Abstract: The invention relates to a polar plate (10, 12), particularly an end plate (10) or a bipolar plate (12), for a fuel cell stack (14) comprising at least one flow field (16) accessible from at least one side of the polar plate (10, 12). In this connection it is, according to the invention, contemplated that the at least one flow field (16) is accessible via a plurality of access orifices (18). The invention further relates to a termination unit and a repetitive unit for a fuel cell stack as well as a fuel cell stack.

Abstract: The invention relates to a reformer for a fuel cell system for generating a reformate comprising a plurality of function units for treating the fuel, at least one function unit being adapted to a first type of fuel. In this arrangement the invention is characterized to advantage in that the function unit adapted to the first type of fuel can be releasably coupled to the reformer as a module by means of an interface which is also designed to couple a replacement function unit instead of the function unit adapted to the first type of fuel, the replacement function unit being adapted to a second type of fuel different from the first type of fuel. The invention relates furthermore to a function unit for such a reformer, to a fuel cell system having such a reformer and to a motor vehicle having such a fuel cell system.

Abstract: The invention relates to a high temperature fuel cell stack (10) retained by a temporary retaining device. According to the invention it is contemplated that the temporary retaining device (12-22) consists of a plastic material burning at a temperature which is lower than the operating temperature of the high temperature fuel cell stack (10). The invention also relates to a method for temporarily retaining a high temperature fuel cell stack (10) and a method for removing a temporary retaining device (12-22) of a high temperature fuel cell stack (10). The invention further relates to the use of per se known plastic elements (12-22) as a temporary retaining device for a high temperature fuel cell stack (10).

Abstract: A fuel cell stack (10) with fuel cells (12), a clamping device (16) and a heat insulating device (14), the clamping device (16) having pressure distribution elements (18) and the fuel cells (12) being located between the pressure distribution elements (18). The fuel cell stack (10) is characterized by the fact that the heat insulating device (14) is located between the fuel cells (12) and the clamping device (16).

Abstract: A contact element (7) for a fuel cell stack for connecting the electrodes (3, 4) of two adjacent fuel cells. The contact element is has at least one sealed cavity which is filled with a gas. The gas continuously imparts elasticity to the contact element (7) even at high temperatures, by which reliable contact-making of the electrodes (3, 4) is ensured. Furthermore, a fuel cell stack in which a contact element (7) is used has the anode of one fuel cell electrically connected to the cathode of an opposite fuel cell via the contact element. The contact elements can be tubes or can be formed of corrugated plates that are arranged in mirror image fashion forming channels and are connected at least at an outer area so as to seal the channels relative to the outside.

Abstract: A process and device for determination of the lambda value (?actual) of reformate (10) which is to be supplied to a fuel cell stack (12), by determining the lambda value (?actual) of the no-load voltage (U0) of the voltage on at least one fuel cell element (14). Furthermore, a process and device for lambda control of a reformer, utilizes the process and device for determining the lambda value to controller an actuator of a lambda-controlled reformer (16) for reaction of at least fuel (20) and air (22) into reformate (10), the reformer being connected to a fuel cell stack (12) to supply reformate (10) form the reformer (16) to the fuel stack (12).