Abstract: A proton exchange membrane fuel cell comprising a proton transmissive membrane, a catalytic anode layer on one face of the membrane, a catalytic cathode layer on the other face of the membrane, and a gas distribution layer on each of the cathode and anode layers defining a gas flow field extending over each of the catalytic layers. Each of the gas distribution layers comprises a layer of open cell conductive foam material which is divided into a plurality of generally parallel segments extending from one edge of the fuel cell to an opposite edge of the fuel cell whereby to define a plurality of generally parallel porous reactant paths extending across each catalytic layer. The segments may be defined by selectively varying the porosity of the foam material or selectively varying the thickness of the foam material.

Abstract: An apparatus for monitoring hydrogen and optionally a non-hydrogen gas including carbon monoxide. The apparatus includes a sensor assembly consisting of a plurality of electrochemical cells sequentially arranged in a path of the hydrogen-containing gas stream. Reaction and consumption of hydrogen at catalytically reactive surface areas of the cells generates a current which is proportional to the amount of hydrogen in the gas stream entering the sensor.

Abstract: A method of making a membrane electrode assembly is provided. The method includes using a porous support to control the drying of the electrode, and the use of wettable and non-wettable solvents to control the seepage of ionomer into the porous support.

Abstract: In one aspect, the present invention provides a method for operating a fuel cell system. The system comprises a reactor having one or more catalytic beds and is fed a hydrocarbon fuel along with air and steam. Where more than one catalytic bed is present, such catalytic beds are preferably arranged sequentially such that the outlet from one bed enters the inlet of the next bed. The catalytic beds are the regions where reactions among the hydrocarbon, air, and steam are catalyzed within the reactor. The method comprises supplying a stream of a fuel and air mixture to the reactor which is lean. The mixture is lean in that it has an excess amount of oxygen relative to the stoichiometric amount required for reaction with the fuel. The reactions occurring with the lean mixture heat the reactor. When there is more than one catalytic bed, the hot gases generated from one catalytic bed can be used to heat other catalytic beds.

Abstract: A bipolar plate assembly for a PEM fuel cell having a serpentine flow field formed on one side and an interdigitated flow field formed on the opposite side such that a single plate member is usable as an anode current collector and a cathode current collector of adjacent fuel cells. The bipolar plate assembly further includes a staggered seal arrangement to direct gaseous reactant flow through the fuel cell such that the seal thickness is maximized while the repeat distance between adjacent fuel cells is minimized.

Abstract: A method and apparatus for injecting oxygen into a fuel cell reformate stream to reduce the level of carbon monoxide while preserving the level of hydrogen in a fuel cell system.

Abstract: A regenerative braking system and method for a batteriless fuel cell vehicle includes a fuel cell stack, a plurality of ancillary loads, and a regenerative braking device that is coupled to at least one wheel of the vehicle. The regenerative braking device powers ancillary loads when the vehicle is coasting or braking. The fuel cell powers the loads when the vehicle is accelerating or at constant velocity. The regenerative braking device dissipates power in an air supply compressor when the vehicle is traveling downhill to provide brake assistance. The compressor can be run at high airflow and high pressure to create an artificially high load. A bypass valve is modulated to adjust the artificially high load of the compressor. A back pressure valve protects the fuel cell stack from the high airflow and pressure. A controller controls a brake torque of the regenerative braking device as a function of vehicle speed and modulates the bypass valve.

Abstract: A water separator especially suitable for use in a vehicular fuel cell system. The separator comprises a housing defining an inlet, an outlet, and a longitudinal through passage extending therebetween. A central shaft extends along the passage and a plurality of modular baffles are stacked on the shaft. Each baffle includes an annular hub portion received on the shaft and a plurality of circumferentially spaced vanes extending outwardly from the hub portion to block a portion of the cross-sectional area of the passage. An actuator drives one end of the shaft and alternate baffles are keyed to the shaft so that actuation of the actuator relatively rotates the modular baffles to selectively vary the cross-sectional blockage defined by the baffles.

Abstract: A method of operating a combustor to heat a fuel processor in a fuel cell system, in which the fuel processor generates a hydrogen-rich stream a portion of which is consumed in a fuel cell stack and a portion of which is discharged from the fuel cell stack and supplied to the combustor, and wherein first and second streams are supplied to the combustor, the first stream being a hydrocarbon fuel stream and the second stream consisting of said hydrogen-rich stream, the method comprising the steps of monitoring the temperature of the fuel processor; regulating the quantity of the first stream to the combustor according to the temperature of the fuel processor; and comparing said quantity of said first stream to a predetermined value or range of predetermined values.

Abstract: A method for controlling the power and temperature and fuel source of a combustor in a fuel cell apparatus to supply heat to a fuel processor where the combustor has dual fuel inlet streams including a first fuel stream, and a second fuel stream of anode effluent from the fuel cell and reformate from the fuel processor. In all operating modes, an enthalpy balance is determined by regulating the amount of the first and/or second fuel streams and the quantity of the first air flow stream to support fuel processor power requirements.

