 4 is a view showing another embodiment of the end plate, according to the above-described reinforcing rib 18 is formed integrally protruding on the outer surface of the end plate (15a, 15b), the rib 18 has a structure formed diagonally at the edges of the end plates 15a and 15b.

The rib 18 is formed to protrude outward with respect to the front surfaces of the end plates 15a and 15b, and is not particularly limited in terms of forming height and thickness thereof.

In addition, the ribs 18 are disposed in a straight line between the fastening holes 19c formed at the corners of the rectangular end plates 15a and 15b and the fastening holes 19c in the diagonal direction, and the length of the ribs 18 is rib 17. It is sufficient if both ends of the e) extend to such an extent that they do not interfere with the nut 19b which is in contact with the fastening hole 19c.

In addition, the rib 18 is formed in a rectangular cross-sectional shape, but is not limited thereto, and can be applied in various forms such as an arc-shaped cross-sectional shape.

Although the preferred embodiments of the present invention have been described above, the present invention is not limited thereto, and various modifications and changes can be made within the scope of the claims and the detailed description of the invention and the accompanying drawings. Naturally, it belongs to the scope of the invention.

As described above, according to the fuel cell system according to the present invention, it is possible to prevent stress concentration of the nut against the end plate and to prevent excessive deformation of the end plate, the fastening rod, and the nut.

Claims (20)

At least one electricity generating unit by a membrane-electrode assembly (MEA) and separators disposed on both sides of the membrane-electrode assembly; An end plate disposed at the outermost part of the electricity generating unit and having a reinforcing rib protruding from a front surface thereof, The end plate has a plurality of fastening holes penetratingly formed on a front surface thereof, and the reinforcing ribs are formed in a region which is spaced apart from the fastening holes and does not interfere with the fastening holes. The fuel cell system stack of claim 1, further comprising a plurality of fastening rods penetrating through the fastening holes of the end plate, and nuts coupled to both ends of the fastening rods to fasten the electric generator by tightening both end plates. The stack of claim 1, wherein the reinforcing ribs are formed along edges of each side of the end plate. The stack of claim 1, wherein the reinforcing rib is formed on an outer surface of the end plate. The stack of claim 1 wherein the reinforcing ribs are straight. The stack of claim 1, wherein the ribs have a rectangular cross section. The stack of claim 1, wherein the reinforcing ribs are formed in a diagonal direction of the end plate. The stack of claim 1, wherein the fastening rods penetrate the entire electricity generating unit. The stack for a fuel cell system as claimed in claim 1, wherein the fastening rod passes through both separators located at the outermost portion of the electricity generating unit. A stack for generating electrical energy through an electrochemical reaction of hydrogen and oxygen; A fuel supply for supplying a fuel containing hydrogen to the stack; And An oxygen source supplying oxygen to the stack Including; The stack is, At least one electricity generation unit by a membrane-electrode assembly (MEA) and separators disposed on both sides of the membrane-electrode assembly, and a plurality of fastening holes disposed in the outermost side of the electricity generation unit and penetrating through the front surface thereof, And an end plate spaced apart from the fastening hole and having a reinforcing rib protruding from an area which does not interfere with the fastening hole. The method of claim 10, And a plurality of electricity generating units, and forming the stack of a stacked structure by the plurality of electricity generating units. The method of claim 10, The fuel source is: A fuel tank for storing fuel containing hydrogen; And A fuel cell system comprising a fuel pump connected to the fuel tank. The method of claim 12, The fuel supply system includes a reformer connected to the electricity generating unit and the fuel tank, receiving a fuel from the fuel tank to generate hydrogen gas, and supplying the hydrogen gas to the electricity generating unit. The method of claim 10, And the oxygen source includes an air pump that sucks air and supplies the air to the electricity generator. The method of claim 10, The separator is disposed in close contact with one surface of the membrane-electrode assembly to form a hydrogen passage for supplying hydrogen gas to the membrane-electrode assembly, and the separator is disposed in close contact with the other surface of the membrane-electrode assembly. A fuel cell system forming an air passage for supplying the gas. The fuel cell system of claim 10, wherein the reinforcing rib is formed along an edge of each side of the end plate. The fuel cell system of claim 10, wherein the reinforcing rib is formed on an outer surface of the end plate. The fuel cell system of claim 10, wherein the reinforcing rib is straight. The fuel cell system of claim 10, wherein the rib has a rectangular cross-sectional shape. The fuel cell system of claim 10, wherein the reinforcing rib is formed in a diagonal direction of the end plate.

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