Injection valves for liquid-fuel mixtures and associated process

Details Injection valves for liquid-fuel mixtures and associated process Injection valves for liquid-fuel mixtures and associated process

1995-12-27

1997-09-23

Moulis, Thomas N.

Internal-combustion engines

Water and hydrocarbon

123256, F02M 4304, F02M 4702

Patent

active

056693346

DESCRIPTION:

BRIEF SUMMARY
FIELD OF THE INVENTION

The invention concerns injection systems for intermittent introduction of fuel-liquid mixtures into combustion spaces of an internal-combustion engine and a process for the operation of injection systems of the invention,


BACKGROUND AND PRIOR ART

In order to reduce pollutant emissions in the exhaust and to reduce the fuel consumption of diesel engines, liquid can be injected with the fuel into the combustion spaces of the diesel engine. However, the service life of the injection pump is greatly reduced due to corrosion and cavitation, if liquid and fuel are mixed prior to the injection pump.
It is known from U.S. Pat. No. 5,174,247 how to inject fuel and water together by means of an injection valve into a cylinder of a diesel engine. Fuel and liquid inlet lines to an injection valve are alternately opened and closed, so that a layered fuel-water mixture is formed in the injection valve.
It is known from EP-C 0 064,146 how to inject two fuels through one injection valve into a cylinder of an internal-combustion engine. Both fuels are introduced into the injection valve separately and meet each other first in the region of a tip of a valve member. A piston is provided inside the injection valve, and this piston is connected with the tip of the valve member, and a pressure reduction is effected between injections, by creating additional volume in front of the injection opening.
Conventional fuel injection systems, as they are disclosed in the two above-noted documents, produce the necessary high pressure for introducing the fuel into the combustion spaces of internal combustion engines, such as, e.g., diesel engines, with pumps that are directly driven by the internal combustion engine. At low engine speed, the pump capacity may be insufficient, and the fuel injection may be imprecise, which leads to losses in performance and elevated pollutant emissions from the internal-combustion engine.
So-called common-rail systems are known in which a central pump supplies the fuel into a high-pressure reservoir, so-called common-rail pressure reservoir, and from there continuously, and free of pulsations via lines to the injection valve. These systems isolate the injection from the pressure fluctuations that occur in conventional pumps driven directly by the engine when there are large differences in engine speed.
A common-rail injection system is known (see The electronically controlled dynamic rail injection system (DIS), Ganser-Hydromag), in which fuel coming from a fuel tank is supplied by means of a high-pressure pump into a large-volume pipe system, which is joined with the injection valve. The injection valves are actuated by hydraulic pressure, and electromagnetic valves control the opening and closing of the injection valves as a function of the operating parameters of the internal-combustion engine. A disadvantage of this injection system is that the high pressure produced by the pump is applied over long lengths of lines up to the injection openings of the injection valves, even though no injection is produced, and thus leaking of the fuel, for example, may occur both at the connection joints of the lines as well as at the closed injection openings in front in the combustion spaces. Further, this state of the art gives no indication of how a liquid, such as, e.g., water or methanol, can be introduced additionally into the fuel in front of the injection openings. Lubrication is problematical, as is also the selection of materials, and the corrosion and cavitation of pumps that are suitable for producing a constant fluid pressure at or above the fuel pressure.


SUMMARY OF THE INVENTION

An object of the invention is to create an injection system for the intermittent introduction of fuel-liquid mixtures into the combustion spaces of an internal-combustion engine and a process for operation of this injection system for intermittent introduction of fuel-liquid mixtures, which reduces wear of the pumps, keeps pressure fluctuations of the pumps away from the injection valves, and avoids

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Ganser, M. Ing "The Electronically Controlled . . . " Ganser-Hydromag pp. 1-24. No Date.

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