Fuel Cells: Safety Regulations and Compliance

A recovery control system for fuel cells that can detect and recover from air supply issues that can occur when restarting the fuel cell after a shutdown. The system senses abnormal cell voltage behavior that indicates insufficient air supply. When this is detected after certain conditions are met, it increases the air flow to avoid cell performance degradation. The recovery system monitors voltage differences between measured and expected values. If the difference changes in a certain way after a power down, it indicates air supply issues and triggers increased airflow.

Techniques to control purging of fuel cells to remove accumulated gases and water at the anode, without excessive purging. The method involves periodically opening a purge valve when the fuel cell is at a lower pressure than its nominal operating pressure. The lower pressure is 70-95% of the nominal pressure. If the purge valve doesn't open within a maximum time, it could indicate a valve jam.

Fuel cell system design that protects hydrogen system components from damage due to loads like impacts. The design uses a layout where hydrogen system components are placed between the fuel cell stack and air system components. This ensures that if the fuel cell system receives a load, it is possible to suitably protect auxiliary devices which are present at positions where the pressure of the hydrogen gas is high. The upstream hydrogen auxiliary device is placed farther away from the air system component than the downstream hydrogen auxiliary device. This protects the upstream device from impacts.

Breather valve for hydrogen fuel cell vehicles with improved sealing to prevent leaks. The valve has a movable vent ring with an opening that connects to the transfer channel. A screw-coupled vent valve can close the opening. This allows pressure relief while maintaining a sealed connection between the valve body and vent valve to prevent fuel leaks.

Preventing accidental closing of fuel cell hydrogen injectors when starting power-hungry vehicle auxiliaries. A fuel cell vehicle has a hydrogen injector that opens when a current threshold is reached. The injector controller increases the current target when it detects start signals from high-power auxiliaries like AC. This prevents power dips from closing the injector prematurely. However, if a voltage converter supplies the injector, the target is not increased if converter output exceeds the main power supply.

Fault detection and response for hydrogen supply in a fuel cell system. The method uses pressure sensing and consumption estimation to diagnose issues like valve failure and leaks. It estimates hydrogen supply versus consumption and checks for abnormalities. Rapid pressure drops indicate valve failure. If supply-consumption mismatch exceeds a threshold, it detects a leak. Detected faults trigger corrective actions like entering an emergency mode, reducing load, or stopping the fuel cell for inspection.

Detecting low-level fuel injector leakage in a fuel cell system to prevent uncontrolled hydrogen release and fuel cell damage. The system monitors pressure in the anode gas loop, predicts expected pressure reduction during closed injector operation, and compares it to the actual reduction. If pressure decreases slower than expected, a leaky injector is indicated. Remedial actions include warning of the fault, reducing hydrogen from fuel lines, and preventing restart.

Optimizing control of a fuel cell's fuel electrode drain valve to prevent degradation and maintain hydrogen concentration in the exhaust at safe levels. The control system monitors hydrogen levels, pressures, and conditions to modulate the valve during condensate drainage and hydrogen purging. It opens fully for condensate to prevent stack damage, but adjusts for purging based on pressure differences to avoid excessive hydrogen release.

Fuel cell system design and control to manage temperature of the hydrogen pump exhaust gas. The system has a water pump to cool the hydrogen pump. The water pump is turned on or off based on the exhaust gas temperature. The water pump can be switched on when the exhaust gas is hot and switch off when it is cool. This optimizes cooling to prevent overheating while avoiding overcooling.

Hydrogen detection apparatus for fuel cell vehicles that optimizes energy savings versus reliability tradeoff by intermittently operating the hydrogen sensor with an off time that varies based on the operating environment. A microcomputer sets the off time and drives the sensor control circuit. The hydrogen sensor has exposed interfaces for contacting hydrogen gas. This allows environment-specific tuning of the detection frequency to save energy while still ensuring safety.

Process and system to mitigate overpressure in fuel cell anodes to prevent damage in the event of injector failure by detecting a stuck open injector and closing the hydrogen valve to prevent excess supply. The fuel cell stack continues to run and consume hydrogen to deplete the anode pressure. Other actions include opening the anode bleed valve, increasing cathode air pressure, and modulating load to maintain pressure balance.

Hydrogen filling system for fuel cell electric vehicles that prevents freezing of the fueling receptacle during fast hydrogen filling and overheating of the hydrogen tank. The system uses a buffer line connected between the fuel supply line and the fueling receptacle. Heat from compressed hydrogen flowing through the buffer line is used to warm the receptacle during filling, preventing freezing. A temperature sensor monitors the buffer line hydrogen temperature to detect tank overheating and avoids filling further.

Method for controlling fuel cell vehicles to prevent hydrogen backflow during purging and condensate discharge without adding check valves. When the fuel cell stack is off, the target purge and discharge levels are checked to determine if hydrogen will flow back from the air discharge line to the stack. If so, the target levels are adjusted to prevent backflow.

Method for controlling a fuel cell system that can diagnose whether hydrogen flows back into a stack enclosure during purging and condensate discharge, without the need to disassemble the stack enclosure and stack. The method involves detecting hydrogen inside the stack enclosure, stopping stack power generation if hydrogen is detected, purging hydrogen and discharging condensate, and then measuring hydrogen concentration inside the enclosure to determine if any backflow occurred.

Fuel cell system for a vehicle that prevents water ingress into the relief valve without using a casing or waterproof sheet. The relief valve in the fuel cell system is positioned above the fuel cell stack in the vehicle compartment with its exhaust port facing downwards. This prevents water from entering the relief valve since any liquid that comes into contact with the exhaust port will flow downwards away from the valve.