B - Components of Fuel Systems Across Vehicle Technologies

Components of Fuel Systems Across Vehicle Technologies

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Fuel System Component: Purge Valve and Water Drain Valve

• These components are responsible for removing excess water and non-hydrogen contents, maximizing system efficiency.

Fuel System Component: Mechanical Dump Valve (MDV)

• Many common rail diesel fuel systems have a mechanical dump valve (MDV) located in the fuel rail.
• The MDV is a spring-loaded valve that is forced open when fuel pressure exceeds a pre-set limit. It acts as a safety device to release pressure if it exceeds safe limits protecting the fuel system components from damage.
• Some diesel engines even possess electronic dump valves which can be used for improved fuel pressure control.

Fuel System Component: Filtration

• In diesel engines, advanced filtration technology removes debris and water from the fuel before it gets to the fuel injectors. Contaminants in the fuel can significantly affect engine performance and longevity due to the extreme fuel pressures and fine nozzle holes on injectors.
• In natural gas and hydrogen ICE vehicles, filtration cleans the fuel and removes compressor oils. This is critical for the performance and longevity of the engine as compressor oils can adversely affect the fuel system, especially in trucks powered by natural gas.

Fuel System Component: Fuel Pumps

• Diesel engines commonly use multiple fuel pumps. The low-pressure pump pulls fuel from the tank and delivers it to the high-pressure pump.
• The high-pressure pump then pressurizes and regulates fuel flow to the injectors. It is a critical component in achieving the required injection pressure for efficient combustion.
• In commercial trucks, pumps ensure optimal fuel delivery in the most demanding driving conditions.

Fuel System Component: Hydrogen Recirculation Pump

• Working in conjunction with the ejector, this pump recirculates unused hydrogen from the fuel cell stack back into the system.

Fuel System Component: Plumbing

• Both metallic and non-metallic fuel lines seal and transfer fuel throughout the fuel system in diesel engines.
• Appropriately sized fuel plumbing is critical for meeting engine application demands and preventing leaks.
• In commercial vehicles, robust plumbing is essential to withstand the rigors of long-distance travel and various operating conditions.

Fuel System Component: Pressure Relief Valve

• This is a safety device that protects the fuel cell stack in fuel cell vehicles from excessive fuel pressure. It is a critical component in all hydrogen fuel cell vehicles for safe operations under all conditions.

The Fuel System

• The fuel system is part of the powertrain and includes all components necessary for regulating fuel delivery to the engine. This includes: the fuel tank, pump, filter, injectors and sensors.
• The fuel delivery system and its components are a subset of the fuel system, specifically focusing on components directly involved in delivering fuel from the tank to the engine.
• Natural gas and hydrogen internal combustion engines (ICE) fit the same architecture as a diesel engine, requiring less change to the vehicle.
• Gaseous fuel systems have fewer components than an equivalent diesel fuel system but are still critical to delivering optimal performance and meeting stricter emissions.

Fuel System Component: On-Engine Shut Off Valve/Pressure Regulator

• In natural gas and hydrogen engines, on-engine pressure regulators may be used to regulate the fuel pressure delivered to the injectors. This ensures accurate fueling at any engine operating condition.
• Shut-off valves may also be integrated into the regulator. These valves prevent fuel flow to the engine when the vehicle is shut off.
• In fuel cell vehicles, this valve allows fuel flow into the injector and acts as an on/off valve that closes when the engine is shut off.

Fuel System Component: Fuel Rail

• The fuel rail is a manifold responsible for distributing fuel to the injectors and ensuring efficient delivery of fuel across all engine cylinders.
• It enables the fuel system to deliver the optimal fuel pressure across a range of engine operating conditions, which is crucial for consistent engine performance and emissions reductions.

Fuel System Component: Fuel Injectors/ Proportion Control Valve

• Diesel and gaseous fuel injectors ensure correct amounts of fuel into the combustion.
• In diesel engines, fuel injectors deliver precise amounts of fuel with spray patterns that ensure optimal mixing of fuel and air. This precision is vital for efficient combustion, maximizing fuel efficiency and reducing emissions.
• In hydrogen ICE vehicles, the injector is designed to handle the unique properties of hydrogen while still meeting engine performance demands.
• Fuel cell vehicles may opt for either an injector or proportional control valve to regulate the flow of hydrogen to the fuel cell stack. It ensures the precise amount of hydrogen is delivered to react with oxygen and generate electricity which provides power to the vehicle.

Fuel System Component: Ejectors

• Ejectors in fuel cell vehicles help to recirculate unused hydrogen back to the fuel cell stack. This is critical for increasing efficiency and ensuring durability of the fuel cell.

Fuel System Component: Pressure Sensor

• The pressure sensor located in the fuel rail measures the fuel pressure and communicates with the engine control unit (ECU) to fire the injectors long enough to deliver the correct amount of fuel.
• The fuel pressure sensor can also detect issues with the fuel system such as leaks. Maintaining the appropriate fuel pressure is critical for maintaining engine integrity and performance.