Fuel injector having dry-running protection valve and fuel system using same

An engine head assembly comprising:

• an engine head having an injector bore formed therein;
• a fuel injector within the injector bore and including an injector housing defining a longitudinal axis and having formed therein an actuation fluid inlet and an actuation fluid outlet, and including a nozzle having formed therein a nozzle supply passage and a plurality of spray outlets;
• a check control valve assembly within the injector housing;
• a direct-operated check movable between a closed position blocking the plurality of spray outlets from the nozzle supply passage, and an open position;
• a valve biaser within the injector bore, the valve biaser being located outside of the injector housing between the injector housing and the engine head and supported on an outer surface of the injector housing exposed to the injector bore and having the actuation fluid outlet formed therein;
• and
• a dry-running protection valve trapped between the valve biaser and the injector housing and movable, in opposition to a biasing force of the valve biaser, from a closed position blocking the actuation fluid outlet to an open position.

A method of operating a fuel system for an engine comprising:

• operating check control valve assemblies in each of a plurality of fuel injectors in the fuel system to open and close outlet checks in the plurality of fuel injectors;
• draining actuation fluid from check control chambers in the plurality of fuel injectors based on the operation of the check control valve assemblies;
• limiting expelling the drained actuation fluid through an actuation fluid outlet in each respective one of the plurality of fuel injectors with dry-running protection valves of each of the plurality of fuel injectors;
• filling low-pressure volumes in each of the plurality of fuel injectors with the drained actuation fluid in advance of filling a low pressure return conduit common to the plurality of fuel injectors, based on the limiting of the expelling of the drained actuation fluid;
• expelling actuation fluid through the actuation fluid outlets, based on operation of the check control valve assemblies, after the filling of the low-pressure volumes in each of the plurality of fuel injectors;
• and
• the expelling actuation fluid in each respective fuel injector further including expelling the actuation fluid in opposition to a bias of a valve biaser within an injector bore between an outer surface of an injector housing and an engine head.