Fuel injection nozzle for internal combustion engines

Fluid sprinkling – spraying – and diffusing – Terminal outlet formed between parts mounted for relative... – Spray fluid pressure responsive discharge modifier

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Details

2395333, 23953312, F02M 6108, F02M 6116

Patent

active

047307854

DESCRIPTION:

BRIEF SUMMARY
BACKGROUND OF THE INVENTION

The invention relates to a fuel injection nozzle for internal combustion engines.Injection nozzles of this type have the advantage that the opening stroke of the valve needle is performed in a damping manner. By a corresponding coordination of the throttle passage and a return spring of the cap it can be achieved that the dampening in certain ranges of the operating performance graph is only effective over a partial stroke of the valve needle. The pressure piece which is displaceably mounted in the bottom of the cap transmits the fuel pressure directly to the piston during a prestroke and through this piston to the valve needle. Thereby, it is achieved that a prestream of a sufficiently large fuel amount is injected at the start of each injection operation.
In a known injection nozzle of this type (DE-Al 33 07 671) the pressure piece has the same diameter as the piston which is connected with the valve needle. In this embodiment it is easy to work the bore in the cap, however the prestroke of the valve needle performs practically undampened. In many cases this may undesirably influence the dampening effect of the subsequent partial stroke or may result in certain ranges of the operating performance graph in an unfavorable ratio of the preinjection amount with respect to the main injection amount.


SUMMARY OF THE INVENTION

It is an object of the present invention to provide a fuel injection nozzle in which the prestroke of the valve needle is performed at least partially dampened in the lower speed and load range. By the adjustment of the diameter of the pressure piece and the piston to the throttle passage which leads into the dampening chamber (bearing play of the pressure piece and the piston) it can be achieved that the total opening stroke of the valve needle is limited to the magnitude of the prestroke during the idle running of the engine. By a corresponding dimensioning of the return spring of the pressure piece and its mounting slot it can be achieved that the pressure piece does not reach its initial position in the injection intervals when it engages on the piston, so that the prestroke also operates at least partially undampened. Such an injection operation may be particularly advantageous with high speeds and during a full load for a rapid injection of a large amount of fuel.
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 embodiments when read in connection with the accompanying drawing.


BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an elevated sectional view of the first exemplified embodiment in a longitudinal section;
FIG. 2 a partial longitudinal section through the second exemplified embodiment; and
FIGS. 3, 4 and 5 illustrate functional graphs of the injection nozzles illustrated in FIGS. 1 and 2 respectively.


DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The injection nozzle shown in FIG. 1 has a nozzle element 10 which is clamped to a nozzle support 14 by means of a screw cap 12. A socket 16 is provided between the nozzle element 10 and the nozzle support 14, which has an inwardly directed collar 18 which socket separates a chamber 20 from a chamber 22. A valve seat 24 is formed in nozzle element 10 and a valve needle 26 is displaceably mounted, whose stuffing cone 27 is pushed by a locking spring 28 against the valve seat 24. The locking spring 28 is supported on nozzle element 10 and engages by means of a flange part 30 a support disk 32 which in turn is supported on a shoulder 34 of the valve needle.
The nozzle support 14 has a feeding bore 36 which discharges into chamber 20 which is connected with chamber 22 by means of bores 38,39 in collar 18. From there a bore 40 in nozzle element 10 feeds into an annular chamber 42 which is formed between the central b

REFERENCES:
patent: 4531676 (1985-07-01), Seifert et al.
patent: 4572434 (1986-02-01), Seifert

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