Gm Global Technolgoy Operations, Inc.

Robert L Fuss

Bhaskar Sompalli

Brian K Brady

Eric L Thompson

James H Lee

Michael W Murphy

Carl M Marsiglio

Gerald W Fly

Bruce Jeffrey Clingerman

Thomas W Tighe

Kenneth L Kaye

Robert Nash Carter

Jay K Sofianek

Lewis J DiPietro

Allan M Ruckey

James H Rush

John F Nally

John E Williams

A fuel cell system is disclosed that employs a humidifier and an oxygen sensor for measuring the oxygen concentration in the cathode exhaust gas from the fuel cell stack to determine a system diagnostic, such as a fluid leak from or across the humidifier.

Fuel cell humidifier diagnostic

Combustion heaters having internal combustion chambers are located adjacent the end cells of a stack of fuel cells to directly, conductively heat the end cells during cold start-up of the stack. Similar heater(s) may also be located within the stack when cold starting under extremely cold conditions. A method of combustion thawing a fuel cell stack is described.

Combustion-thawed fuel cell

A current sensor assembly that monitors current flow through segments of a fuel cell stack. The current sensor assembly includes a first plate including a first non-conductive substrate having a first conductive path therethrough and that is in electrical communication with a first segment of the fuel cell stack. A second plate includes a second non-conductive substrate having a second conductive path therethrough and that is in electrical communication with a second segment of the fuel cell stack. A first current sensor is operably disposed between the first plate and the second plate and facilitates a first current flow between the first conductive path and the second conductive path. The first current sensor generates a first current signal based on the first current flow.

Integrated current sensors for a fuel cell stack

A fuel cell including a membrane electrode assembly composed of a ionically conductive member sandwiched between a pair of electrodes. At least one of the electrodes including a catalyst loading characterized by catalytic activity that varies in proportion to the catalyst loading. Moreover, the fuel cell includes a flow path for supplying gaseous reactants to the electrodes and the catalyst loading is varied according to the flow path geometry.

Variable catalyst loading based on flow field geometry

A measurement circuit that has particular application for detecting a high impedance measurement signal from a liquid water sensor. The measurement circuit includes a high impedance resistance-to-frequency conversion circuit that is coupled to the sensor and receives a resistance signal therefrom. The resistance-to-frequency conversion circuit includes an oscillator that converts the resistance signal to a representative frequency. The measurement circuit also includes a frequency-to-voltage conversion circuit that receives the frequency signal from the resistance-to-frequency conversion circuit, and converts the frequency signal to a representative voltage that provides an indication of water on the sensor.

Liquid water sensor signal conditioning circuit for use in PEM fuel cells

A fuel cell or electrochemical cell has a catalytic electrode and an electrically conductive contact element facing the electrode. The electrically conductive contact element conducts electrical current from the electrode and has a surface that includes a plurality of passivated regions and a plurality of non-passivated regions dispersed among the passivated regions. The surface is further coated with an electrically conductive, corrosion resistant coating. Methods include treating the electrically conductive contact element by passivation to resist corrosion while still maintaining electrical conductivity of the element.

Corrosion resistant plate for PEM fuel cell and methods of making same

A method for starting a frozen fuel cell stack includes discontinuing reactant humidification before shutting down the fuel cell stack. The anode and cathode are purged with the dry reactants. The fuel cell stack is soaked at freezing temperatures. During subsequent startup, dry reactants are initially delivered. An outlet temperature of the anode and a current load of the fuel cell stack are measured. The dry reactants are shut off when the temperature of the anode outlet or the current load reach predetermined values. The open circuit voltage potential of the fuel cells is monitored and compared to a first voltage value. When the open circuit voltage exceeds the first value, the fuel cell stack begins supplying current load. The current load of the fuel cell stack is increased or decreased based on a difference between the minimum voltage and a second voltage value.

Control system and method for starting a frozen fuel cell

The present invention relates to an electrochemical cell having a catalytic electrode and an electrically conductive contact element facing the electrode. The electrically conductive contact element conducts electrical current from the electrode and has a surface comprising a plurality of passivated regions, and a plurality of non-passivated regions dispersed among the passivated regions. The surface further is coated with an electrically conductive, corrosion resistant coating. Other preferred aspects of the present invention include methods of treating the electrically conductive contact element by passivation to resist corrosion while still maintaining electrical conductivity.

Corrosion resistant PEM fuel cell

A sensor plate for measuring current and/or temperature distribution of an operating fuel cell. The sensor plate has a circuit board interposed between an anode flow field plate and a cathode flow field plate of the fuel cell. A flow field plate is segmented into a plurality of electrically isolated regions without disrupting the flow field of the plate. The circuit board has an array of resistors and/or thermistors mounted to it wherein each resistor and/or thermistor is associated with one of the electrically isolated regions of the segmented plate. The current distribution of the electrically isolated regions of the fuel cell is calculated by using the voltage drop across the resistors and the known resistance values of the resistors mounted to the circuit board.

In-situ resistive current and temperature distribution circuit for a fuel cell

Recesses are located along an elongated elastomeric member. Electrical contacts are associated with the elastomeric member in registration with the recesses. The elastomeric member expands or compresses along its length to receive one of the closely spaced plates in each of the plurality of recesses and to thereby register the electrical contacts with a corresponding contact point on the plates. The elastomeric strip is confined under compression between two adjacent members which may be parts of two plates or of a single plate. The adjacent members define a recess, including locking protrusions, adapted to resist removal of the connector from within the retention recess unless the elongated elastomeric strip is compressed. An associated method optionally includes allowing the compressed elastomeric strip to push against adjacent members to generate a force which pushes the contact points against the one of the closely spaced plates.

Elongated elastomeric connector and method

A connector and method for electrically connecting to a series of closely spaced edges for use in monitoring individual cells using bipolar plates of a fuel cell stack. The connector includes an elongated elastomeric strip with electrical conductivity for a first side thereof to an opposing side thereof, but not having meaningful electrical conductivity in use along its elongated length. This elongate strip is held at an angle in relation to the closely spaced edges by alignment protrusions. This enables the use of a series of connectors which nest together to contact all the closely spaced edges. A plurality of electrically conductive elements are located on a printed circuit board against the opposing side of the elongated elastomeric strip in corresponding relationship to the closely spaced edges located against the first side of the elongate elastomeric strip. Means is provided for exerting a force to push the first side of the elongated elastomeric strip against the closely spaced edges is also provided.

Elastomeric connector for fuel cell stack cell voltage monitor

A PEM fuel cell is vacuum-dried before storing under freezing conditions.

Growing community of inventors

Spencerport, NY, United States of America

Robert L Fuss