Internal-combustion engines – Charge forming device – With fuel pump
Patent
1995-03-01
1997-03-04
Miller, Carl S.
Internal-combustion engines
Charge forming device
With fuel pump
123458, 251282, F02M 3704
Patent
active
056069537
DESCRIPTION:
BRIEF SUMMARY
PRIOR ART
The invention is based on a fuel injection device of an internal combustion engine. In a fuel injection device of this kind, known from DE-A1-37 31 240, the pump plunger is driven in reciprocation by means of a camshaft of an internal combustion engine. As a housing for the fuel injection device with the pump plunger, the pump cylinder and the injection valve an integrally formed housing is provided and this is connected directly to the cylinder head for the associated internal combustion engine. In this arrangement, the housing part bearing the exchangeable injection nozzle, together with the spring space of the injection valve, is arranged obliquely to the axis of the pump plunger. From the pump working space, a fuel passage leads directly to a solenoid valve, by means of which the phase of high-pressure generation in the pump working space is controlled. In this configuration, the space which is supplied with fuel under injection pressure during the pump plunger delivery stroke is additionally enlarged by the fuel passage leading to the solenoid valve and by an adjoining valve antechamber which is bounded by the valve seat of the solenoid valve in the closed position of the latter. This relatively large dead space reduces the efficiency and the accuracy of injection of the fuel injection device. At the same time, moreover, a relatively large installation space is required for the fuel injection device.
ADVANTAGES OF THE INVENTION
In contrast, the fuel injection device according to the invention has the advantage that the high-pressure volume is considerably reduced and, at the same time, that a fuel injection device of more compact design is achieved.
The invention has an advantage that the volume of the fuel passage between the pump cylinder and the valve seat can, in addition, be kept very small. If the valve is designed as a sliding valve with a piston slide this volume is reduced further. A continuous connection between the fuel passage and the pump working space results in only Slight enlargements of the cylinder space which is provided for the pump working space. The provisions set forth herein provide reliable guidance of the valve member of the solenoid valve while at the same time keeping the high-pressure dead space within the fuel passage small. One configuration set forth advantageously results in an economical manufacture by virtue of the fact that the valve member of the solenoid valve is coupled non-positively to the armature of the solenoid valve. Exact centering of the solenoid-valve body and the pump body is thus rendered unnecessary. It is furthermore advantageously achieved that overshooting of the magnet armature upon opening of the solenoid valve is avoided. A further development is advantageously achieved in that smaller fluctuations in operating times occur because the disturbing forces caused by pressure fluctuations in the fuel feed, particularly during opening, are smaller. The shape of the piston-like part of the valve member here results in a high degree of freedom from reaction due to fuel pressures acting on the valve member. Another configuration provides an easy-to-service and easy-to-assemble construction with good accessibility to the solenoid valve. Tolerances involved in the fitting of the fuel injection device on the cylinder head of the internal combustion engine are easily compensated for. Another configuration provides a compact construction in which it is possible to provide a smaller return spring for the pump plunger since an additional restoring force in the direction of the drive of the pump plunger during the delivery stroke of the pump plunger is achieved. In particular, a higher contact force is obtained at the end of the pump plunger delivery stroke.
DRAWING
Two exemplary embodiments of the invention are depicted in the drawing and explained in detail in the description which follows.
FIG. 1 shows a longitudinal section through the pump cylinder and the injection valve of the fuel injection device of a first exemplary embodiment,
FIG. 2
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Drummer Eugen
Kronberger Maximilian
Sattmann Helmut
Strahberger Herbert
Weisz Gerhard
Greigg Edwin E.
Greigg Ronald E.
Miller Carl S.
Robert & Bosch GmbH
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