Chemistry: electrical current producing apparatus – product – and – With pressure equalizing means for liquid immersion operation
Reexamination Certificate
2000-09-11
2003-12-30
Gulakowski, Randy (Department: 1746)
Chemistry: electrical current producing apparatus, product, and
With pressure equalizing means for liquid immersion operation
C429S006000, C429S006000, C429S006000
Reexamination Certificate
active
06670068
ABSTRACT:
The present invention relates to a fuel cell unit which comprises a cathode-anode-electrolyte unit and a contact plate which is in electrically conductive contact with the cathode-anode-electrolyte unit (CAE unit).
Fuel cell units of this type are known from the state of the art.
As a rule, several such fuel cell units are combined to form a composite block of fuel cells, in which the fuel cell units follow one another along a stacking direction.
In the cathode-anode-electrolyte unit, an electrochemical reaction takes place during the operation of the fuel cell unit, during the course of which electrons are supplied to the anode of the CAE unit and electrons withdrawn from the cathode of the CAE unit for the ionization of oxygen atoms. The contact plates arranged between the CAE units of two consecutive fuel cell units serve to balance the charge between the cathode of the one fuel cell unit and the anode of the adjacent fuel cell unit in order to supply the cathode with the electrons required for the ionization. Electric charges may be tapped from the edge-side contact plates of the composite block of fuel cells in order to supply them to an external useful current circuit.
The contact plates used with the known fuel cell units are metal plates which are milled or eroded from the entire plate and between which the CAE units are inserted so that these contact plates serve at the same time to hold the CAE units, as well. Furthermore, these plates are provided with channels which serve for the passage of fluids (combustible gas, oxidation agent and/or refrigerant) through the fuel cell unit.
These known fuel cell units are very complicated to produce and thus suitable only for small quantities.
The object underlying the present invention is therefore to create a fuel cell unit of the type specified at the outset which requires only small production resources and is thus suitable for large-scale production.
This object is accomplished in accordance with the invention, in a fuel cell unit with the features of the preamble to claim 1, in that the fuel cell unit comprises a fluid guiding element which is connected to the contact plate in a fluid-tight manner, forms a boundary of a fluid chamber having fluid flowing through it during operation of the fuel cell unit and is designed as a shaped sheet metal part.
Such a shaped sheet metal part may be produced from an essentially flat sheet metal blank by means of one or more shaping processes, in particular, by means of embossing and/or deep drawing. These production methods are considerably more suitable and more inexpensive for a large-scale production than the production of solid metal plates by way of milling or erosion.
In addition, it is possible to save on material and weight due to the use of shaped sheet metal parts.
The fluid flowing through the fluid chamber can be a combustible gas, an oxidation agent or a refrigerant.
In particular, it may be provided for the fluid chamber to be surrounded, apart from by the fluid guiding element, by the contact plate and by the cathode-anode-electrolyte unit.
In a preferred configuration of the invention it is provided for the cathode-anode-electrolyte unit of the fuel cell unit to be arranged on the fluid guiding element.
In particular, it may be provided for the cathode-anode-electrolyte unit to be arranged between the fluid guiding element, on the one hand, and the contact plate of the same fuel cell unit or an adjacent fuel cell unit, on the other hand.
The inventive fuel cell unit is already particularly simple to handle prior to the assembly of the composite block of fuel cells when the cathode-anode-electrolyte unit is held between the fluid guiding element and the contact plate of the same fuel cell unit.
Alternatively hereto, it may also be provided for the cathode-anode-electrolyte unit to be designed as a coating on the fluid guiding element or on the contact plate of the fuel cell unit.
It is particularly favorable when not only the fluid guiding element but also the contact plate is designed as a shaped sheet metal part. In this case, the contact plate of the fuel cell unit may also be produced in a simple manner by way of embossing and/or deep drawing from an essentially flat sheet metal blank which is more suitable and more inexpensive for a large-scale production than the production of solid contact plates by way of milling or erosion.
The contact plate and the fluid guiding element may, in this case, form a two-part shell of the fuel cell unit which surrounds the cathode-anode-electrolyte unit.
The inventive construction of a fuel cell unit is particularly suitable for so-called high-temperature fuel cell units which have an operating temperature of up to 950° C. and can be operated, without any external reformer, directly with a hydrocarbonaceous combustible gas, such as, for example, methane or natural gas or alternatively hereto, using an external reformer, with a diesel or petroleum motor fuel.
For use in such a high-temperature fuel cell unit the shaped sheet metal parts, from which the fluid guiding element and also, where applicable, the contact plate of the fuel cell unit are formed, are produced from a sheet metal material which is chemically resistant at the resulting temperatures of up to 950° C. in relation to the components of the combustible gas, the combustion air supplied and a refrigerant supplied where applicable (for example cooling air).
High-grade steel sheets resistant to high temperatures or steel sheets coated with an inorganic or ceramic material are particularly suitable for this purpose.
Furthermore, a sheet metal material is preferably selected which has a thermal coefficient of expansion compatible with that of the CAE unit.
The thickness of the sheet metal material used is preferably at the most approximately 3 mm, in particular, at the most approximately 1 mm.
In order to achieve a reliable connection between the contact plate and the fluid guiding element of the same fuel cell unit which is also resistant and gas-tight at high temperatures, it is preferably provided for the fluid guiding element and the contact plate to be connected to one another by way of welding, preferably by laser welding or by electron beam welding.
Alternatively or in addition hereto it may be provided for the fluid guiding element and the contact plate to be connected to one another by way of soldering, preferably by hard soldering.
In order to make the required compensation of charges between the CAE units of fuel cell units adjacent to one another possible in a simple manner it is provided in a preferred configuration of the inventive fuel cell unit for the fluid guiding element to have an opening for the passage of contact elements (e.g. of an adjacent fuel cell unit) to the cathode-anode-electrolyte unit.
In order to be able to hold the CAE unit between the fluid guiding element and the contact element of the fuel cell unit without shorting the anode and the cathode of the same fuel cell unit with one another, it is advantageously provided for the fluid guiding element to abut on the cathode-anode-electrolyte unit via an electrically insulating seal.
In a preferred configuration of the invention, the fluid guiding element is designed as a fluid guiding frame which abuts on the cathode-anode-electrolyte unit along the entire edge thereof via the electrically insulating seal.
It is particularly favorable when the seal between the fluid guiding element and the CAE unit comprises mica.
Alternatively or in addition hereto, it may be provided for the seal between the CAE unit and the fluid guiding element to comprise a flat seal.
Alternatively or in addition hereto, it may be provided for the seal between the CAE unit and the fluid guiding element to comprise a coating on the fluid guiding element and/or on the cathode-anode-electrolyte unit.
Such a coating may be applied, for example, by the screen printing method, by roller coating or by spray coating onto the fluid guiding element or the cathode-anode-electrolyte unit.
Inorganic or ceramic sealing media, which are
Crepeau Jonathan
ElringKlinger AG
Gulakowski Randy
LandOfFree
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