Internal-combustion engines – Combustion chamber means having fuel injection only – Using multiple injectors or injections
Patent
1999-01-06
2000-01-25
Moulis, Thomas N.
Internal-combustion engines
Combustion chamber means having fuel injection only
Using multiple injectors or injections
123506, F02B 300, F02M 3704
Patent
active
060167866
DESCRIPTION:
BRIEF SUMMARY
PRIOR ART
The invention is based on a fuel injection system.In one such system, known from German Patent Application DE-A 36 44 257, a distributor injection pump is provided as the fuel injection pump, with a reciprocatingly driven and at the same time rotating pump piston, which upon its rotary motion and in its pumping stroke in each case supplies one of a plurality of injection lines, each leading to one fuel injection valve, with fuel brought to injection pressure. To subdivide the injection into a preinjection and a main injection, the electrically controlled valve, which is a magnet valve, is briefly opened, so as to relieve the pump work chamber and briefly reduce the fuel pressure attained. This means that a very fast-switching magnet valve is needed, which involves considerable effort and expense for its electrical control and for the construction of the valve. In particular, a special pressure valve is provided in the connection between the pump work chamber and the injection valve as well; it opens in the supply direction during high-pressure fuel pumping to the fuel injection nozzle and closes upon termination of the injection and is suitable for reducing pressure waves between the pressure valve and the fuel injection valve and in this range of keeping a constant static pressure sought during the intervals between injections. It is advantageous, in the case of a subdivided fuel injection with one preinjection and one main injection per operating stroke of the respective cylinder to be supplied in the internal combustion engine, to assure a constant static pressure in the intervals between injections.
ADVANTAGES OF THE INVENTION
By means of the embodiment according to the invention, it becomes substantially simpler to control an injection that is subdivided into a preinjection and a main injection. Because the interruption is structurally dictated by way of the cam shape, an electrical control with an intermediate opening and reclosure of the electrically controlled valve in order to interrupt the injection between the preinjection and the main injection, and the attendant effort and expense, are dispensed with. Nor does the electrically controlled valve need the high switching speed that is required for exact control of the interval between a preinjection and a main injection, and the electrically controlled valve can be considerably simpler and smaller especially than a very fast-switching valve.
BRIEF DESCRIPTION OF THE DRAWINGS
One exemplary embodiment of the invention is shown in the drawing and will be described in further detail in the ensuing description.
FIG. 1 is a basic illustration of a fuel injection pump which is controlled by a magnet valve, and
FIG. 2 shows a course of the cam path according to the invention, in the form of a cam rise curve over the rotary angle.
DETAILED DESCRIPTION
The embodiment according to the invention is realized, in the exemplary embodiment described below, in terms of a distributor injection pump of the kind schematically shown in FIG. 1. This is a distributor injection pump of the axial piston type, but the subject of the invention is also applicable to other fuel injection pumps, such as distributor injection pumps of the radial piston pump type, or individual pumps with only a single pump piston to supply a single cylinder of an internal combustion engine, or in-line pumps. Nevertheless, the injection is especially advantageously realizable in a distributor injection pump, because then to supply the injection valves only a single electrically controlled valve is required, and the distribution to the individual injection valves is done with the aid of the distributor. In the distributor injection pump of the type shown in FIG. 1, a pump piston 1 is provided, which is disposed displaceably and rotatably in a cylinder bore 2 and there on the face end encloses a pump work chamber 10. The pump piston is coupled, for instance via a spring not otherwise shown, to a cam disk 6, which has axially downward-pointing cams 5 embodied according to the in
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patent: 5343845 (1994-09-01), Fehlmann
Jonas Stephan
Rodriquez-Amaya Nestor
Greigg Edwin E.
Greigg Ronald E.
Moulis Thomas N.
Robert & Bosch GmbH
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