Fluid sprinkling – spraying – and diffusing – Including valve means in flow line – Reciprocating
Reexamination Certificate
1999-05-26
2001-12-11
Kashnikow, Andres (Department: 3752)
Fluid sprinkling, spraying, and diffusing
Including valve means in flow line
Reciprocating
C239S590300
Reexamination Certificate
active
06328231
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present application relates to a compressed natural gas injector, which incorporates an improved low noise valve needle.
2. Description of the Related Art
Compressed natural gas (hereinafter sometimes referred to as “CNG”) is becoming a common automotive fuel for commercial fleet vehicles and residential customers. In vehicles, the CNG is delivered to the engine in precise amounts through gas injectors, hereinafter referred to as “CNG injectors”. The CNG injector is required to deliver a precise amount of fuel per injection pulse and maintain this accuracy over the life of the injector. In order to maintain this level of performance for a CNG injector, certain strategies are required to help reduce the effects of contaminants in the fuel.
Compressed natural gas is delivered throughout the country in a pipeline system and is mainly used for commercial and residential heating. While the heating systems can tolerate varying levels of quality and contaminants in the CNG, the tolerance levels in automotive gas injectors are significantly lower.
These contaminants, which have been acceptable for many years in CNG used for heating, affect the performance of the injectors to varying levels and will need to be considered in future CNG injector designs. Some of the contaminants found in CNG are small solid particles, water, and compressor oil. Each of these contaminants needs to be addressed in the injector design for the performance to be maintained over the life of the injector.
The contaminants can enter the pipeline from several sources. Repair, maintenance and new construction to the pipeline system can introduce many foreign particles into the fuel. Water, dust, humidity and dirt can be introduced in small quantities with ease during any of these operations. Oxides of many of the metal types found in the pipeline can also be introduced into the system. In addition, faulty compressors can introduce vaporized compressor oils, which blow by the seals of the compressor and enter into the gas. Even refueling can force contaminants on either of the refueling fittings into the storage cylinder. Many of these contaminants are likely to reach vital fuel system components and alter the performance characteristics over the life of the vehicle.
In addition to contaminants in the CNG, presently known valve components of fuel injectors have been known to present certain disadvantages, when used with CNG as well as with liquid fuels. For example, the armature and valve needle of a typically known injector produces distinguishable sounds upon opening of the valve and on closing of the valve. In particular, the force of impact, which is equal to the valve component mass multiplied by acceleration, can generate sounds within an engine compartment, which are generally perceived as either a mechanical problem or otherwise harsh and objectionable noise.
In general, fuel injectors require extremely tight tolerances on many of the internal components to accurately meter the fuel. For CNG injectors to remain contaminant tolerant, the guide and impact surfaces for the armature needle assembly require certain specifically unique characteristics. Also, the valve needles are difficult to control precisely, given the specific environment provided by the CNG. We have invented a CNG fuel injector which represents a significant improvement over presently known injectors which incorporates an improved valve needle having reduced needle mass and providing low noise on closing.
SUMMARY OF THE INVENTION
The invention relates to an electromagnetically operable fuel injector for a fuel injection system of an internal combustion engine, the injector having a generally longitudinal axis, which comprises, a ferromagnetic core, a magnetic coil at least partially surrounding the ferromagnetic core, an armature magnetically coupled to the magnetic coil and being movably responsive to the magnetic coil, the armature being 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 elongated shape and a generally central opening for axial reception of fuel from a fuel inlet connector positioned adjacent thereto. A valve closing element is attached to the armature and positioned to be selectively moved toward and away from a generally frusto-conically shaped fixed valve seat, the valve closing element being an elongated valve needle having a generally central shaft portion and a generally cylindrical end portion. The generally cylindrical end portion of the valve needle has a diameter greater than the generally central shaft portion, and having a generally spherical end surface for sealing engagement with the fixed valve seat.
Preferably the fuel inlet connector extends in a generally longitudinal direction above the armature and defines a path for fuel to enter the inlet connector and to be directed toward the armature, the fuel inlet connector having a lowermost surface spaced above the armature to define a working gap through which the armature is movable. The armature has a fuel reception portion for receiving fuel directed from the fuel inlet connector and directing the fuel toward the fixed valve seat for entry into an intake manifold of the engine. The fuel inlet connector and the armature are adapted to permit a first flow path of gaseous fuel between the armature, the magnetic coil, and a valve body shell as part of a path leading to the fuel valve. The armature defines at least one first fuel flow aperture extending through a wall portion thereof to define a second flow path of gaseous fuel as part of a path leading to the fuel valve. The armature defines at least one-second aperture in a wall portion thereof to define a third flow path of gaseous fuel as part of a path leading to the fuel valve. The at least one second aperture is oriented at a generally acute angle with respect to the longitudinal axis.
The fuel injector further comprises a valve body positioned downstream of the armature and having at least one aperture in a wall portion thereof for reception of fuel from at least two of the flow paths of gaseous fuel from the armature and the fuel inlet connector. The fuel inlet connector is positioned above the armature and is spaced from the armature by the working gap, the fuel inlet connector defining a through passage for directing fuel toward the armature and the fixed valve seat. The fuel inlet connector comprises an upper end portion adapted for reception of gaseous fuel from a fuel source, and a lower end portion for discharging gaseous fuel, the lower end portion having a lower surface which faces an upper surface of the armature, the lower surface of the fuel inlet connector having a plurality of radially extending raised pads defined thereon, the pads having recessed portions therebetween to permit fuel to flow therethrough and across the working gap defined between the fuel inlet connector and the armature. The generally cylindrical end portion of the valve needle has a generous radius at the lower end portion thereof for engagement with a correspondingly shaped surface of the valve seat. The valve needle is attached to said armature by crimped portions, and the correspondingly shaped surface of the valve seat preferably has a generally frust-oconical cross-sectional shape. The fuel inlet connector further includes a fuel filter at an upper end portion thereof for filtering fuel.
The valve needle is a generally elongated valve needle having a spherically shaped end portion and configured and adapted to engage a frusto-conically shaped surface of the fixed valve seat to closed the valve, and movable therefrom to open the valve to permit fuel to pass therethrough toward the internal combination engine. The generally elongated valve needle is comprised of a generally elongated generally central shaft section having a first diameter, and a free end section having a second diameter greater than the first diameter, the
Cohen James H.
Ording Richard B.
Kashnikow Andres
Nguyen Dinh Q.
Siemens Automotive Corporation
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