Abstract: An electrochemical fuel cell stack comprising an upper end plate assembly; a lower end plate assembly; at least one electrochemical fuel cell assembly interposed between the upper and lower end plate assemblies; and a clamp mechanism operative to compressively clamp the stack. A plurality of screws threaded through threaded bores in the upper end plate at spaced locations in the upper end plate and bearing at their lower ends on an upper face of a distributor plate are selectively tightened to provide a substantially uniform torque in each screw whereby to assure uniform compressive loading across the area of the distributor plate and thereby across the area of the fuel cell assembly.

Abstract: A method and apparatus for controlling the temperature of a combustor in a fuel cell apparatus includes a fast acting air bypass valve connected in parallel with an air inlet to the combustor. A predetermined excess quantity of air is supplied from an air source to a series connected fuel cell and combustor. The predetermined excess quantity of air is provided in a sufficient amount to control the temperature of the combustor during start-up of the fuel processor when the load on the fuel cell is zero and to accommodate any temperature transients during operation of the fuel cell.

Abstract: In one aspect, the invention provides a method of operating a combustor to heat a fuel processor to a desired temperature in a fuel cell system, wherein the fuel processor generates hydrogen (H2) from a hydrocarbon for reaction within a fuel cell to generate electricity. More particularly, the invention provides a method and select system design features which cooperate to provide a start up mode of operation and a smooth transition from start-up of the combustor and fuel processor to a running mode.

Abstract: A venting methodology and pressure sensing and vent valving arrangement for monitoring anode bypass valve operating during the normal shutdown of a fuel cell apparatus of the type used in vehicle propulsion systems. During a normal shutdown routine, the pressure differential between the anode inlet and anode outlet is monitored in real time in a period corresponding to the normal closing speed of the anode bypass valve and the pressure differential at the end of the closing cycle of the anode bypass valve is compared to the pressure differential at the beginning of the closing cycle. If the difference in pressure differential at the beginning and end of the anode bypass closing cycle indicates that the anode bypass valve has not properly closed, a system controller switches from a normal shutdown mode to a rapid shutdown mode in which the anode inlet is instantaneously vented by rapid vents.

Abstract: A steering knuckle structure that makes it possible to produce a light weight steering knuckle from a light metal alloy with a high degree of rigidity. A bracket for fixing a telescopic strut is provided at a vertically extending bracket wall which is supported by a bridge and wherein the area between the bridge and the bracket wall is open in a peripheral direction of the hub of the steering knuckle.

Abstract: A venting methodology and system for rapid shutdown of a fuel cell apparatus of the type used in a vehicle propulsion system. H2 and air flows to the fuel cell stack are slowly bypassed to the combustor upon receipt of a rapid shutdown command. The bypass occurs over a period of time (for example one to five seconds) using conveniently-sized bypass valves. Upon receipt of the rapid shutdown command, the anode inlet of the fuel cell stack is instantaneously vented to a remote vent to remove all H2 from the stack. Airflow to the cathode inlet of the fuel cell stack gradually diminishes over the bypass period, and when the airflow bypass is complete the cathode inlet is also instantaneously vented to a remote vent to eliminate pressure differentials across the stack.

Abstract: A method is provided for the shutdown of a fuel cell system to relieve system overpressure while maintaining air compressor operation, and corresponding vent valving and control arrangement. The method and venting arrangement are employed in a fuel cell system, for instance a vehicle propulsion system, comprising, in fluid communication, an air compressor having an outlet for providing air to the system, a combustor operative to provide combustor exhaust to the fuel processor.

Abstract: A system for controlling the humidity level of a fuel cell is provided. The system includes a fuel cell, a humidifier for humidifying the fuel cell, and a controller for determining the humidity level of the fuel cell and controlling the humidifier in response to the determined humidity level. The resistance of the fuel cell varies as a function of the humidity level of the fuel cell. Thus, in a preferred system, the controller calculates the resistance of the fuel cell via measurements of AC preferred voltage and current components to determine the humidity level of the fuel cell. A method for controlling the humidity level of a fuel cell is also provided. The steps of the method include: determining the humidity level of the fuel cell, and humidifying the fuel cell in response to the determined humidity level.

Abstract: There is provided a multilayer gas distribution structure for use with a membrane electrode assembly of a PEM fuel cell. The layers of the multilayer diffusion structure have selected chemical and physical properties. Together, the layers facilitate transport of reactant gas to the electrode while improving water management.

Abstract: A DC/DC converter for a fuel cell includes an input node for receiving DC supply power from the fuel cell. An output node provides a DC output voltage. An inductor has inductance which varies with respect to inductor current. The inductor includes a first terminal and a second terminal. The first terminal is coupled with the input node for receiving DC supply power from the fuel cell. A switch is coupled between the second terminal of the inductor and ground. A control circuit switches the switch between an open position and a closed position.