Air assist fuel injector with fuel swirl feature

Details Air assist fuel injector with fuel swirl feature Air assist fuel injector with fuel swirl feature

1999-01-13

2001-03-27

Solis, Erick (Department: 3747)

Internal-combustion engines

Charge forming device

Auxiliary air or gas used to inject fuel

C123S585000, C239S403000, C239S533140

Reexamination Certificate

active

06205983

ABSTRACT:

FIELD OF THE INVENTION
This invention relates to fuel injectors for spark-ignition, internal combustion engines and, more particularly, to an air assist fuel injector in which a turbulent swirling fuel stream is created and atomized, and which provides a well defined targeted spray of an air-fuel mixture.
BACKGROUND OF THE INVENTION
The advent of internal combustion engines having multiple intake valves combined with government regulations for ultra-low emission vehicles has developed a need for highly defined spray targeting of very small fuel particles.
Air assist fuel injectors have been developed that provide enhanced atomization so that exhaust emissions can be minimized through more complete combustion. Such injectors also provide a well-defined spray pattern for targeting engine intake valves.
Although these air assist injectors improve fuel atomization and fuel spray targeting, the need for improved fuel injectors providing improved fuel atomization and spray targeting continues to exist.
SUMMARY OF THE INVENTION
The present invention provides an air assist fuel injector that directs a plurality of fuel streams inwardly toward a swirl chamber where the fuel streams converge and form a turbulent swirling fuel stream directed axially outwardly past the needle valve of the injector. The swirling fuel stream readily atomizes and is carried by assist air providing a mixture having a very small particle size that is distributed as a well defined targeted spray.
The invention provides a fuel injector for a spark-ignition, internal combustion engine including a fuel injector body having inlet and discharge ends. The discharge end includes a fuel swirl disk for inwardly directing a plurality of fuel streams to provide a turbulent swirling stream of fuel directed axially outwardly. A valve element regulates the outward axial flow of the turbulent swirling fuel stream.
A mixing chamber having an air supply provides a flow of assist air and a discharge passageway. The mixing chamber receives the turbulent swirling fuel stream which is atomized as it enters the mixing chamber and the atomized fuel mixed with the assist air is directed outwardly through the discharge passageway.
According to the invention, the swirl disk includes a plurality of annularly spaced fuel inlet passages connected by fuel flow passageways to a centrally located swirl chamber. The plurality of fuel flow passageways extend from the inlet passages and tangentially connect with the centrally located swirl chamber. Fuel flowing inward through the flow passageways is swirled in the centrally located swirl chamber and then discharged axially.
In one embodiment of the invention, the fuel swirl disk includes six radially spaced fuel inlet passages and six fuel flow passageways.
The mixing chamber air supply provides an inwardly directed flow of assist air which carries the atomized fuel stream outwardly through the discharge passageway. An orifice plate may be interposed between the swirl disk and mixing chamber for throttling the turbulent swirling fuel stream into the mixing chamber, thereby improving fuel atomization provided by the pressure drop across the orifice.
In an exemplary embodiment, an air shroud encloses the mixing chamber. Axially disposed spray shaping passages are in communication with the mixing chamber discharge passageway for providing an atomized fuel spray distribution through the passages.
In an application where the injector is used with an internal combustion engine having cylinders with two intake valves, the shroud includes two spray shaping passages for providing a targeted split stream spray pattern therein.
These and other features and advantages of the invention will be more fully understood from the following detailed description of the invention taken together with the accompanying drawings.


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