Fuel injection device for internal combustion engines

Details Fuel injection device for internal combustion engines Fuel injection device for internal combustion engines

1997-02-25

1998-10-20

Moulis, Thomas N.

Internal-combustion engines

Combustion chamber means having fuel injection only

Having a particular relationship between injection and...

239456, F02B 500, F02M 6118

Patent

active

058231617

DESCRIPTION:

BRIEF SUMMARY
PRIOR ART

The invention is based on a fuel injection device for internal combustion engines. In one such fuel injection device, known from the professional 1992, pp. 28-30, a high-pressure pump feeds fuel out of a low-pressure chamber into a high-pressure collection chamber (common rail) and there builds up a high-pressure fuel level that is available for the injection, regardless of the engine rpm. From the common rail, high-pressure lines corresponding to the number of injection locations lead away to the individual injection valves that protrude into the combustion chamber of the engine to be supplied; the high-pressure lines discharge there into a pressure chamber that urges the valve member in the opening direction. The control of the opening stroke motion of the valve members of the injection valves, embodied as "inward-opening injection nozzles", is effected by means of a 3/2-way valve, which is inserted into a partial line branching off from the high-pressure line and discharging into a control chamber that urges the valve member in the closing direction. The pressure engagement face, acting in the closing direction, on the valve member of the injection valve is larger than the pressure face acting in the opening direction, so that the valve member, when the control chamber is acted upon by high pressure, is kept pressed against its valve seat. If injection is to occur, the 3/2-way valve connects the control chamber with a fuel tank, so that the pressure in the control chamber is relieved into the tank, and the opening force engaging the valve member is now sufficient to lift the valve member from its seat, so that fuel can be injected via the injection openings. For closing the injection valve, the control chamber is reconnected to the high-pressure line. For shaping the course of injection, a throttle is inserted into the connecting line between the tank and the control chamber, and for rapid closure of the valve member at the end of injection, a check valve that opens in the direction of the control chamber is used.
The known fuel injection device has the disadvantage, however, that with the injection valves used variable injection cross sections are not possible. Especially at low rpm and low load, because of the very high injection pressure in the common rail, this leads to very brief injection durations, which have a disadvantageous effect on fuel preparation in the combustion chamber and consequently on the quality of combustion.
Moreover, the use of a complicated 3/2-way valve to control the injection event is very complicated, making it complicated and expensive to produce the known fuel injection device.


ADVANTAGES OF THE INVENTION

The fuel injection device according to the invention for internal combustion engines, has the advantage over the prior art that the known common rail injection system can be improved such that the advantages of the constantly available high injection pressure can be utilized consistently by means of a variable injection cross section at the injection valve. This is advantageously made possible by the use of an injection valve with an outward-opening valve member, by way of whose adjustable opening stroke a variable injection cross section can be controlled.
The injection valve of the outward-opening type can be controllable in infinitely graduated fashion, to which end an annular gap that can be opened as a function of the valve member stroke and is located between the closing head and the valve seat forms the injection cross section. Advantageously, the injection cross section is meant to be controlled by means of a slide valve preceding the sealing cross section; in its valve member, this slide valve has a plurality, for example, of geometrically accurately determined injection openings, by way of whose arrangement, as a function of the opening stroke, precise injection cross sections can be adjusted when these injection openings emerge from coincidence with the housing. These injection openings are advantageously formed by two rows of injection ports loc

REFERENCES:
patent: 4905908 (1990-03-01), Sczomak
patent: 5020728 (1991-06-01), Linder et al.
patent: 5048489 (1991-09-01), Fischer
patent: 5551634 (1996-09-01), Raab et al.

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