Fluid sprinkling – spraying – and diffusing – Fluid pressure responsive discharge modifier* or flow... – Fuel injector or burner
Patent
1990-11-07
1992-06-30
Kashnikow, Andres
Fluid sprinkling, spraying, and diffusing
Fluid pressure responsive discharge modifier* or flow...
Fuel injector or burner
2395338, F02M 4700
Patent
active
051255804
DESCRIPTION:
BRIEF SUMMARY
The invention relates to a fuel injection nozzle, particularly a pump jet with a nozzle plunger that is spring-loaded in the closing direction, whereby the nozzle plunger extends, with its end turned away from the spray openings, into a damping chamber that can be filled with fuel and has a pressure pin that is surrounded with a stabilized projection that forms a stop for one shoulder of the nozzle plunger and whereby the stabilized wall of the damping chamber, during the stroke movement of the nozzle plunger, defines a throttle opening, which opens into a drain and/or another chamber.
In EP-A 267 177 and EP-A 277 939, fuel injection nozzles are described which make possible the division of the injection process into a pilot injection and a main injection by the use of a shunting piston. The very difficult problem of insuring a practical injection process under different operating conditions is solved in principle there by the damping of the shunting piston motion, but a few inconveniences still exist.
In a pump jet according to the state of the art, malfunctions in the injection process are observed relatively frequently. Sometimes the shunting piston opens too late, sometimes the pilot injection starts too late and supplies a quantity that is too low, sometimes it is omitted entirely. It is assumed that these malfunctions develop because of statistical variation in the pump supply pressure curve and in the dynamic opening pressure of the valve needle, e.g. if the valve needle has not opened yet when the dynamic opening pressure of the shunting piston is attained. An increase in this opening pressure would help, but is not possible, because the pilot injection would then last too long. This could only be achieved by a weaker damping of the shunting piston; however, because of that, the pilot injection quantity at low rpm would again be too low or at high rpm too high. The latter is undesirable for reasons of combustion dynamics and it also occurs already without increasing the dynamic opening pressure of the shunting piston. At high speed and full throttle, the pilot injection continues on into the main injection without an injection pause.
Since when the nozzle plunger is raised, the volume in the pressure chamber increases suddenly, at low speed, the injection pressure first decreases so that with a low dynamic opening pressure of the shunting piston for the reasons named above, the pilot injection quantity is too low.
To optimize the combustion curve, however, it is desirable that the pilot injection quantities are as close as possible to equal at all engine speeds and load conditions and the duration of the pilot injection and the injection pause in degrees crankshaft is as close as possible to equal at all engine speeds.
These ideal conditions are described as the combustion process in DE-OS 37 35169, but without any information on realizing them.
In principle, a subdivision of the injection process into a pilot injection and main injection has been already implemented with nozzles having nozzle plungers that work together across their stroke with two different springs. The disadvantages, of such so-called two-spring nozzle plunger brackets is the situation where the moved weights become greater and two springs with different spring characteristics result in a system that can vibrate. The effort for adjusting this type of equipment is thus relatively high and the separation into pilot injection and main injection can not always be reproduced over the engine speed curve.
The goal of the invention is to permit an exact separation into pilot injection and main injection with a simple design of the injection nozzle and particularly to maintain a high measure of precision and reproducibility over the entire engine speed range with small stroke and low moved weights. All in all, the goal of the invention is to create a simple injector nozzle which permits achievement of an optimum course of injection over time. To solve this task, the fuel injector nozzle of the type mentioned above according to the invent
REFERENCES:
patent: 4576338 (1986-03-01), Klomp
patent: 4624135 (1986-11-01), Bungay et al.
patent: 4840310 (1989-06-01), Haider
Kashnikow Andres
Morris Lesley
Voest-Alpine Automotive Gesellschaft m.b.H.
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