Fuel injection nozzle for internal combustion engines

Details Fuel injection nozzle for internal combustion engines Fuel injection nozzle for internal combustion engines

1987-07-17

1988-09-06

Kashnikow, Andres

Fluid sprinkling, spraying, and diffusing

Fluid pressure responsive discharge modifier* or flow...

Fuel injector or burner

2395339, F02M 6120

Patent

active

047687193

DESCRIPTION:

BRIEF SUMMARY
BACKGROUND OF THE INVENTION

The invention relates to a fuel injection nozzle. In known injection nozzles of this generic type the shoulders which limit the initial lift of the valve needle are formed at the pressure pin of the first closing spring and at the pressure piece of the second closing spring. In this construction the tolerance range of the initial lift is determined by means of manufacturing tolerances at the nozzle body and the valve needle as well as at the pressure pin and the intermediate disk, so that it is necessary to adjust the initial lift by means of adapting the pressure pin. However, because of the large number of individual manufacturing tolerances and the deformation during assembly, the initial lift tolerance can be maintained only within a relatively large range of e.g. 0.05 mm, which is too large for many uses. With very small initial lifts, as are required for directly injecting engines, the tolerance range of the initial lift must be clearly smaller than the aforementioned magnitude given by way of example.


SUMMARY OF THE INVENTION

In contrast, the arrangement, according to the invention has the advantage that the tolerance range of the initial lift is determined only by means of manufacturing tolerances at the nozzle body and the nozzle needle. The initial lift can therefore be accurately measured and adjusted by means of grinding the valve needle. Moreover, dimensional tolerances or changes in other parts occurring during operation or during assembly no longer have an effect on the magnitude of the initial lift.
A construction which is particularly simple and suitable for manufacturing results if the shoulder limiting the initial lift is formed at the intermediate bush on its planar front side facing the nozzle body, which front side is pressed against an area of the upper, likewise planar front side of the nozzle body through the action of the second closing spring, which area is not covered by the intermediate disk.
The total lift of the valve needle can be adjusted in a simple manner if the intermediate disk is formed of two individual disks, that intermediate disk which adjoins the nozzle body having a larger borehole diameter than the other, and if the shoulder for limiting the total lift of the valve needle, which shoulder is formed at the intermediate disk, is formed at the area of the front side of the individual disk, which area is not covered by the other individual disk. In this construction, the total lift is determined by means of the thickness of the individual disk adjoining the nozzle body, so that only one individual disk of suitable thickness need be provided in order to obtain the desired total lift.
The intermediate bush can preferably be guided on a pressure peg of the valve needle, which also results in a guiding of the pressure pin of the first closing spring. In many cases, however, it can also be advantageous to construct the valve needle without pressure pegs and to guide the intermediate bush in the intermediate disk. In this arrangement the front side of the valve needle can be particularly simply treated and, moreover, pressure peg breakage is prevented at the valve needle.
The novel features which are considered as characteristic for the invention are set forth in particular in the appended claims. The invention itself, however, both as to its construction and its method of operation, together with additional objects and advantages thereof, will be best understood from the following description of specific embdiments when read in connection with the accompanying drawings.


BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 shows a fuel injection nozzle in longitudinal section;
FIG. 2 shows portions of the injection nozzle according to FIG. 1 in enlarged view and
FIG. 3 shows a variant of the construction, according to FIG. 1.


DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The injection nozzle according to FIG. 1 has a nozzle body 10, which is tightened on a retaining member 16 together with an intermediate disk 12 by means of a cap nut 14. A val

REFERENCES:
patent: 4168804 (1979-09-01), Hofmann
patent: 4285471 (1981-08-01), Eblen et al.
patent: 4403740 (1983-09-01), Eblen et al.
patent: 4566635 (1986-01-01), Trachte
patent: 4684067 (1987-08-01), Cotter et al.

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