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  Fuel cell systemUSPTO Application #: 20060210853Title: Fuel cell system Abstract: A fuel cell system (1) which includes: a fuel cell (2) to be supplied with a gas for power generation, the gas unused for the power generation to be discharged out of the fuel cell (2); a circulation flow path (8) through which the discharged gas is resupplied to the fuel cell (2); a variable flow rate circulation pump (6) for circulating the gas through the circulation flow path (8); a valve (7) for discharging the gas in the circulation flow path (8) to the outside thereof; a voltage sensor (22) for measuring voltage of the fuel cell (2); and a controller (32) for controlling the circulation pump (6) and the valve (7). The circulation pump (6) and the valve (7) are controlled based on the voltage (CV) measured by the voltage sensor (22). (end of abstract)
Agent: Foley And Lardner LLP Suite 500 - Washington, DC, US Inventor: Takashi Fukuda USPTO Applicaton #: 20060210853 - Class: 429023000 (USPTO) Related Patent Categories: Chemistry: Electrical Current Producing Apparatus, Product, And Process, Fuel Cell, Subcombination Thereof Or Methods Of Operating, Automatic Control Means, Electrical Output Dependent The Patent Description & Claims data below is from USPTO Patent Application 20060210853. Brief Patent Description - Full Patent Description - Patent Application Claims
TECHNICAL FIELD [0001] The present invention relates to a fuel cell system, more particularly a purge control in a fuel cell system having an anode gas circulation system. BACKGROUND ART [0002] A fuel cell is an electrochemical device to convert chemical energy of fuel gas such as hydrogen gas and oxidant gas containing oxygen supplied thereto, directly to electric energy which is extracted from electrodes provided on both sides of an electrolyte thereof. A fuel cell using a solid polymer electrolyte membrane has low operation temperature and can be easily handled, and therefore, it has been a focus of attention as a power source for an electric vehicle. [0003] The solid polymer electrolyte membrane is required to be retained in a moderately humidified state in order to exert sufficient hydrogen ion conductivity. The fuel gas or the oxidant gas or the both gases are humidified to be supplied to the fuel cell. Thus, water added for the humidification and water produced by a power generation reaction in the fuel cell are condensed and may cause clogging or blocking of a gas passage in the fuel cell, depending on operating conditions of the fuel cell. [0004] Moreover, in a fuel cell using air as the oxidant gas, nitrogen contained in the air passes through a solid polymer membrane thereof, and accumulates in a fuel gas circulation system. Consequently, a fuel gas partial pressure decreases at a fuel electrode of the fuel cell, lowering operation efficiency thereof. In order to resolve the clogging and the accumulation of nitrogen, purging is performed for the fuel gas circulation system. [0005] Japanese Patent Laid-Open Publication No. 2002-243417 discloses a fuel cell system which removes impurities accumulated in a hydrogen gas circulation system by opening a purge valve provided in the system and releasing anode off-gas to outside of the system. DISCLOSURE OF INVENTION [0006] In the system described above, however, even in the case that clogging in the hydrogen gas circulation system is required to be resolved, hydrogen containing fuel gas is released to the outside of the system through the purge valve, whereby operation efficiency thereof is lowered. [0007] The present invention was made in the light of the problem. An object of the present invention is to provide a fuel cell system which removes clogging of gas passages in the fuel cell without lowering the operation efficiency thereof. [0008] An aspect of the present invention is a fuel cell system comprising: a fuel cell to be supplied with a gas for power generation, the gas unused for the power generation to be discharged out of the fuel cell; a circulation flow path through which the gas discharged out of the fuel cell is resupplied to the fuel cell; a variable flow rate circulation pump for circulating the gas through the circulation flow path; a valve for discharging the gas in the circulation flow path to the outside of the circulation flow path; a voltage sensor for measuring voltage of the fuel cell; and a controller for controlling the circulation pump and the valve, wherein the circulation pump and the valve are controlled based on the voltage measured by the voltage sensor. BRIEF DESCRIPTION OF THE DRAWINGS [0009] The invention will now be described with reference to the accompanying drawings wherein: [0010] FIG. 1 is a block diagram of a fuel cell system according to a first embodiment of the present invention; [0011] FIG. 2 shows relationship between fuel cell load and operation pressure of a fuel cell of the first embodiment; [0012] FIG. 3 shows relationship between fuel cell load and average cell voltage of the fuel cell of the first embodiment; [0013] FIG. 4 is a flowchart of a purge operation of the first embodiment; [0014] FIG. 5 shows a relationship between fuel cell load and hydrogen gas circulation flow rate Qh of the first embodiment; [0015] FIG. 6 is a flowchart of a purge operation of a second embodiment of the present invention; [0016] FIG. 7 shows a relationship between fuel cell load and purge flow rate Qp of the second embodiment; and [0017] FIG. 8 is a flowchart of a purge operation of a third embodiment of the present invention. BEST MODE FOR CARRYING OUT THE INVENTION [0018] Embodiments of the present invention will be described in detail with reference to the drawings. In all of the embodiments, described is a fuel cell system suitable for a fuel cell vehicle. First Embodiment Continue reading... Full patent description for Fuel cell system Brief Patent Description - Full Patent Description - Patent Application Claims Click on the above for other options relating to this Fuel cell system patent application. ###  How KEYWORD MONITOR works... a FREE service from FreshPatents1. Sign up (takes 30 seconds). 2. Fill in the keywords to be monitored. 3. Each week you receive an email with patent applications related to your keywords. Start now! - Receive info on patent apps like Fuel cell system or other areas of interest. ### Previous Patent Application: Fuel cell power generating system with learning control Next Patent Application: Flow field plate arrangement Industry Class: Chemistry: electrical current producing apparatus, product, and process ### FreshPatents.com Support Thank you for viewing the Fuel cell system patent info. IP-related news and info Results in 3.31356 seconds Other interesting Feshpatents.com categories: Accenture , Agouron Pharmaceuticals , Amgen , AT&T , Bausch & Lomb , Callaway Golf |
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