Menetelmä polttomoottorin käyttämiseksi

The invention relates to a method of operating an internal combustion engine by combusting gaseous fuel comprising the steps of feeding gaseous fuel and combustion air to the combustion chamber of the engine, compressing the mixture of the combustion air and the gaseous fuel in the combustion chamber, feeding the mixture of the combustion air and the gaseous fuel from the combustion chamber to a first and a second pre-chamber arranged in flow communication with the combustion chamber, igniting the mixture of the combustion air and the gaseous fuel in the first pre-chamber at a first moment, and igniting said mixture in the second pre-chamber at a second moment, after the first moment, ignition being accomplished by means of injecting liquid fuel into a pre-chamber and igniting the liquid fuel by compression ignition.