Fluid sprinkling – spraying – and diffusing – Fluid pressure responsive discharge modifier* or flow... – Fuel injector or burner
Reexamination Certificate
2000-05-03
2001-11-06
Scherbel, David A. (Department: 3752)
Fluid sprinkling, spraying, and diffusing
Fluid pressure responsive discharge modifier* or flow...
Fuel injector or burner
C239S491000, C239S585100
Reexamination Certificate
active
06311900
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to a procedure for injecting fuel in particular into the combustion chamber of internal combustion engines via a swirl injection nozzle with axially movable valve needle, wherein the pressurized supplied fuel is made to rotate around the valve needle in an annular swirl chamber arranged in front of the outlet nozzle. The invention also relates to an injection nozzle suitable for executing the procedure.
2. The Prior Art
Numerous procedures and devices are already known for injecting fuel directly into the combustion chamber of both diesel and Otto engines. The fuel is injected into the combustion chamber of the engine and atomized via a pump-nozzle system or a pump-line-nozzle system (common-rail system) during compression. The injection process can also take place in several phases, so-called, pre- and main injection. One significant feature shared by these injection systems is that atomization takes place from the rest phase of the liquid. In a period measuring in the milliseconds, the potential energy is used for conversion into kinetic energy (fuel velocity), and the low quantity of fuel is atomized to the nozzle outlet opening.
DE-OS 24 60 111 already discloses a generic injection nozzle for injecting a liquid in a chamber subjected to pressure fluctuations during a low-pressure phase.
The supplied fuel enters an annular chamber arranged around the nozzle needle guide, and from the latter via tangential inflow openings at the end of the nozzle needle guide into an annular swirl chamber, which is arranged around the nozzle needle. An annular flow is built up inside the swirl chamber, and stored therein. Given a higher volume of the swirl chamber, the rotational effect can be amplified even further by arranging at least one reflux opening in the swirl chamber, which preferably connects to the swirl chamber in a roughly tangential manner, and is located at the top end of the annular chamber in the nozzle needle guide. The tangential inflow opening and tangential reflux opening are arranged opposite relative to the direction of flow. As indicated in this publication, the fuel is to be intermediately stored rotating in the swirl chamber. Intermediate storage is only on hand if the reflux opening is also closed at least with the nozzle outlet opening closed. As a consequence, the rotational velocity decreases during intermediate storage. During the ejection process, the flow of fuel divides into two partial streams with the reflux opening open, wherein the upwardly directed partial current generates swirls in the direction of the reflux opening that have a negative effect on the atomization quality.
Also known is an electromagnetic fuel injection valve for internal combustion engines (U.S. Pat. No. 4,179,069), which is intended in particular for the injection of fuel into the suction pipe of a vehicle motor. The fuel is injected via a swirl injection nozzle with axially moveable valve needle, wherein the pressurized fuel is made to rotate around the valve needle in an annular swirl chamber arranged directly in front of the outlet nozzle, and the fuel is introduced into the swirl chamber at its largest radius through a fuel inlet line that generates the peripheral velocity component. The fuel flow is removed where the radius of the swirl chamber is narrowest, concentrically to the valve needle. During the injection phase, removal of the fuel from the swirl chamber is interrupted.
A procedure for injecting fuel via a swirl injection nozzle with axially moveable valve needle is also known from U.S. Pat. No. 4,805,837. An annular swirl chamber is arranged directly in front of the outlet opening of the nozzle. The fuel is introduced into the swirl chamber at its largest radius, and removed concentrically to the valve needle where the radius of the swirl chamber is narrowest with the outlet opening closed. During the injection phase, removal of the fuel is interrupted.
The disadvantage to the known injection procedures mentioned above is generally that the injection quantity for achieving an optimal injection progression cannot be varied sufficiently, and the achievable atomization quality does not reflect the set high requirements.
SUMMARY OF THE INVENTION
The object of the invention was to develop a procedure for injecting fuel, in particular into the combustion chamber, of internal combustion engines, which makes it possible to achieve a rotationally symmetric distribution of fuel during entry into the combustion chamber, which ensures a high atomization quality, in particular as the injection process starts out already, along with an optimal injection progression while the nozzle outlet opening is open, and which makes it possible to vary the injection quantity at the same preliminary pressure and constant opening time for the valve needle.
In addition, the object is to provide an injection nozzle that is inexpensive to manufacture and suitable for executing the procedure.
The fuel is introduced into the swirl chamber where its radius is largest, preferably through channels running tangentially or inclined from top to bottom, and removed form the swirl chamber where its radius is smallest concentrically to the valve needle with the nozzle outlet opening closed. The fuel introduced into the swirl chamber is therein subjected to a nearly level, rotationally symmetric flow progression. In addition to the peripheral velocity component, this flow also exhibits a radial component directed toward the vertical axis of the swirl chamber, and hence toward the valve needle, wherein the axial velocity component is negligible.
To inject the fuel into the combustion chamber, the valve needle is opened, and the reflux quantity of the fuel is partially or completely throttled out of the swirl chamber at the same time. The fuel is not injected into the combustion chamber at rest, but under conditions of an already existing kinetic energy owing to the applied rotational velocity via the delivery pressure of the pump formed at the time of injection. Since the flow progression of the rotating fuel is already directed toward the nozzle needle right at the time of injection into the combustion chamber, is not subject to any additional change in direction in the swirl chamber by the opening of the nozzle needle, an improved atomization quality is achieved. In addition, the fuel flow already possesses a high kinetic energy at this time. The proposed procedure is suitable for injection systems with continuously or discontinuously operating injection pumps, and for so-called common-rail systems. The fuel rotating in the swirl chamber should preferably execute at least one complete rotational motion around the valve needle before the injection process is initiated. This ensures a particularly high atomization quality.
According to the procedure, the injection process can be controlled by varying both the fuel fed into the swirl chamber, and the fuel removed form the swirl chamber.
The fuel can be introduced into the swirl chamber through several entry opening s or channels with identical or varying cross-sectional surfaces, wherein the respective partial fuel quantities can also vary. An additional varying time controller can be used for a so-called pre and main injection. To achieve the desired rotation of the fuel inside the swirl chamber, the fuel must be introduced into the swirl chamber via an inlet line running tangentially or inclined from top to bottom.
The reflux or removal of the fuel from the swirl chamber can take place in several phases, whose chronological sequence can be varyingly controlled, so that different partial quantities flow out at defined points in time. In the pump-nozzle system, it makes sense to control the change in cross section of the outlet opening inside the injection nozzle via the movement progression of the valve needle. Various injection quantities can be realized according to the procedure as follows, with the preliminary pressure remaining constant and the valve needle releasing the nozzle ou
Kohlmann Jürgen
Slowik Günter
Hwu Davis
Scherbel David A.
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