Electrolysis: processes – compositions used therein – and methods – Electrolytic erosion of a workpiece for shape or surface... – Using mask
Reexamination Certificate
2001-06-28
2003-07-15
Ryan, Patrick (Department: 1745)
Electrolysis: processes, compositions used therein, and methods
Electrolytic erosion of a workpiece for shape or surface...
Using mask
C205S670000, C205S672000, C204S22400M, C204S275100
Reexamination Certificate
active
06592743
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a method and equipment for producing a gas separator of fuel cells, which is integrated with a gas flow channel.
2. Description of the Related Art
Fuel cells generating electric power in response to the feed of fuel gas are generally manufactured by integrating plural electric cells. A separator lies between adjacent cells for the separation of both of them and additionally takes a role of material for forming a gas flow channel through which fuel gas is fed to the respective cells. With regard to techniques for forming a recessed portion (groove or depression) changing into a gas flow channel in a separator integrated with a gas flow channel like this, cutting method for machine cutting a metal plate changing into a base material of a separator to form grooves and the like, press working method for subjecting a metal plate changing into a base material of a separator to press working to form grooves and the like by stamping, and etching method for subjecting a metal plate changing into base material of a separator to etching to form chemically grooves and the like are known.
BRIEF SUMMARY OF THE INVENTION
According to the cutting method, processing accuracy of grooves and depressions can be improved. In contrast with this, this method has such drawbacks that if the shape of a gas flow channel becomes complicated, gross floor area becomes increased, and at the same time, great time is necessary for processing and yet, production cost becomes high. The press working method is convenient for mass production because of high processing accuracy and very small fluctuation between lots. However, this method has such drawbacks that production cost of a press die is high, work hardening as well as local change of wall thinning cannot be avoided, and sufficient guarantee cannot be given in respect the durability, i.e., changing with the lapse of time such as corrosion resistance and the like. Further, according to the above described conventional etching method, an etching solution such as electrolytic solution and the like is prepared in a fixed vessel, and a metal plate to be changed into a base material of a separator is immersed in the etching solution to carry out etching. However, such a dipping-like method shows a tendency that a long processing time is required because the etching solution as well as reaction products migrates slowly around the face to be processed. Particularly, in case of electrolytic etching by the use of electrodes, even when a feed current is increased, a fresh etching solution proportional to the current is hard to be fed to the face to be processed within a short time. Accordingly, such drawbacks are caused that a long period of time is required for making grooves, in particular in case where the groove is required to have a depth of several hundred micrometers, productivity is low, and production cost becomes high.
It is an object of the present invention to provide a method for producing a separator, of fuel cells, which is capable of producing a separator integrated with a gas flow channel efficiently at comparatively low costs and which causes no trouble in respect of processing accuracy and durability. It is also an object of the present invention to provide an equipment for producing a separator of fuel cells with the object of putting the production method into practice effectively.
According to a first aspect of the present invention, there is provided a method for producing a separator for use in fuel cells, which is integrated with a gas flow channel, and characterized by comprising: a masking step of partially masking the face to be processed of a base material of a separator; an electrolytic processing step of disposing an electrode oppositely to the masked face of the base material to be processed, injecting and feeding an electrolytic solution to the face to be processed from a direction which makes almost a right angle with the face to let the electrolytic solution lie between the face and the electrode, and electrolyzing the unmasked portion of the face under the condition of feeding electricity to the electrode and at the same time to the base material to form recessed portions for making the gas flow channel; and a mask-removing step of removing a mask from the face after forming the recessed portions.
According to this constitution, an electrolytic solution is injected and fed to the partially masked face to be processed of a base material of a separator from a direction which is almost at right angles to the face so that the electrolytic solution instantly spreads all over the area between the face and the electrode. Accordingly, the whole face to be processed can be covered with the electrolytic solution all around. In particular, as the feed direction of an electrolytic solution is almost perpendicular to the face to be processed, the electrolytic solution can be fed directly to the central area of the face too. In this point, the feed efficiency of the electrolytic solution is very good as compared with the case where the electrolytic solution is poured in parallel to the face to be processed from the end of the base material. As a result, by virtue of the feed action of the electrolytic solution induced by injection, a sufficient amount of fresh electrolytic solution is fed one after another between the face to be processed and the electrode, and at the same time, unnecessary electrolysis products are washed away over the face to the outside. Accordingly, the electrochemical reaction at the unmasked portion of the face is promoted. Consequently, desired recessed portions for making a gas flow channel can be formed on the unmasked portion of the face with high energy efficiency within comparatively short time.
According to a second aspect, in the method of the first aspect, the method is characterized in that the electrode is a plane-facing electrode to be disposed oppositely to the face to be processed at a predetermined interval, and has a nozzle to inject and feed an electrolytic solution to the face to be processed from a direction which is almost perpendicular to the face. In this method, in connection with the feature that an electrolytic solution is injected and fed to the face to be processed from a direction that is almost perpendicular to the same face, it is preferable to provide an electrolytic solution injection feed structure in the electrode facing the face to be processed. Taking this point into consideration, the second aspect is contrived.
According to a third aspect, in the method recited in the first or second aspect, the method is further characterized in that the base material of a separator has a shape of a flat plate, both faces of the base material being to be processed, and an electrolytic solution is fed toward the both faces by injection from a direction which is almost perpendicular to each of the both faces. Ac cording to this method, recessed portions for making a gas flow channel can be formed simultaneously on both sides of the flat base material of a separator, and accordingly, working efficiency improves. In addition to this, the flat base material can be held stably in position during the electrolytic processing so that electrolytic processing accuracy can be improved. Namely, in case of injecting an electrolytic solution at the same time to both the faces to be processed in/from a direction which is almost perpendicular to the respective face, both of the liquid injections are opposite to each other, and when both injection pressures are almost the same with each other, the liquid injections have a relation that they mutually support the backside of the base material and cancel mutual effects thereby. Accordingly, the flat base material can be held stably in position, and the respective face to be processed can undergo uniform electrolysis.
According to a fourth aspect, in the method of the first to third aspects, the method is characterized in that the base material is maintained almost in a vertical direction, and
Dewaki Kenji
Dewaki Shinji
Kimata Ryuta
Kuwabara Youhei
Matsukawa Masanori
Aisin Takaoka Co. Ltd.
Burns Doane , Swecker, Mathis LLP
Parsons Thomas H.
Ryan Patrick
LandOfFree
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