Rate shaping fuel injector with limited throttling

A closed needle injector assembly for injecting fuel into the combustion chamber of an engine, comprising:

• an injector body containing an injector cavity and only one set of injector orifices communicating with one end of said injector cavity to discharge fuel into the combustion chamber, said injector body including a fuel transfer circuit for transferring supply fuel to said only one set of injector orifices;
• an outer needle valve element positioned in said injector cavity, said outer needle valve element movable between a closed position against an outer valve seat blocking fuel flow across said outer valve seat and an open position permitting fuel flow across said outer valve seat;
• an inner needle valve element telescopingly received within a cavity formed in said outer needle valve element for controlling fuel flow through said only one set of injector orifices and an inner valve seat formed on said injector body, said inner valve element movable between a closed position against said inner valve seat blocking flow through said only one set of injector orifices and an open position permitting flow through said only one set of injector orifices;
• an outer supply cavity surrounding said outer needle valve element;
• an inner supply cavity positioned within said cavity formed in said outer needle valve element;
• a throttle passage extending through said outer needle valve element to fluidically connect said outer supply cavity and said inner supply cavity, said throttle passage sized to restrict fuel flow to said inner supply cavity.

A closed needle injector assembly for injecting fuel into the combustion chamber of an engine, comprising:

• an injector body containing an injector cavity and an injector orifice communicating with one end of said injector cavity to discharge fuel into the combustion chamber, said injector body including a fuel transfer circuit for transferring supply fuel to said injector orifice;
• a first needle valve element positioned in said injector cavity for controlling fuel flow through said injector orifice and a first valve seat formed on said injector body, said first needle valve element movable between a closed position against said first valve seat blocking flow through said injector orifice and an open position permitting flow through said injector orifice;
• a second needle valve element positioned in said injector cavity, said second valve element movable between a closed position against a second valve seat blocking fuel flow across said second valve seat and an open position permitting fuel flow across said second valve seat;
• a throttle passage formed in said second needle valve element to restrict fuel flow upstream of said injector orifice;
• a first control volume positioned adjacent an upper end of said first needle valve element for receiving fuel;
• a second control volume positioned adjacent an upper end of said second needle valve element for receiving fuel;
• an injection control valve means for controlling the flow of fuel from said first and said second control volumes;
• and
• a drain circuit for draining fuel from said first control volume and said second control volume to a low pressure drain, said injection control valve means further including a first injection control valve positioned along said drain circuit for controlling the flow of fuel through said drain circuit to control movement of said first needle valve element between said open and said closed positions and a second injection control valve positioned along said drain circuit for controlling the flow of fuel through said drain circuit to control movement of said second needle valve element between said open and said closed positions.

A closed needle injector assembly for injecting fuel into the combustion chamber of an engine, comprising:

• an injector body containing an injector cavity and an injector orifice communicating with one end of said injector cavity to discharge fuel into the combustion chamber, said injector body including a fuel transfer circuit for transferring supply fuel to said injector orifice;
• a first needle valve element positioned in said injector cavity for controlling fuel flow through said injector orifice and a first valve seat formed on said injector body, said first needle valve element movable between a closed position against said first valve seat blocking flow through said injector orifice and an open position permitting flow through said injector orifice;
• a second needle valve element positioned in said injector cavity, said second valve element movable between a closed position against a second valve seat blocking fuel flow across said second valve seat and an open position permitting fuel flow across said second valve seat;
• a throttle passage formed in said second needle valve element to restrict fuel flow upstream of said injector orifice;
• a first control volume positioned adjacent an upper end of said first needle valve element for receiving fuel;
• a second control volume positioned adjacent an upper end of said second needle valve element for receiving fuel;
• an injection control valve means for controlling the flow of fuel from said first and said second control volumes;
• and
• an outer cavity surrounding said second needle valve element and an inner supply cavity formed within said second needle valve element, further including a lift control means positioned within said inner supply cavity for controlling the movement of said second needle valve element from said closed position.

