KR100982327B1 - Stack for fuel cell and fuel cell system - Google Patents

Abstract

The present invention includes an electrode-electrolyte assembly (MEA) and a bipolar plate disposed on the side of the electrode-electrolyte composite so as to simplify the stack fastening structure so as to be excellent in disassembly and assembly. At least one electricity generating unit; At least one fastening band wound to the outside of the electricity generation unit; It is provided at the tip of the band to provide a fuel cell stack comprising a tightening means for tightening and releasing the band to fasten and secure the electrical generation unit.

Band, fastener, worm, helix

Description

Stack for fuel cell and fuel cell system having this stack {STACK FOR FUEL CELL AND FUEL CELL SYSTEM}

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 for a fuel cell according to an embodiment of the present invention;

3 is a perspective view showing a combined state of a stack for a fuel cell according to an embodiment of the present invention;

4 is an exploded perspective view illustrating a part of a stack for a fuel cell according to an embodiment of the present invention;

5 is a cross-sectional view for explaining a fastening action of a stack for a fuel cell according to an embodiment of the present invention;

6 and 7 is a partially cut perspective view showing a stack according to another embodiment of the present invention,

Figure 8 is a side view showing a stack fastening structure for a fuel cell according to the prior art.

The present invention relates to a fuel cell, and more particularly, to a stack for a fuel cell and a fuel cell system that are easy to fasten and disassemble stack unit cells constituting a fuel cell.

In general, a fuel cell is a power generation that directly converts chemical energy into electrical energy by an electrochemical reaction caused by hydrogen contained in a hydrocarbon-based material such as methanol, ethanol or natural gas and oxygen in air as a fuel. The system is characterized by the simultaneous use of electricity generated by the electrochemical reaction of fuel gas and oxidant gas and heat by-products thereof without the combustion process.

A fuel cell system using a polymer electrolyte fuel cell (PEMFC), which has been recently developed, is basically a fuel cell body (hereinafter referred to as a stack for convenience), a fuel tank, And a fuel pump for supplying fuel from the fuel tank to the stack, wherein the fuel is reformed in the process of supplying the fuel stored in the fuel tank to the stack to generate hydrogen gas and supply the hydrogen gas to the stack. It may include a reformer. Therefore, the polymer electrolyte fuel cell supplies the fuel stored in the fuel tank to the reformer by the pumping force of the fuel pump, the reformer reforms the fuel to generate hydrogen gas, and the stack electrochemically reacts the hydrogen gas with oxygen. Electric energy is produced.

In the fuel cell system as described above, a stack that substantially generates electricity includes an electrode-electrolyte composite having an anode electrode and a cathode electrode attached thereto with an electrolyte membrane interposed therebetween to oxidize / reduce hydrogen gas and air. MEA) and a unit cell including a bipolar plate disposed on both sides of the electrode-electrolyte composite for supplying hydrogen gas and air to the electrode-electrolyte composite are configured by successive stacking. In this case, the bipolar plates located at the outermost sides of the stack are defined as end plates.

The stack of the above structure must fasten and fix a plurality of stacked cells to prevent fuel leakage and to have a structure as a battery. To this end, each component is bonded together using an adhesive or through the end plate. A method of pressing cells at a constant pressure is used.

The pressurized fastening structure using the end plate is shown in FIG. 8. The fuel cell stack fastening structure according to the related art shown in FIG. 8 includes two end plates 210 supporting both ends of the fuel cell stack 200. The fastening rod 220 penetrating the hole formed in the) and the nut 230 is fastened to the male screw formed on the end of the fastening rod 220 and fixed to the end plate.

Therefore, by fastening the nuts formed with female threads to the male threads formed at both ends of the fastening rods penetrating the holes, respectively, it is possible to fasten and fix the stack by pressing both end plates.

However, the above-described conventional structure causes a lot of parts such as bolts, nuts, washers, etc., resulting in an increase in cost, and there is a problem in that a lot of time is required for assembly work and disassembly work.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems, and has an object of the present invention to provide a fuel cell stack and a fuel cell system excellent in disassembly and assembly by simplifying a stack fastening structure.

In order to achieve the above object, the present invention has the gist of the at least one electricity generating unit forming a stack is fastened and fastened by a band.

To this end, the fuel cell stack of the present invention includes at least one electricity generating unit including an electrode-electrolyte assembly (MEA) and a bipolar plate disposed on a side of the electrode-electrolyte composite. The fastening band is wound to the outside of the electric generator and the band is tightened by a fastening means installed at the tip of the band to fasten and fix the electric generator.

The band is not particularly limited in size of its width, and one or two or more bands may be provided for the stack.

In addition, when two or more bands are installed, the bands may be installed in parallel with each other at regular intervals or may be alternately installed in a cross shape.

Here, the band is made of a non-conductor, preferably made of a material with less thermal deformation.                     

