Internal-combustion engines – Water and hydrocarbon
Reexamination Certificate
1999-07-28
2001-08-14
Wolfe, Willis R. (Department: 3747)
Internal-combustion engines
Water and hydrocarbon
Reexamination Certificate
active
06273032
ABSTRACT:
SPECIFICATION
PRIOR ART
The invention is based on a dual-substance nozzle for an internal combustion engine.
One such dual-substance nozzle is known for instance from German patent disclosure DE 39 28 611 A1.
Dual-substance nozzles serve to provide laminated injection of fuel and a supplementary fluid, such as Diesel fuel and water, into the combustion chamber of an internal combustion engine so as to reduce pollutant emissions from the engine and optionally to increase its efficiency.
A disadvantage of such known dual-substance nozzles is the possible mixing of fuelless supplementary fluid, or as a rule of Diesel with water, which is possible in the structural tracts upstream and downstream of the injection nozzles. For instance, the two components can mix together as a result of reflux of the supplementary fluid into the tank by way of leaks, and so forth.
Another disadvantage of the known dual-substance nozzles is that the injection can in principal occur only in laminar fashion; that is, fuel and supplementary fluid cannot be injected parallel, for instance.
From German patent DE 43 37 048 C2, an injection system with a dual-substance nozzle is also known that realizes what is known as the common rail technique, in which all the injection nozzles serving the engine are charged with fuel at high pressure from a common rail pressure reservoir.
Since for the injection event for the known dual-substance nozzle the entire injection volume, that is, fundamentally the fuel quantity and the supplementary fluid quantity (which for instance is one-third the fuel quantity), must be injected by means of the common rail pressure, and of that again approximately one-third is replaced by supplementary fluid by means of low pressure; that is, the high pressure attained for this one-third is nullified; the disadvantageous result is a fuel pumping output that is at least one-third higher than in normal fuel injection.
It is also disadvantageous in the known fuel injection system that one complicated and relatively expensive 3/2-way valve is needed for each individual injector for metering the quantity of supplementary fluid, as well as one further 3/2-way valve for controlling the Diesel injection quantity. For prestorage of the supplementary fluid, the fuel delivery from the common rail pressure reservoir to the injection nozzle is disrupted using the first 3/2-way valve and at the same time a pressure chamber surrounding the injection nozzle and in which fuel at high pressure is stored is drained off to the low-pressure fuel side by means of a suitable position of the first 3/2-way valve. By means of the resultant pressure drop in the pressure chamber, supplementary fluid is fed via a suitable line into the pressure chamber and positively displaces the equivalent volume of fuel. Next, the first 3/2-way valve is returned to a position that establishes a communication between the common rail pressure reservoir and the pressure chamber in the injection valve. For quantitatively precise metering of the fuel quantity to be injected and that is intended to follow the prestored supplementary fluid in the injection surge caused by the next valve opening, the further 3/2-way magnet valve is provided, which selectively connects the back end of the nozzle needle, which is held in the closing position by a spring, selectively with either the common rail pressure reservoir or the low-pressure fuel side and as a result chronologically controls the valve needle stroke, the opening and closing of the valve, and thus the desired injection quantity.
In principle, the known fuel injection system for each individual injector requires the two precise and thus complicated 3/2-way control magnet valves, so that both the desired fuel quantity and the required quantity of supplementary fluid can be metered exactly.
ADVANTAGES OF THE INVENTION
The dual-substance nozzle, for the sake of strict separation of fuel injection from supplementary fluid injection will be set fourth hereinafter. Any mixing of fuel with supplementary fluid before the actual injection is thus precluded. The two fluids can at most meet one another in the combustion chamber of the internal combustion engine equipped with the dual-substance nozzle of the invention.
An advantage of using the dual-substance nozzle of the invention is also that at arbitrary times, supplementary fluid can be added to the fuel injection stream or injected for other cooling purposes. For instance if water and Diesel are injected at parallel times in Diesel engines, then the total injection time is shortened, which in terms of NO
x
production leads to considerably more favorable results during combustion.
The actual Diesel injection nozzle ports can be kept smaller, which is advantageous for the combustion behavior at low load.
Another considerable advantage of the dual-substance nozzle of the invention is that because the supplementary fluid is carried on the outside, cooling annularly around the injector takes place, which precisely in the full-load phase, in which large quantities of high-pressure fuel must be injected, causing heating of the injector, represents a substantial improvement.
A fuel injection system for an internal combustion engine which is equipped with a dual-substance nozzle of the invention is also within the scope of the invention. Especially if the fuel injection system makes use of the above-described, known common rail technique for fuel injection, the two complicated and expensive 3/2-way magnet control valves can be replaced by a single, simpler and less expensive 2/2-way valve in the fuel injection line between the common rail pressure reservoir and the fuel inlet bore in the nozzle body; by suitable timing control, this valve performs the quantity metering for the fuel quantity to be injected.
The lost one-third of power mentioned above in the injection event with internal storage of the supplementary fluid can be reduced to only a few percent if the dual-substance nozzle of the invention is used, because of the deposit of the supplementary fluid on the outside; this is true even if a pressure of 100 bar or more must be brought to bear by the supplementary fluid supply.
An embodiment of the dual-substance nozzle invention that is especially preferred is one in which the jacket, which closes off the hollow chamber, intended for receiving supplementary fluid, on the outside is welded in an annularly sealing fashion on its upper end to the nozzle body and on its lower end rests raisably on the nozzle body with a defined pressure and thus forms a sealing joint which presses against a lip-like sealing seat on the nozzle body and is capable of opening in order to inject supplementary fluid into the combustion chamber as soon as the supplementary fluid in the interior of the hollow chamber exceeds a certain differential pressure from the ambient pressure. The injection nozzles for the supplementary fluid can in particular be embodied by bores in the sealing joint downstream of the contact region with the sealing seat.
Another particular advantage of the dual-substance nozzle of the invention is the possibility of structural variation of the injection angle &bgr; of the supplementary fluid relative to the longitudinal axis of the nozzle body and thus also relative to the injection direction of the fuel into the combustion chamber. According to the invention, by a correct setting of the angle &bgr;, the dual-substance nozzle can be operated in such a way that the injected supplementary fluid in the combustion chamber strikes simultaneously injected fuel and by its impetus brings about a deflection of the fuel particles away from the wall of the combustion chamber, so that cooling down of the combustion chamber wall by as yet unignited fuel striking it is prevented.
The sealing joint in the above-described embodiment of the dual-substance nozzle of the invention is also intended to seal off the hollow chamber with the supplementary fluid in fluid-tight fashion even after a very high number of injection events, by resilient contact with and suppor
Harndorf Horst
Ruoff Manfred
Ali Hyder
Greigg Edwin E.
Greigg Ronald E.
Robert & Bosch GmbH
Wolfe Willis R.
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