Fluid sprinkling – spraying – and diffusing – Including valve means in flow line – Reciprocating
Reexamination Certificate
2000-12-01
2002-08-13
Morris, Lesley D. (Department: 3752)
Fluid sprinkling, spraying, and diffusing
Including valve means in flow line
Reciprocating
Reexamination Certificate
active
06431471
ABSTRACT:
BACKGROUND INFORMATION
1. Field of the Invention
The present invention relates to a bi-fuel injector, in particular for combustion engines, as well as to a method of injection.
2. Background of the Invention
In general, bi-fuel injectors are used for injecting or for supplying various liquids in devices such as, e.g., internal combustion engines, air conditioning units, a moistening apparatus or reformers in fuel cells.
In internal combustion engines or combustion engines, fuel and a liquid additive are injected into the combustion chamber of an internal combustion engine so as to reduce pollutant emission of the internal combustion engine, and if applicable, to increase its efficiency. Such a bi-fuel injector is for example disclosed in German Patent Application No. 197 46 489 A1 which describes a bi-fuel nozzle for injection of diesel fuel as well as a liquid additive, such as e.g. water, into a combustion chamber of an internal combustion engine. Several 2/2-way valves arranged outside the actual nozzle body regulate the conveyance of fuel into, and out of, a pressure chamber. When the fuel is conveyed out of the pressure chamber, liquid additive can flow into the pressure chamber via a check valve and is thus made available for injection.
For example, in order to further reduce pollutant emission of combustion engines and to comply with increasingly stringent limiting values and statutory standards, it is necessary to take into account the cold start emission of motor vehicles, including passenger motor vehicles. Furthermore, an improvement in cold-start behavior and in operation during the warm-up period is desirable.
One approach to achieving this is to divide the fuel into a component which is injected during cold starting resulting in optimal results during the warm-up period, and a fraction which is supplied when the engine is warm.
Approaches followed up to now have provided two separate injection valves in order to supply the various liquids or fuel fractions or fuels to the respective devices, for example to the combustion chamber of the engine. This is however associated with the disadvantage in that it requires considerable space and that there is insufficient space, e.g. in the intake manifold, to direct both injection valves directly to the inlet valves of the engine. In other words, the position achieved is not optimal, which in turn leads to impaired efficiency. Furthermore, this approach is very costly.
Attempts have thus been made to supply both liquids, in particular both fuels or types of fuel, via one injection valve. This is however associated with the problem that there is insufficient space in the valve itself for active switchover.
By contrast, if separation into shutoff valves is effected outside the injection valves, then large residual volumes of the liquid to be shut off prevent quick switchover, or in the case of combustion engines, prevent effective pollutant reduction in the cold-start phase. In other words, the volumes of the pipes and the injection valves up to their exit apertures may for example still contain fuel unsuitable as a starting fuel. But in the case of combustion engines, pure starting fuel should be available right from the first injection stroke, so as to achieve effective pollutant reduction in the cold-start phase.
SUMMARY OF THE INVENTION
It is an object of the present invention to create a bi-fuel injector which is particularly suitable for combustion engines and which allows quick switchover when different liquids and/or fuels are supplied. For example when applied in combustion engines or internal combustion engines, a more effective pollutant reduction particularly in the cold-start phase is to be achieved by the invention. Furthermore, a method of injection is to be disclosed which allows a quick changeover of liquid so that e.g. pollutant reduction in particular during cold start of a combustion engine can be effectively reduced. According to a further aspect, high reliability is to be ensured.
Characteristics and advantages of the present invention which have been provided in the following description of the bi-fuel injector, also may apply to the method of injection according to the present invention. Furthermore, characteristics and advantages provided in the description of the method of injection, also may apply to the bi-fuel injector according to the present invention.
The bi-fuel injector according to the present invention, which e.g. is suitable for combustion engines, comprises a nozzle body with a nozzle exit, a moveably held valve needle for opening and closing the nozzle exit, a first supply channel for supplying a first liquid to the nozzle exit, a second supply channel for supplying a second liquid or a liquid additive to the nozzle exit, as well as a slide gate which is arranged in a chamber of the nozzle body and which is hydraulically operable, and which depending on its position, either connects the first supply channel or the second supply channel to the nozzle exit.
The bi-fuel injector according to the present invention makes it possible to supply two different liquids and/or different types of fuel via a single injection valve. This results in particular in an effective reduction of pollutants, especially in the cold-start phase of a combustion engine. A quick change between liquids is possible with high reliability. During cold starting for example, pure starting fuel is available from the very first injection stroke. The volumes in the injection valve up to the exit apertures are very small. Furthermore, injection can take place in an optimal position, resulting e.g. in more effective combustion and more effective pollutant reduction. Costs are significantly reduced not only because there is no need for a second injection valve for the second liquid or for the second fuel, but also because there is no need for an expensive control system for example via additional valves. The bi-fuel injector is particularly reliable because there are no control systems or complex components susceptible to failure, or alternatively such control systems are reduced to a minimum.
Preferably, the slide gate is designed as a ring-shaped piston and the chamber in which the slide gate is located is e.g. a toroidal chamber. This saves additional space and allows economical design which is advantageous especially for series production.
Preferably the slide gate separates the first liquid from the second liquid or the first fuel from the second fuel or from the liquid additive. Mixing of the various liquids or fuels is avoided in this way, and the slide gate can e.g. be designed so as to be effective as a result of the pressure differential between the two liquids or fuels, which for example are located on opposite sides of the slide gate.
Preferably, targeted leakage or a leakage gap for the return flow of the first liquid is provided, so as to flush the bi-fuel injector during activation of the slide gate. This also results in the selected liquid being available immediately, so that for example during cold starting of an engine, a cold-start fuel is injected from the very beginning. Preferably there is an aperture or a gap to this effect between the valve needle or the valve needle head and the respective guide, with liquid or fuel, located between the slide gate and the nozzle exit, being able to flow back into the first supply channel if the second supply channel is connected.
Preferably, the slide gate can be moved between a first position and a second position, whereby in the first position the second supply channel is closed by the slide gate while the first supply channel is open; and in the second position the first supply channel is closed by the slide gate while the second supply channel is open.
For example, the chamber in which the slide gate is located is connected to the first supply channel by a first aperture, and to the second supply channel by a second aperture, with in particular, a further aperture being provided to the nozzle exit, and with the slide gate, depending on its position, closing off ei
Anzinger Claus
Bokodi Attila
Holder Eberhard
Kroetz Gerhard
Legner Wolfgang
Daimler-Chrysler AG
Davidson Davidson & Kappel LLC
Morris Lesley D.
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