A closed needle injector assembly for injecting fuel into the combustion chamber of an engine, comprising:

• an injector body containing an injector cavity and an injector orifice communicating with one end of said injector cavity to discharge fuel into the combustion chamber, said injector body including a fuel transfer circuit for transferring supply fuel to said injector orifice;
• an outer needle valve element positioned in said injector cavity, said second valve element movable between a closed position against an outer valve seat blocking fuel flow across said outer valve seat and an open position permitting fuel flow across said outer valve seat;
• an inner needle valve element telescopingly received within a cavity formed in said outer needle valve element for controlling fuel flow through said injector orifice and an inner valve seat formed on said injector body, said inner valve element movable between a closed position against said inner valve seat blocking flow through said injector orifice and an open position permitting flow through said injector orifice;
• an outer supply cavity surrounding said outer needle valve element;
• an inner supply cavity positioned within said cavity formed in said outer needle valve element;
• a throttle passage extending through said outer needle valve element to fluidically connect said outer supply cavity and said inner supply cavity, said throttle passage sized to restrict fuel flow to said inner supply cavity;
• and
• a drain circuit for draining fuel from said inner and said outer control volumes to a low pressure drain, said injection control valve means further including an outer injection control valve positioned along a drain circuit for controlling the flow of fuel through said drain circuit to control movement of said outer needle valve element between said open and said closed positions and an inner injection control valve positioned along said drain circuit for controlling the flow of fuel through said drain circuit to control movement of said inner needle valve element between said open and said closed positions.

A closed needle injector assembly for injecting fuel into the combustion chamber of an engine, comprising:

• an injector body containing an injector cavity and an injector orifice communicating with one end of said injector cavity to discharge fuel into the combustion chamber, said injector body including a fuel transfer circuit for transferring supply fuel to said injector orifice;
• an outer needle valve element positioned in said injector cavity, said second valve element movable between a closed position against an outer valve seat blocking fuel flow across said outer valve seat and an open position permitting fuel flow across said outer valve seat;
• an inner needle valve element telescopingly received within a cavity formed in said outer needle valve element for controlling fuel flow through said injector orifice and an inner valve seat formed on said injector body, said inner valve element movable between a closed position against said inner valve seat blocking flow through said injector orifice and an open position permitting flow through said injector orifice;
• an outer supply cavity surrounding said outer needle valve element;
• an inner supply cavity positioned within said cavity formed in said outer needle valve element;
• a throttle passage extending through said outer needle valve element to fluidically connect said outer supply cavity and said inner supply cavity, said throttle passage sized to restrict fuel flow to said inner supply cavity;
• and
• a lift control means positioned within said inner supply cavity for controlling the movement of said outer needle valve element from said closed position.

A closed needle injector assembly for injecting fuel into the combustion chamber of an engine, comprising:

• an injector body containing an injector cavity and an injector orifice communicating with one end of said injector cavity to discharge fuel into the combustion chamber, said injector body including a fuel transfer circuit for transferring supply fuel to said injector orifice;
• a first needle valve element positioned in said injector cavity for controlling fuel flow through said injector orifice and a first valve seat formed on said injector body, said first needle valve element movable between a closed position against said first valve seat blocking flow through said injector orifice and an open position permitting flow through said injector orifice;
• a second needle valve element positioned in said injector cavity, said second valve element movable between a closed position against a second valve seat blocking fuel flow across said second valve seat and an open position permitting fuel flow across said second valve seat;
• a throttle passage formed in said second needle valve element to restrict fuel flow upstream of said injector orifice;
• a first control volume positioned adjacent an upper end of said first needle valve element for receiving fuel;
• a second control volume positioned adjacent an upper end of said second needle valve element for receiving fuel;
• an injection control valve means for controlling the flow of fuel from said first and said second control volumes;
• and
• a first biasing spring for biasing said first needle valve element toward said closed position and a second biasing spring for biasing said second needle valve element toward said closed position.

A closed needle injector assembly for injecting fuel into the combustion chamber of an engine, comprising:

• an injector body containing an injector cavity and an injector orifice communicating with one end of said injector cavity to discharge fuel into the combustion chamber, said injector body including a fuel transfer circuit for transferring supply fuel to said injector orifice;
• a first needle valve element positioned in said injector cavity for controlling fuel flow through said injector orifice and a first valve seat formed on said injector body, said first needle valve element movable between a closed position against said first valve seat blocking flow through said injector orifice and an open position permitting flow through said injector orifice;
• a second needle valve element positioned in said injector cavity, said second valve element movable between a closed position against a second valve seat blocking fuel flow across said second valve seat and an open position permitting fuel flow across said second valve seat;
• a throttle passage formed in said second needle valve element to restrict fuel flow upstream of said injector orifice;
• a first control volume positioned adjacent an upper end of said first needle valve element for receiving fuel;
• a second control volume positioned adjacent an upper end of said second needle valve element for receiving fuel, said second control volume positioned adjacent said first control volume along an axial extent of the injector;
• and
• an injection control valve means for controlling the flow of fuel from said first and said second control volumes.