Electromagnetic fuel injector

An electromagnetic fuel injector having an energizable stator means for controlling the movement of a valve member of a valve assembly to open and close the injector and thereby meter fuel, said valve assembly comprising:

• a valve housing including a valve housing bore terminating with a valve seat which is connected to an exit orifice;
• a self-seating valve member including a cup-shaped armature means connected by a flexible stem member to a semispherical sealing surface, reciprocally located in said valve housing bore, and operable to obturate said exit orifice by sealing said valve seat with sealing surface;
• a closure spring mounted in said cup-shaped armature for producing a closure force to bias said semispherical sealing surface against said valve seat, said closure spring further maintaining an air gap between said armature and the stator means;
• first means for adjusting said air gap;
• second means for adjusting said closure force provided by said closure spring, said first and second means being complimentary and independently operable to calibrate static and dynamic fuel flow from said exit orifice;
• a swirl chamber having a volume being defined as the space between said semipherical sealing surface and said valve seat when the injector is closed and adapted to impart a swirl component to the fuel exhausted from the exit orifice when the injector is open and to retain a minimal residuum of fuel therein when the injector is closed;
• and
• means for supplying fuel from a pressurized source to said swirl chamber including at least one entry metering orifice positioned between said semispherical sealing surface and said valve seat for tangentially directing, with respect to the spray axis of the injector, a predetermined quantity of fuel into said exit orifice when said valve member and said valve seat are in an open relationship.

An electromagnetic fuel injector having an energizable stator means for controlling the movement of a valve member of a valve assembly to open and close the injector and thereby meter fuel, said valve assembly comprising:

• a valve housing including a valve housing bore terminating with a valve seat which is connected to an exit orifice;
• a self-seating valve member having an armature means connected by a flexible stem to a semispherical sealing surface, reciprocally located in said valve housing bore, and operable to obturate said exit orifice by sealing said valve seat with said sealing surface;
• an armature guide means on the stator means for slideably contacting said armature means during reciprocation;
• means for maintaining a predetermined air gap between said armature means and said armature guide means for maximizing the magnetic flux and minimizing the sliding resistance therebetween, said air gap means including a non-magnetic friction reducing material on one of said armature means and said armature guide means;
• a swirl chamber having a volume being defined as the space between said semipherical sealing surface and said valve seat when the injector is closed and adapted to impart a swirl component to the fuel exhausted from the exit orifice when the injector is open and to retain a minimal residuum of fuel therein when the injector is closed;
• and
• means for supplying fuel from a pressurized source to said swirl chamber including at least one entry metering orifice positioned proximate to the interface of said semispherical sealing surface and said valve seat for tangentially directing with respect to the spray axis of the injector a predetermined quantity of fuel into said exit orifice when said valve member and said valve seat are in an open relationship.