Active Fuelling of a Passenger Car Sized Pre-Chamber Ignition System with Gaseous Components of Gasoline

Homogeneous lean or diluted combustion can significantly increase the efficiency of SI engines. Active fuelled pre-chamber ignition systems can overcome the problem that common spark ignitions systems are incapable to ignite strongly diluted mixtures. A small portion of the charge is burned in a separated chamber, which is connected to the main chamber by multiple small orifices. The combustion inside the pre-chamber generates hot gases, which penetrate into the main chamber and ignite the diluted charge on multiple sites. Pre-chamber ignition systems are named active when featuring a separate fuelling system in addition to the main combustion chamber. Gaseous fuel is preferable inside the pre-chamber looking at dosing accuracy and mixture preparation inside the pre-chamber. The usage of the mixture of air and gasoline fuel vapour present in the fuel tank above the liquid level to supply a gaseous fuel to the pre-chamber is one key aspect to develop an active pre-chamber ignition system for passenger cars. An experimental setup was built to simulate a fuel tank under different environmental conditions. The composition of the fuel vapour-air-mixture inside the tank was analysed using different industry known reference fuels for extreme conditions. The required concentration of hydrocarbons was reached with all tested fuels. The system was additionally integrated into a full engine testbench to analyse the engine combustion depending on the pre-chamber fuelling. The dosing of fuel vapour-air-mixture into the pre-chamber is implemented via a solenoid valve together with a self-developed check valve. With this system different versions of the pre-chamber were investigated. Investigations in the especially critical low-load range show stable engine combustion in all conditions while the dosed mass is adapted to the concentration of hydrocarbons in the gas phase.