Patent ID: 7067212

Claim:
A fuel cell system comprising: a fuel cell stack consisting of a plurality of fuel cells and having an anode side with an anode inlet and an anode outlet and also a cathode side with a cathode inlet and a cathode outlet; a source of one of oxygen or air at said cathode side for the delivery of one of oxygen and air via said cathode inlet to said cathode side of said fuel cell stack; a source of a gaseous fuel for said anode side of said fuel cell stack, said source being adapted to deliver fuel at a higher pressure level; a feed-line which leads from said source of gaseous fuel to said anode inlet; at least one mechanical pressure regulating valve provided in said feed-line, said mechanical pressure regulating valve having a valve member and a spring for exerting a spring bias on said valve member and being adapted to regulate the fuel from said higher pressure level down to a lower pressure level; a control valve arranged downstream of said mechanical pressure regulating valve and adapted to determine a mass flow of fuel supplied to the anode side of said fuel cell stack from said source of gaseous fuel; an anode outlet valve which is connected to said anode outlet of the fuel cell stack; and a control line which leads, from one of a point between the control valve and the anode exhaust gas valve at said anode side of said fuel cell stack and a point at said cathode side of said fuel cell stack downstream of said source of one of oxygen and air, to said mechanical pressure regulating valve and being connected to it to assist said spring bias.