Fuel system

A method of delivering fuel to an internal combustion engine provided with an after treatment device for reducing emission levels, the method comprising;

• driving a pumping plunger to perform a pumping stroke of a pumping cycle, thereby to pressurise fuel within the pumping chamber to a high level, following which the pumping plunger performs a return stroke of the pumping cycle;
• delivering high pressure fuel to an injector associated with the engine through a high pressure line;
• controlling an injection control valve arrangement to move between an open state to commence a main fuel injection event and a closed state to terminate the main fuel injection event, during which main fuel injection event a main fuel injection quantity is delivered to the engine;
• and
• moving the injection control valve arrangement from the closed state to the open state to permit a late post fuel injection quantity to be delivered to the engine, within the pumping cycle and a period of time after the main fuel injection event, for the purpose of regeneration of the after treatment device;
• whereby the late post injection quantity is delivered after completion of the pumping stroke.

A method of delivering fuel to an internal combustion engine provided with an after treatment device for reducing emission levels, the method comprising:

• driving a pumping plunger to perform a pumping stroke of a pumping cycle, thereby to pressurise fuel within the pumping chamber to a high level, following which the pumping plunger performs a return stroke of the pumping cycle;
• delivering high pressure fuel to an injector associated with the engine through a high pressure line;
• controlling an injection control valve arrangement to move between an open state to commence a main fuel injection event and a closed state to terminate the main fuel injection event, during which main fuel injection event a main fuel injection quantity is delivered to the engine;
• moving the injection control valve arrangement from the closed state to the open state to permit a late post fuel injection quantity to be delivered to the engine, within the pumping cycle and a period of time after the main fuel injection event, for the purpose of regeneration of the after treatment device;
• and
• providing a sequence of around 3 to 5 consecutive main fuel injection events, each of which is accompanied by a late post fuel injection event.

A method of delivering fuel to an internal combustion engine provided with an after treatment device for reducing emission levels, the method comprising:

• driving a pumping plunger to perform a pumping stroke of a pumping cycle, thereby to pressurise fuel within the pumping chamber to a high level, following which the pumping plunger performs a return stroke of the pumping cycle;
• delivering high pressure fuel to an injector associated with the engine through a high pressure line;
• controlling an injection control valve arrangement to move between an open state to commence a main fuel injection event and a closed state to terminate the main fuel injection event, during which main fuel injection event a main fuel injection quantity is delivered to the engine;
• moving the injection control valve arrangement from the closed state to the open state to permit a late post fuel injection quantity to be delivered to the engine, within the pumping cycle and a period of time after the main fuel injection event, for the purpose of regeneration of the after treatment device;
• and
• providing a periodic distribution of late post injection events between main fuel injection events.

A fuel system for use in an internal combustion engine, the fuel system comprising;

• a fuel pump having a pumping cycle during which fuel is pressurised to a high level within a pumping chamber for delivery to an injector, whereby the injector is arranged to provide a main fuel injection event and a post fuel injection event, during within the same pumping cycle;
• the injector including a valve needle which is engageable with a valve needle seating to control said fuel delivery and an injection control valve arrangement for controlling movement of the valve needle so as to control the main and post fuel injection events;
• and,
• the fuel system further comprising an accumulator volume for storing high pressure fuel for delivering the post fuel injection quantity, and an additional valve arrangement actuable to control the supply of fuel stored within the accumulator volume to the injector for the post injection event, wherein the additional valve arrangement and the injection control valve arrangement share a common actuator.