|
Fuel systems are designed in such a way that the fuel circulates from the fuel cap to the engine and is used in the vehicle in safe conditions and with a minimum impact on the environment. Fuel systems are complex structures made of various elements, each of them playing a specific role in controlling the fuel's movements and emissions in the vehicle, and also reducing the fire hazards which are linked to the use of fuel.
At the gas station, for instance, some of these elements work together in optimizing the conditions for filling, such as:
-
A ground connection in order to avoid electrostatic discharge (ESD) when the fuel nozzle gets in contact with the filler pipe;
-
Breathing lines, liquid separators and canisters in order to evacuate the vapours that are replaced by the liquid in the fuel tank and to avoid their release in the atmosphere;
-
Fuel limit vents, anti-spit back valves, and inlet check valves in order to avoid premature shut-off, i.e. when the fuel nozzle shuts off before the fuel tank is actually full, which happens if the architecture of the filling pipe is not optimized;
-
Over-filling prevention valves in order to avoid exceeding the capacity of the fuel tank; and
-
Anti-spit back valves which prevent the back flow of the fuel into the filler pipe and spill over.
Once the fuel has gone through the filling pipe it goes into the fuel tank where it is stored. Adequate solutions also have to be found for the storage of fuel in terms of safety, weight, noise reduction and economical requirements. Plastics is the material that answers best these requirements (see Benefits of Plastic Fuel Tanks).
Fixations to the car chassis, straps and inserts not only help keeping the fuel tank in place but also preserving its shape in all driving conditions.
Besides the fuel limit vents, other venting devices like the over pressure release valve are included in the fuel system in order to control vapour emissions and pressure in the fuel tank and to avoid releases in the atmosphere. In the case of a car roll-over, the roll-over valve closes the venting system in order to avoid fuel leakage on the road.
Fuel systems also play a role in gauging the level of fuel contained in the fuel tank. A gauge is mounted inside the tank and is connected to electronic devices which translate the gauge's signal into a fuel level shown on the dashboard. The gauge and related electronic devices are very often mounted onto the fuel delivery module.
The fuel delivery module also integrates the pump, the filter and the pressure regulator. These elements play a role in feeding the engine with the appropriate amount of fuel with the right pressure. The fuel that is injected into the engine passes through feeding lines. Very often not all the amount of fuel that has been injected is used by the engine. Therefore the fuel that has not been burned returns to the tank through return lines. However, these return lines tend to disappear, as new systems are being developed to permit the delivery of fuel on demand. | 
