Method of operating an engine having a pilot subchamber at partial load conditions

A method of operating an internal combustion engine having a number P of pilot subchambers communicating with main combustion chambers, the internal combustion engine configured in use to deliver a main fuel injection of a maximum quantity of fuel to the main combustion chambers when the internal combustion engine is operated at maximum load, the method comprising:

• delivering a pilot fuel injection of a pilot quantity of fuel to the pilot subchambers, the pilot quantity being at most 10% of the maximum quantity;
• igniting the pilot fuel injection of the pilot quantity of fuel within the pilot subchambers;
• directing the ignited fuel from the pilot subchambers to the main combustion chambers;
• for a number n of the main combustion chambers receiving the ignited fuel, delivering a main fuel injection of a first main quantity of fuel, the first main quantity being at most 10% of the maximum quantity;
• for a number P-n of the main combustion chambers receiving the ignited fuel, delivering a main fuel injection of a second main quantity of fuel, the second main quantity of fuel being more than 10% of the maximum quantity;
• and varying n between zero and P.

A method of operating a rotary internal combustion engine including a rotor sealingly received in a housing to define a plurality of rotating main combustion chambers, the rotary internal combustion engine configured in use to deliver a main fuel injection of a maximum quantity of fuel to the main combustion chambers when the internal combustion engine is operated at maximum load, the method comprising:

• delivering a pilot fuel injection of a pilot quantity of fuel to the pilot subchamber, the pilot quantity being at most 10% of the maximum quantity;
• igniting the pilot fuel injection of the pilot quantity of fuel within the pilot subchamber;
• directing the ignited fuel from the pilot subchamber into one of the main combustion chambers;
• and
• delivering a main fuel injection of a main quantity of fuel to the main combustion chamber receiving the ignited fuel, the main quantity being at most 10% of the maximum quantity.