Fluid sprinkling – spraying – and diffusing – Fluid pressure responsive discharge modifier* or flow... – Fuel injector or burner
Patent
1995-08-01
1997-05-27
Weldon, Kevin
Fluid sprinkling, spraying, and diffusing
Fluid pressure responsive discharge modifier* or flow...
Fuel injector or burner
F02M 4500
Patent
active
056324472
DESCRIPTION:
BRIEF SUMMARY
PRIOR ART
The invention is based on a fuel injection for internal combustion engines nozzle. In an injection nozzle of this kind which is known for example from EP 0 568 845 A1, the leakage oil emerging from the guide play of the valve needle in the nozzle body flows through the opening in the intermediate disk into the spring chamber in the nozzle holder, which spring chamber is connected by means of a connecting stub to a leakage oil return line. In this process, in the region of the intermediate disk it passes through the axial guide play between the intermediate pressure element and the axial play between the pressure bolt of the first closing spring and the pressure ring, surrounding the said pressure bolt, of the second closing spring. In this known pressure transmission device of the injection nozzle, damping of the movement of the valve needle in its pretravel position occurs when the intermediate pressure element is in contact with its edge region with the pressure ring of the second closing spring and the latter is simultaneously in contact with its end side with the intermediate pressure disk. By means of the interruption, which is produced in this process, in the connection between the low pressure side of the valve needle and the pressure-relieved spring chamber, the opening and closing characteristic of the fuel injection nozzle is changed by damping as a result of the build up of pressure on the low pressure side. In the pretravel position of the valve needle, the space in the intermediate disk is in fact sealed off by the intermediate pressure disk so that the build up in pressure occurs there. Since the pressure surface of the intermediate pressure element is larger than the pressure surface of the valve needle, a force results which is opposed to the closing of the needle and which delays the closing. As a result, an entirely undesired emission of hydrocarbon occurs.
ADVANTAGES OF THE INVENTION
The fuel injection nozzle with the characterizing features of the invention has the advantage that rapid closing of the valve needle after the injection phase is ensured so that the emission behavior of the internal combustion engine is of a high standard. The proposed solution is cost-effective and operationally reliable.
By means of the measures disclosed claim 1 advantageous developments and improvements of the fuel injection nozzle specified in claim 1 are possible.
BRIEF DESCRIPTION OF THE DRAWINGS
Exemplary embodiments of the invention are illustrated in the drawing and are explained in greater detail below.
FIG. 1 shows, in longitudinal section, a fuel injection nozzle which opens in two pressure stages,
FIGS. 2 and 3 show a detail in the area of the pressure transmission device of the fuel injection nozzle according to FIG. 1 in the "pretravel" and "complete travel" positions,
FIG. 4 shows an intermediate pressure element in plan view,
FIGS. 5 and 6, FIGS. 7 and 8 and FIGS. 9 and 10 show alternative embodiments of the intermediate pressure element in cross-section and in plan view and
FIG. 11 shows a pressure transmission device of alternative design, in longitudinal section.
DETAILED DESCRIPTION OF THE EXEMPLARY EMBODIMENTS
The fuel injection nozzle has a nozzle holder 10 on which a nozzle body 15 is clamped tightly with a union nut 13 over an intermediate disk 14. The nozzle body 15 has an injection opening 18 and a valve seat 17 which is mounted in front of the latter and with which a valve needle 16 which is displaceably mounted in the intermediate body 15 interacts. The guide hole for the valve needle 16 is widened, as is customary, at one point to form a pressure space 19 in the area of which the valve needle 16 has a pressure shoulder 21, which pressure space 19 is connected via a channel 22 to a stub and 23 on the nozzle holder 10 for the connection of a fuel feed line. The fuel pressure which acts on the pressure shoulder 21 of the valve needle 16 pushes the valve needle 16 upwards counter to the stepped force profile of the arrangement, described below, of closing spring
REFERENCES:
patent: 4359191 (1982-11-01), Uchida
patent: 4768719 (1988-09-01), Straubel et al.
patent: 4962890 (1990-10-01), Shindo et al.
Greigg Edwin E.
Greigg Ronald E.
Robert & Bosch GmbH
Weldon Kevin
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