Internal-combustion engines – Charge forming device – Auxiliary air or gas used to inject fuel
Patent
1991-11-20
1993-04-20
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
052033082
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The invention is based on a device for injecting a fuel-gas mixture as defined hereinafter. German Patent Application P 39 31 490.1 has already proposed a device for injecting a fuel-gas mixture having a distributor housing that has a gas delivery opening extending concentrically with a longitudinal valve axis, as well as distributor openings aimed at injection ports of a fuel injection valve; the gas delivery opening communicates with the distributor openings. However, the fuel stream is injected from the injection ports into the distributor openings not directly but rather in the form of a free stream, so that peripheral mists of fuel and portions of the core stream strike the inner walls of the distributor housing. Since moreover the fuel stream is not enveloped by the gas stream and the gas speed is low, the gas in this distributor chamber formed by the distributor housing and the fuel injection valve does not exert any substantial aiming effect on the fuel. Especially if the fuel injection valve is in an inclined position, the danger exists that the film of fuel on the wall in the peripheral region of the gas flow will flow back upstream to the gas delivery opening or will reach some other distributor opening. Fuel can become deposited in the corners or edges of the distributor chamber and can cause disruptive dribbling, for instance after the fuel injection valve has been switched off.
In the device proposed in German Patent Application P 39 31 490.1, reliable, exact fuel metering to the various distributor openings is therefore not always assured.
ADVANTAGES OF THE INVENTION
The device according to the invention for injecting a fuel-gas mixture has an advantage over the prior art of particularly accurate allocation of fuel to the various distributor openings or to the various cylinders of an engine, and of maximally homogeneous mixture formation. The aimed fuel stream is injected through the injection ports of the injection end into the distributor openings of the distributor housing via the fuel transport conduits and is transported onward all the way downstream by the gas delivered via the gas gap, thereby preventing the formation of a fuel film on the inner walls of the distributor housing.
In the mixture formation zone, virtually no corners, edges or gaps in which fuel can become deposited are formed; after the shutoff of the fuel injection valve, for instance, such deposits cause disruptive dribbling and nonhomogeneous formation of the fuel-gas mixture.
Advantageous further developments of and improvements to the device disclosed are possible with the provisions recited herein.
It is advantageous if the gas gap, at its narrowest point, has a smaller cross-sectional area than the gas delivery opening. Because of the throttling of the gas flow, making the gas gap narrow not only permits metering of the gas to the various distributor openings but also accelerates the gas to a high speed in the direction of the distributor openings, which improves mixture formation and prevents the fuel from flowing back upstream.
For a particularly simple embodiment of the fuel transport conduits and gas gaps, it is advantageous if the valve cap is provided with a number of frustoconical projections, corresponding to the number of distributor openings and each aimed at a respective distributor opening; the fuel transport conduits extend through these projections, which protrude into frustoconical indentations of the distributor housing with a spacing such that the at least partially encompassing gas gaps are formed between the circumference of the projections and the surface of the indentations.
It is advantageous if the gas delivery opening communicates with the gas gap through a gas distributor chamber embodied concentrically with the longitudinal valve axis between the valve cap and the distributor housing, so that a particularly uniform delivery of the gas to the gas gaps takes place.
It is especially advantageous if the smallest diameter of the projection is smaller than the di
REFERENCES:
patent: 4708117 (1987-11-01), Mesenich et al.
patent: 4709681 (1987-12-01), Rozsas
Dolinar Andrew M.
Greigg Edwin E.
Greigg Ronald E.
Robert & Bosch GmbH
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