Internal-combustion engines – Combustion chamber means having fuel injection only – Using multiple injectors or injections
Patent
1999-06-30
2000-05-30
Miller, Carl S.
Internal-combustion engines
Combustion chamber means having fuel injection only
Using multiple injectors or injections
123501, F02B 300
Patent
active
060679557
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The invention is directed to improvements on a fuel injection device for internal combustion. In a fuel injection device of this kind, which is known from EP 0 657 642, the high-pressure fuel source is comprised of a high-pressure fuel pump, which delivers fuel from a low-pressure chamber into a high-pressure accumulation chamber, which is connected by way of pressure lines to individual injection valves that protrude into the combustion chamber of the engine to be supplied, wherein the common pressure storage system (common rail) is kept at a particular pressure level by means of a pressure control device. In order to control injection times and injection quantities, an electrically controlled control valve is provided to each of the injection valves and controls the high-pressure fuel injection with its opening and closing. The control valve in the known fuel injection device is embodied as a 3/2-way valve that connects a pressure conduit, which feeds at the injection opening of the respective injection valve, to the injection line leading from the high-pressure source or to a relief line into a low-pressure chamber.
Since the 3/2-way control valve in the known fuel injection device is actuated directly by the actuator of an electromagnet, the known fuel injection device has the disadvantage that the stroke of the valve member of the 3/2-way control valve and therefore the control effectiveness of the valve is limited. With the known fuel injection device, due to the use of an electromagnet, it is particularly difficult to achieve a high switching speed, especially if the intent is to use this device for the injection of a small pre-injection quantity and then a large main injection quantity via the fuel injection valve, therefore the control valve must consequently be opened and closed twice for this procedure.
OBJECTS AND SUMMARY OF THE INVENTION
It is a principal object of fuel injection device according to the invention that with the aid of the control valve, a greater through flow cross section can be produced, which permits a rapid opening and closing of the injection valve member, and a small electrically controlled pre-control valve is used to switch the control valve that makes the large through flow cross sections available. Since a piezoelectric drive mechanism is additionally used to actuate the valve member of the pre-control valve, an increased switching speed can be achieved.
Another object of the invention is to provide an increase in the switching speed for the production of a pre-injection is additionally achieved by means of the measure that the pre-control valve has two valve seats that are disposed in the course of the relief conduit of the working chamber and are alternatingly opened and closed with a single actuation of the pre-control valve member. As a result, without time loss due to the building up or attenuation of a field in an electromagnet and without the high energy requirement that would otherwise be required for this, an intermediary relief of the working chamber is achieved with a single excitation of the piezoelectric drive mechanism, which is only determined by the path that the precontrol valve member has to travel and by the actuation speed of the piezoelectric drive mechanism. Still another object of the invention provides that in connection with the very large cross section that can be controlled by the control valve, a very rapid switching of the control valve can thus be achieved and correspondingly small injection quantities can be controlled. Yet another object of the invention is that in order to be able to assume a different position that lies between the valve seats, by means of the property of the piezoelectric drive mechanism with its actuation mechanism, the main injection quantity can also be controlled in a highly precise manner.
BRIEF DESCRIPTION OF THE DRAWINGS
An exemplary embodiment of the injection is depicted in the drawings and will be explained in more detail in the description that follows.
FIG. 1 shows a com
REFERENCES:
patent: 3391680 (1968-07-01), Benson
patent: 4331434 (1982-05-01), Brunais
patent: 4546739 (1985-10-01), Nakajima
patent: 5647316 (1997-07-01), Hellen
patent: 5979410 (1999-11-01), Grieshaber
Greigg Edwin E.
Greigg Ronald E.
Miller Carl S.
Robert & Bosch GmbH
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