Meanwhile, the fuel cell system according to the present invention includes at least one electricity generation unit including an electrode-electrolyte assembly (MEA) and a bipolar plate disposed on a side of the electrode-electrolyte composite. A stack including a fastening band wound to the outside of the electricity generation unit, and fastening means installed at a tip of the band to tighten the band; A fuel supply unit supplying fuel to the stack; It includes a cooling device for circulating the cooling medium to the stack to cool the heat generated in the stack.

The fuel cell system may further include a reformer configured to generate hydrogen gas by reforming the fuel supplied from the fuel supply unit.

In addition, the fuel cell system according to the present invention may be made of a polymer electrolyte fuel cell (PEMFC) method.

In addition, the fuel cell system according to the present invention may be made of a direct methanol fuel cell (DMFC) method.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

First, the present system will be described with reference to FIG. 1.

According to the above drawings, the present system 100 is basically a reformer 20 for reforming a liquid fuel to generate hydrogen gas, and the chemical reaction of the hydrogen gas generated by the reformer 20 with external air. The stack 10 converts energy into electrical energy to produce electricity, the fuel supply unit 30 supplying the liquid fuel to the reformer 20, and the air for generating electricity to the stack 10. It comprises an air supply unit 40 and a cooling device 70 for cooling the stack.

Of course, the direct methanol fuel cell (DMFC) method has a structure in which the reformer is excluded. Hereinafter, a fuel cell system employing a polymer electrolyte fuel cell method will be described as an example, and the present invention is not necessarily limited thereto.

The reformer 20 is a device that not only converts a liquid fuel into hydrogen gas for generating electricity of the stack 10 by the reforming reaction, but also reduces the concentration of carbon monoxide contained in the hydrogen gas. Typically, the reformer 20 includes a reforming unit for reforming a liquid fuel to generate hydrogen gas, and a carbon monoxide reduction unit for reducing the concentration of carbon monoxide from the hydrogen gas. The reforming unit converts the fuel into hydrogen-rich reforming gas through catalytic reactions such as steam reforming, partial oxidation or autothermal reaction. The carbon monoxide reducing unit reduces the concentration of carbon monoxide from the reformed 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.

The fuel supply unit 30 is connected to the reformer 20, and includes a fuel tank 31 for storing liquid fuel and a fuel pump 33 connected to the fuel tank 31. The fuel pump 33 has a function of discharging the liquid fuel stored in the fuel tank 31 from the inside of the tank by a predetermined pumping force. At this time, the fuel supply unit 30 and the reformer 20 may be connected by the first supply line 91.

The air supply unit 40 is installed to be connected to the stack 10 and includes an air pump 41 that can suck external air with a predetermined pumping force and supply the external air to the stack 10. In this case, the stack 10 and the air supply unit 40 may be connected and installed by the third supply line 93.

On the other hand, Figure 2 is an exploded perspective view showing the configuration of a fuel cell stack according to an embodiment of the present invention, Figure 3 is a perspective view showing a combined state of the fuel cell stack according to an embodiment of the present invention, Figure 4 is 5 is an exploded perspective view illustrating a part of a stack for a fuel cell according to an exemplary embodiment of the present invention, and FIG. 5 is a cross-sectional view illustrating a fastening operation of the stack for a fuel cell according to the exemplary embodiment of the present invention.

Referring to the drawings, the stack 10 applied to the system 100 receives a plurality of reformed hydrogen gas and external air through the reformer 20 and induces oxidation / reduction reactions thereof to generate electrical energy. And an electricity generating unit.

Each of the electricity generating units refers to a cell of a unit for generating electricity.

The electricity generating unit is an electrode-electrolyte assembly (MEA) 11 for oxidizing / reducing hydrogen gas and air, and a bipolar plate for supplying hydrogen gas and air to the electrode-electrolyte composite ( 12). The electricity generating unit has the electrode-electrolyte composite 11 in the center and bipolar plates 12 are disposed on both sides thereof. As a result, the stack 10 is configured by continuously arranging a plurality of electricity generating units as described above. In this case, the bipolar plates positioned at the outermost sides of the stack 10 are defined as end plates 13.                     

In this fuel cell, a fastening band 14 is wound around the outer side of the electrical generation part forming the stacked stack, and the fastening band 14 is tightened by a fastening means installed at the tip of the band 14, so that the electric generation part is subjected to a constant pressure. Fastening and fixing.

The tightening means connects the band 14 and tightens or loosens the band 14 with respect to the electricity generating unit. As shown in FIG. 4, the bracket 15 is installed at one end of the band 14. ) And a cover (16) covering the bracket (15), a worm (17) rotatably installed in the longitudinal direction of the band (14) inside the cover (16), the bracket (15) and the worm (17). Spiral hole 18 is formed at the other end of the band (14) to enter between and engaged with the worm (17).

Accordingly, as shown in FIG. 5, when the worm 17 is rotated, the free end of the band 14 that is held by the spiral hole 18 in the worm 17 is moved relative to the bracket 15 to stack the worm 17. Tighten or release the (10).

