Liquid fuel injector having dual nozzle outlet sets, fuel system, and method

A fuel system for an internal combustion engine comprising:

• a liquid fuel supply;
• a plurality of liquid fuel injectors each defining an inlet passage, a first set of nozzle outlets, a second set of nozzle outlets, and a low pressure space;
• the plurality of liquid fuel injectors each including a first direct-operated outlet check movable between a closed position blocking the first set of nozzle outlets, and an open position, and a second direct-operated outlet check movable between a closed position blocking the second set of nozzle outlets, and an open position;
• the plurality of liquid fuel injectors each further including a first injection control valve coupled with the first direct-operated outlet check, and a second injection control valve coupled with the second direct-operated outlet check;
• the first set of nozzle outlets in each one of the plurality of liquid fuel injectors forming a narrower spray angle, from about 130 degrees to about 140 degrees, and having a first combination of outlet number and outlet size, such that the first set of nozzle outlets produces a greater steady flow of fuel for injection;
• and
• the second set of nozzle outlets in each one of the plurality of liquid fuel injectors forming a wider spray angle, from about 140 degrees to about 150 degrees, and having a second combination of outlet number and outlet size different from the first combination, such that the second set of nozzle outlets produces a lesser steady flow of fuel for injection.

A method of operating an engine comprising:

• supplying a liquid fuel to a liquid fuel injector positioned at least partially within a cylinder in the engine;
• injecting a first charge of the liquid fuel into a cylinder in the engine using a first set of nozzle outlets in a fuel injector, such that spray jets of the first charge of liquid fuel are oriented at a relatively narrower spray angle;
• autoigniting the first charge of the liquid fuel such that the first charge of liquid fuel combusts by diffusion burning within the cylinder in a first engine cycle;
• injecting a second charge of the liquid fuel into the cylinder using a second set of nozzle outlets in the fuel injector such that spray jets of the second charge of the liquid fuel are oriented at a relatively wider spray angle;
• autoigniting the second charge of the liquid fuel such that the second charge of the liquid fuel combusts by diffusion burning within the cylinder in a second engine cycle;
• transitioning operation of the engine from a relatively higher engine load in the first engine cycle to a relatively lower engine load in the second engine cycle;
• decreasing fueling of the engine based on the transitioning of the operation of the engine, such that an amount of the second charge of the liquid fuel is smaller than an amount of the first charge of the liquid fuel;
• targeting, based on the relatively narrower spray angle, the first charge of liquid fuel at a first target in the cylinder relative to a piston, for entrainment of relatively less air;
• and
• targeting, based on the relatively wider spray angle, the second charge of liquid fuel at a second, different target in the cylinder relative to the piston, for entrainment of relatively more air.