Fluid injector with auxiliary filling orifice

An internal combustion engine comprising:

• an engine housing defining a plurality of engine cylinders, and including a plurality of pistons each being movable within a corresponding one of the engine cylinders;
• and
• a fuel system including a plurality of fuel injectors associated one with each of the plurality of engine cylinders, each of the fuel injectors including an injector body defining a high pressure inlet, a fuel supply passage, a low pressure drain, and at least one tip orifice;
• a check needle movable within the fluid injector between a first position at which the check needle blocks the at least one nozzle outlet and a second position at which the check needle at least partially opens the at least one nozzle outlet, the check needle including at least one opening hydraulic surface exposed to a fluid pressure of the fuel supply passage and at least one closing hydraulic surface exposed to a fluid pressure of a check needle control chamber, wherein said check needle control chamber is in selective fluid communication with the low pressure drain via a first orifice, and said check needle control chamber is in fluid communication with the fuel supply passage via a second orifice, and said check needle control chamber is in selective fluid communication with the fuel supply passage via a third orifice, which is in parallel with the second orifice;
• and
• a control valve assembly having a valve member movable between a first position at which the low pressure drain is blocked to the check needle control chamber, and a second position at which the check needle control chamber is in fluid communication with the low pressure drain.

A method of operating a fuel injector having a check needle, comprising the steps of:

• supplying high pressure fuel to a nozzle chamber via a fuel supply passage;
• supplying high pressure fuel to a check needle control chamber via the fuel supply passage and a z-orifice;
• selectively supplying high pressure fuel to the check needle control chamber via the fuel supply passage and an f-orifice in parallel with the z-orifice,
• moving the check needle from a first position to a second position, wherein the check needle prevents fuel injection at the first position, and allows fuel injection at the second position;
• said moving step is accomplished by allowing fluid communication between the check needle control chamber and a low pressure drain via an a-orifice;
• and
• moving the check needle from the second position to the first position by blocking fluid communication between the check needle control chamber and the low pressure drain.