Patent Application
20090181284
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1. Field of the Invention
The present invention relates generally to a fuel cell, and more particularly to an innovative fuel cell with a sealing structure for the coupling portion of the bipolar plate.
2. Description of Related Art
Including Information Disclosed Under 37 CFR 1.97 and 37 CFR 1.98.
As far as a common fuel cell is concerned, the bipolar plate is a structure arranged at both sides of the membrane electrode assembly (MEA). The bipolar plate is made of materials featuring high conductibility and workability, such as graphite, aluminum and stainless steel. The coupling surface of the bipolar plate is provided with a flow channel for guiding fuel and allowing preset reacting gas (e.g. hydrogen and oxygen) to reach a gas diffusion layer arranged between the bipolar plates and to enter into a catalyst layer, generating current through a chemical conversion reaction. The bipolar plate can also conduct current externally to a preset circuit.
However, the bipolar plate is solidly coupled to the gas diffusion layer, so the coupling surface must be processed precisely to ensure the intended air-tightness, leading to much higher processing costs, greater risk for defects, and poorer economic efficiency. Even if the coupling surface reaches the intended precision, the local stress generated by the pressure points of fittings (e.g. bolts and rivets) may lead to warping and deformation of the coupling surface when a plurality of bipolar plates and gas diffusion layers are overlapped and fastened. So, the solid coupling surface of the bipolar plate and gas diffusion layer may yield a gap or clearance notwithstanding the slight deformation. The flow channel for the bipolar plate is separated depending upon different properties of preset fuels gases (e.g hydrogen and oxygen), so the gases can flow along the preset channel to generate the correct electrochemical reaction. Thus, air-tightness of the coupling surface is a crucial element to the separation of flow channels of different gases. As mentioned above, when the coupling surface generates a clearance, the gases of different properties will be mixed before reaching the gas diffusion layer, possibly leading to a negative influence on the generating efficiency of fuel cells or even an explosion hazard due to the contact reaction of excess fuels with different properties. So, this is an important issue to be addressed for the sealing structure of a bipolar plate of a fuel cell.
For this reason, a gasket is developed to be located between the coupling surfaces of the bipolar plate and gas diffusion layer for the desirable air-tightness. When the gasket is assembled onto the bipolar plate and gas diffusion layer, the gasket made of soft material will yield to deformation under pressure. An optimum air-tightness effect could be achieved if the deformation is controlled to an exact preset value. But, owing to the lack of measures for accurately controlling the pressure state of the gasket, the gasket will be prone to quick degradation and hardening, resulting in a shorter service life.
Thus, to overcome the aforementioned problems of the prior art, it would be an advancement in the art to provide an improved structure that can significantly improve efficacy.
Therefore, the inventor has provided the present invention of practicability after deliberate design and evaluation based on years of experience in the production, development and design of related products.
Based on the unique concave surface, when the bipolar plate, gas guidance and reaction layer and gasket of the fuel cell are fastened, the deformation amount of the gasket is accurately controlled through the height limitation of the concave surface. The air-tightness effect of the gasket is optimized, and the service life is greatly prolonged. Meanwhile, with the mating of concave surface, the locating state of the gasket is more stable for improved applicability.
Although the invention has been explained in relation to its preferred embodiment, it is to be understood that many other possible modifications and variations can be made without departing from the spirit and scope of the invention as hereinafter claimed.
The features and the advantages of the present invention will be more readily understood upon a thoughtful deliberation of the following detailed description of a preferred embodiment of the present invention with reference to the accompanying drawings.
The fuel cell A comprises a plurality of bipolar plates 10, and a gas guidance and reaction layer 20 overlapped with the bipolar plates 10. Gas channel 11 is placed laterally onto the bipolar plates 10 corresponding to the gas guidance and reaction layer 20. The gas channel 11 has a serpentine pattern.
The first main gas channel 31 and second main gas channel 32 are arranged on the bipolar plates 10 at a distance from the gas channel 11. Different reacting gases, such as hydrogen and oxygen, are guided separately. The first and second main gas channels 31, 32 are connected with the gas channel 11 via a passage 12. The gasket 40 is placed between the bipolar plates 10 and gas guidance and reaction layer 20. Referring to
The concave surface 13 is placed laterally on the bipolar plates 10 corresponding to the gas guidance and reaction layer 20. The concave surface 13 is properly positioned for mating with the gasket 40. In practice, the depression height of the concave surface 13 is slightly smaller than the thickness of the gasket 40. When the bipolar plates 10 and gas guidance and reaction layer 20 are coupled to yield a pressure on the gasket 40, the limited height of the concave surface 13 allows the gasket 40 to be accurately controlled to realize optimum elastic force, air-tightness effect and strong endurance.
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Based upon above-specified structures, the present invention is operated as follows:
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