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
F02M 6116
Patent
active
051255812
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, in which the pressure chamber in front of the nozzle plunger seat is connected to an accumulator chamber limited by a spring-loaded shunting piston, whereby the shunting piston is stressed, on its end turned toward the accumulator chamber, by the pressure in a damping chamber that can be filled with fuel and has a pin that extends into a plate that limits that damping chamber and has an opening.
A fuel injection nozzle of this type, described in EP-A 277 939, makes possible the separation of the injection process into a pilot injection and a main injection. 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 desireable 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 35 169, but without any information on realizing them.
The goal of the invention is now to further develop an injection nozzle of the type mentioned at the beginning that improves response speed and dynamic behavior. In particular, the version according to the invention should assure that a secure function is maintained by moving the lowest possible weight of shunting piston and by rapid motions. To solve this task, the embodiment according to the invention basically consists of the fact that the cylindrical driving part of the shunting piston has a diameter to height ratio of 1:0.1 to 1:0.4, that the shunting piston has, on the side turned toward the accumulator chamber, a pin with variable cross section that extends into the limiting plate and that the shunting piston has a guiding extension with grooves, on its side turned towards the accumulator chamber.
Because of the fact that the dimensions of the shunting piston have been chosen to deviate from the known embodiments in such a way that only a relatively small height is provided in the stroke direction, the moved mass is significantly decreased. However, a shunting piston with this type of structure, almost disc shaped, would also have an increased tendency to slanted positions in the shunting piston guide path in the inside of the respective
REFERENCES:
patent: 2279010 (1942-04-01), Nichols
patent: 4928886 (1990-05-01), Kronberger
Patent Abstracts of Japan--vol. 10, No. 218 (M-503) (2274), Jul. 30, 1986 and JP-A-61 (Isuzu Motors Ltd.), Mar. 19, 1986.
Kashnikow Andres
Morris Lesley D.
Voest-Alpine Automotive Gesellschaft m.b.H.
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