Internal-combustion engines – Charge forming device – Auxiliary air or gas used to inject fuel
Patent
1992-03-23
1993-12-14
Dolinar, Andrew M.
Internal-combustion engines
Charge forming device
Auxiliary air or gas used to inject fuel
F02M 6700, F02M 6908, F02M 6950
Patent
active
052692817
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The invention is based on an apparatus for injecting a fuel-air mixture for multi-cylinder internal combustion engines.
In injection apparatuses of this kind, in contrast to previously conventional fuel injection devices, it is not pure fuel but rather a mixture of fuel and a supporting air flow diverted from the intake line of the engine that is brought to the injection points of the engine. The fuel-air mixture is carried to the injection points of the various cylinders of the engine via the injection lines connected to the various distributor bores. The injection point may be the intake tube, leading to each engine cylinder, of the intake line or the inlet valve of the cylinder. Mixing the fuel prior to the actual injection into the cylinder results first in better preparation of the fuel and hence more favorable combustion in the engine; second, it offers the opportunity to supply a plurality of engine cylinders while having exact metering, using only a single fuel injection valve.
In a known apparatus of the type referred to at the outset above (German Patent Disclosure Document 37 10 127 A1), the valve member is embodied on a sheath that is axially displaceably guided on a shaft and is connected to the electromagnet. The shaft has a flange on one end that rests on the distributor and has fuel metering bores that ar coaxial to the distributor bores; on the top of the flange, remote from the distributor, these bores are closed by the valve member, which is pressed onto the flange by a valve closing spring. Upstream of the flange as viewed in the fuel flow direction, there is a valve chamber receiving the valve closing spring; this chamber communicates on the one hand with the fuel inflow, via the hollow-cylindrical annular conduit, which is coaxial with the shaft, between the sheath and the electromagnet and on the other with the fuel return, via a pressure regulating valve.
Advantages of the Invention
The apparatus according to the invention has an advantage, while having a very simple structure, of meeting the requirement for an only extremely slight variation in quantity of the fuel metered to the various distributor bores. Because of the position of the fuel inlet into the valve chamber between the valve seat and the valve needle guide, a uniform oncoming flow to the various fuel metering bores, unimpeded by the valve needle motion, is attained, and as a result in turn the fuel streams flowing out of the various distributor bores differ from one another in quantity only very slightly.
The apparatus according to the invention also has the advantage that a side-feed valve known per se, as used in in-line injection pumps for each engine cylinder, can be used as the fuel injection valve with only slight structural changes. This kind of side-feed valve is described in German Patent Disclosure Document DE 37 05 848 A1, for instance. The structural changes comprise shifting the at least one connecting bore leading to the valve chamber, and embodying the distributor chamber so that the fuel metering bores are on the side of the valve seat remote from the valve chamber.
With the provisions recited herein, advantageous further features of and improvements to the apparatus disclosed are possible.
In a preferred embodiment of the invention, the valve needle, with a guide section, and the valve chamber are dimensioned such that the inside annular cross section of the valve chamber remaining between the valve needle and the inner wall of the valve chamber is 40 to 80 times greater than the annular seat cross section. Moreover, the at least one connecting bore is dimensioned such that the inside annular cross section between the valve needle and the inner wall of the valve chamber is 10 to 20 times greater than the cross section of the connecting bore. This structural dimensioning creates a compensation volume in the valve chamber between the valve needle guide segment and the valve seat, and this volume assures adequate smoothing of fuel fluctuations upstream of the valve seat. In
REFERENCES:
patent: 4708117 (1987-11-01), Mesenich et al.
patent: 4709681 (1987-12-01), Rozsas
patent: 4754740 (1988-07-01), Emmenthal et al.
patent: 4794901 (1989-01-01), Hong et al.
Dolinar Andrew M.
Greigg Edwin E.
Greigg Ronald E.
Robert & Bosch GmbH
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