An electromagnetically operable fuel injector for a fuel injection system of an internal combustion engine, the injector having a generally longitudinal axis, and including a ferromagnetic core, a magnetic coil at least partially surrounding the ferromagnetic core, and an armature magnetically coupled to the magnetic coil and being movably responsive to the magnetic coil. The armature is adapted to actuate a valve closing element interactive with a fixed valve seat and being movable away from the fixed valve seat when the magnetic coil is excited. The armature has a generally cylindrical shape and a generally central opening defining a through-passage for reception of fuel from a fuel inlet connector positioned adjacent thereto. A valve-closing element is attached to the armature and is positioned to be selectively moved toward and away from the fixed valve seat. The valve closing element is in the form of an elongated valve needle having a generally central shaft portion and a generally cylindrical end portion, the generally cylindrical end portion having a diameter greater than the generally central shaft portion and a sealing end surface having a spherical shape. Although gaseous fuels such as compressed natural gas are primarily contemplated, the invention is applicable for use with liquid fuels.
CROSS-REFERENCE TO RELATED APPLICATION
This application expressly claims the benefit of earlier filing date and right of priority from the following co-pending patent applications: U.S. Provisional Application U.S. Ser. No. 60/086,937, entitled "Contaminant Tolerant Compressed Natural Gas Injector" filed May 27, 1998; and U.S. Provisional Application U.S. Ser. No. 60/086,939, entitled "Needle Valve For Low Noise Fuel Injector" filed May 27, 1998. Both cited provisional patent applications are expressly incorporated in their entirety by reference.
A compressed natural gas fuel injector including a housing, an inlet, an outlet, a seat, a closure member, and an attached nozzle. In a preferred embodiment, the inlet and outlet communicate a flow of gaseous fuel regulated by the closure member. The gaseous fuel passes through the seat, which is coupled to a rim surface of a retainer portion of the attached nozzle, and into a flow passage that further communicates the flow of gaseous fuel into one or more flow channels. The orientation of the flow channels within the attached nozzle greatly affects the discharge pattern and mixing characteristics of the gaseous fuel within an intake manifold. A method of flowing gaseous fuel through the fuel injector is also described.
A nozzle for delivering fuel to an engine is disclosed which is profiled with adjoining converging and diverging sections to accelerate the flow of fuel to a supersonic rate.
An electromagnetically actuable fuel injector for an internal combustion engine is disclosed having an outer housing, a fuel inlet connector positioned in the upper end portion of the outer housing for reception of fuel therein, and an armature having a valve needle attached thereto and positioned adjacent the fuel inlet connector and spaced therefrom by a working gap. The armature defines a generally elongated central opening to receive fuel flow from the fuel inlet connector and has valve needle attached thereto which interacts with a fixed valve having a fixed valve seat associated with the housing to selectively permit fuel to flow through a valve aperture associated with the fixed valve seat. The fuel inlet connector has a fuel outlet end facing a fuel inlet end of the armature and includes a plurality of radially extending raised pads separated by a corresponding plurality of radially extending recessed portions to reduce the contact area between the fuel inlet connector and the armature when the armature is moved upwardly, and to promote fuel flow transversely across the working gap therebetween to establish a first fuel flow path outside of the armature. The first fuel flow path prevents contaminants from accumulating in the working gap. The armature includes at least one first aperture extending through a wall portion thereof for receiving fuel flow from the generally elongated central opening and for directing the fuel flow to a second flow path toward the fixed valve seat. At least one-second aperture extends through a wall portion of the armature and extends at a generally acute angle relative to the longitudinal axis to establish a third fuel flow path toward the fixed valve seat. The size, orientation and numbers of the apertures can be varied to achieve predetermined flow conditions. A method of directing fuel through an injector is also disclosed although the fuel injector and method disclosed utilize gaseous fuels, all types of fuels are contemplated.
This invention relates to the injection of compressible gaseous fuel directly into the combustion chamber of a reciprocating piston-type internal combustion engine. In particular, the invention provides apparatus and methods for low-pressure, high-speed direct injection of compressed natural gas into a combustion chamber of an engine. Using the present invention, relatively low intake pressures of about 50 to about 150 PSIG yield high-speed (sonic and supersonic) gas flow through the diverging nozzle portion for injection into the combustion chamber. Preferably, the gas reaches supersonic velocity, approaching Mach 1.5 to 2.5.