That is, the bracket 14 installed on the band 14 is positioned on the outermost end plate 13 of the electrical generation unit constituting the stack, and the band 14 is freely wound while the band 14 is wrapped around the stack 10. When the stage enters the space between the bracket 15 and the worm 17 and the worm 17 is rotated in one direction by using a jig, the worm 17 is rotated and the screw formed on the worm 17 has a band 14 The band 14 is moved with respect to the worm 17 fixed to the bracket 15 while being engaged with the spiral hole 18 formed in the).

Accordingly, the free end of the band 14 continues to move past the bracket 15, and consequently, the band 14 is tightened with respect to the electric generator to fasten and fix the electric generator.

In this case, the band 14 is tensioned by itself and has a property to be released, but the screw formed in the worm 17 is engaged with the spiral hole 18 formed in the band 14 due to the characteristics of the worm 17. The fastening state is maintained as it is.

Here, the worm 17 is rotatably mounted between the bracket 15 and the cover 16, and a projection or a jig such as a wrench or a screw is fastened to one side of the worm 17 so as to easily rotate the worm 17. Dates or crosses are formed. For example, FIG. 3 illustrates well that a cross groove 19 is formed at the tip of the worm 17 so that a Phillips screwdriver can be used to tighten and loosen the band 14.

Considering that the fastening band 14 is in contact with each of the electricity generating units constituting the stack, the material is made of a non-conductor so as not to electrically conduct each bipolar plate, so that thermal deformation is low and the stack fastening pressure can be continuously maintained. Material is used, preferably mild steel or alloy steel or light alloy steel coated with an insulating material on the surface may be used. The mild steel refers to steel having a carbon content of about 0.2%, and the alloy steel mainly uses a metal having a high content of chromium and nickel as heat-resistant alloy steel, and is applicable to chromium steel and stainless steel with high corrosion resistance, and to reduce weight. Light alloy steel such as aluminum or magnesium alloy steel may be used.

In addition, the spiral hole 18 is not required to be formed over the entire band 14, it is preferable to form only the length necessary for fastening at the free end.

6 and 7 illustrate another embodiment of the present invention. According to the above drawings, two bands 14 which tighten and fasten the electricity generation unit are provided in parallel to each other at a predetermined interval. It is.

In addition, the two bands 14 which are fastened to the electricity generation unit may be fastened in a cross shape, respectively, fastened at different sides.

In the case of the above structure, it is possible to disperse the fastening pressure applied to the band 14 and to provide an advantage of increasing the fastening force of the electric generator.

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 present invention, a simple structure can reduce the number of parts required for stack assembly such as bolts and nuts, thereby reducing the cost.

In addition, by reducing the size of the end plate it is possible to minimize the size of the stack.

In addition, it is possible to increase the yield by reducing the stack assembly process.

In addition, the stack assembly and disassembly is easy to reduce the time and effort required to remove the stack during repair.

Claims (9)

At least one electricity generation unit including an electrode-electrolyte assembly (MEA) and a bipolar plate disposed on a side of the electrode-electrolyte composite; At least one fastening band wound to the outside of the electricity generation unit; It is installed at the tip of the band includes a tightening means for tightening and releasing the band to fasten and secure the electrical generation unit,  The tightening means includes a bracket installed at one end of the band, a cover covering the bracket, a worm placed rotatably in the longitudinal direction of the band inside the cover, and the other end of the band entering between the bracket and the worm. A stack for a fuel cell comprising a spiral hole formed in and engaged with the worm. The method of claim 1, The band is a fuel cell stack is installed in parallel with a predetermined interval to the stack. The method of claim 1, And the bands are alternately installed crosswise with respect to the stack. delete 4. The method according to any one of claims 1 to 3, The band is a fuel cell stack selected from the group of mild steel, alloy steel or light alloy steel coated with an insulating material on the surface. At least one electricity generating unit including an electrode-electrolyte assembly (MEA), a bipolar plate disposed on a side of the electrode-electrolyte composite, and a winding wound outward of the electricity generating unit A stack including a band and fastening means installed at a tip of the band to tighten or loosen the band; A fuel supply unit supplying fuel to the stack; An air supply unit for supplying air to the stack, The tightening means includes a bracket installed at one end of the band, a cover covering the bracket, a worm placed rotatably in the longitudinal direction of the band inside the cover, and the other end of the band entering between the bracket and the worm. And a spiral hole formed in and engaged with the worm. 7. The fuel cell system according to claim 6, further comprising a reformer for reforming the fuel supplied from the fuel supply unit to generate hydrogen gas between the stack and the fuel supply unit. The method of claim 7, wherein The fuel cell system is a fuel cell system comprising a polymer electrolyte fuel cell (PEMFC) method. The method of claim 6, The fuel cell system is a fuel cell system comprising a direct methanol fuel cell (DMFC) system.

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