Abstract: A method for shutting down a fuel cell system having at least one fuel cell, especially a fuel cell provided with a proton exchanging membrane, anode and cathode inlets, anode and cathode outlets, an anode recirculation circuit, a device which is operated according to the Venturi principle and is used to convey the gas in the anode recirculation circuit, and a hydrogen and air supply is disclosed. A method characterized by low emission values and high efficiency is provided. The hydrogen supply to the anode is interrupted during shutdown of the fuel cell system and the current generated from the residual hydrogen is supplied to an electric consumer.

Abstract: In a method and apparatus for wetting a fuel cell unit on the basis of a predetermined dew point nominal value as a function of the operating state of the fuel cell unit, a corrected dew point nominal value is determined using a predetermined dew point nominal value, a component-specific correction value, and a process correction value. The corrected dew point nominal value is used to set the required amount of water for optimum wetting of the fuel cell unit.

Abstract: A fuel cell system is provided having at least one switching means (16, 17, 18) for reversing the direction of a flow of at least one working medium in a fuel cell unit (10), with the fuel cell unit (10) having a cathode (11), an anode (12) and a cooling water device (13) in a housing (26). Advantageously more reliable operation with less component complexity is made possible by the switching means (16, 17, 18) being arranged outside the housing (26).

Abstract: An injector for high-pressure injection of fuel in self-igniting internal combustion engines includes an actuator valve for opening and closing the injector; a nozzle needle, which in the closed state of the injector closes at least one injection opening; a metering valve, which establishes a hydraulic communication between the actuator valve and the relief chamber of the injector; a pressure holding device, which serves to maintain a static pressure required for the metering valve; and a first control quantity line for control quantities that flow via the actuator valve, and a second control quantity line for control quantities that flow via the metering valve. The pressure holding device dynamically separates the control quantities of the metering valve from the control quantities of the actuator valve by means of a hydraulic fluctuation damper.

Abstract: The fuel injection system having one high-pressure fuel pump and one fuel injection valve for each engine cylinder in which the pump piston defines a work chamber, which communicates with a pressure chamber of the fuel injection valve. A control valve controls connection of the pump work chamber with a relief chamber and having a second control valve controls a connection of a control pressure chamber, which communicates with the pump work chamber defined by a control piston with a relief chamber is controlled, and in which connection a throttle restriction is provided.

Abstract: The fuel injection system has one high-pressure fuel pump (10) and one fuel injection valve (12), communicating with it, for each cylinder of the internal combustion engine. A pump piston (18) of the high-pressure fuel pump (10) defines a pump work chamber (22), which communicates with a pressure chamber (40) of the fuel injection valve (12); the fuel injection valve has an injection valve member (28), by which injection openings (32) are controlled and which is movable in an opening direction (29) counter to a closing force by the pressure prevailing in the pressure chamber (40). By means of a control valve (80), a connection (74) of the pump work chamber (22) with a relief chamber (24) is controlled, and having a second control valve (80), by which a connection (74) of a control pressure chamber (62), which communicates with the pump work chamber (22) and is defined by a control piston (60), with a relief chamber (24) is controlled, in which connection a throttle restriction (75) is provided.

Abstract: The invention relates to an injector for high-pressure injection of fuel in self-igniting internal combustion engines. The injector includes an actuator valve for opening and closing the injector; a nozzle needle (17), which in the closed state of the injector closes at least one injection opening (18); a metering valve (4), which establishes a hydraulic communication between the actuator valve and the relief chamber (6) of the injector; a pressure holding device (33), which serves to maintain a static pressure required for the metering valve (4); and a first control quantity line (29) for control quantities (34) that flow via the actuator valve, and a second control quantity line (43) for control quantities (35) that flow via the metering valve (4). The pressure holding device (33) dynamically separates the control quantities (35) of the metering valve (4) from the control quantities (34) of the actuator valve by means of a hydraulic fluctuation damper.