JPS61164068A - Throttle type fuel injection nozzle - Google Patents

Abstract

PURPOSE:To restrain fuel injection amount during throttle period to reduce sufficiently idle noise by forming a jet of a nozzle body end of large and small diameter portions and forming a projection having a specified requirement in a throttle portion on a needle valve end. CONSTITUTION:A throttle type fuel injection nozzle is provided with a nozzle body 1 formed on the end with a jet 2 and a needle valve 5 lifted by fuel pressure. And the needle valve 5 is formed on the end with a cylindrical throttle portion 3 fitted in the inner peripheral surface of the jet 2 through a small gap. Said jet 2 is formed of an end side large diameter portion 2A and an oil reservoir 7 side small diameter portion 2B which have respectively cylindrical surfaces. And the throttle portion 3 has the same outer diameter as the inner diameter of said small diameter portion 2B at a position near the end and is formed with an annular projection 3A extending through the small diameter portion 2B during throttle period. Thus, fuel injection amount during the throttle period can be restrained to reduce sufficiently idling noises.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Application of i-Supplement The present invention relates to an improvement in a throttle-type fuel injection nozzle used in a diesel engine.

The conventional technology throttle 1M fuel injection nozzle suppresses the injection rate to an extremely low level and has a so-called throttle period installed at the beginning of injection to prevent a sudden rise in combustion pressure due to one ignition delay.
Specifically, the construction shown in Figures 3 and 4 of the culvert,
A needle valve 5 includes a cylindrical throttle part 3 that fits into the inner circumferential surface of the spout 2 at the tip of the nozzle body l through a minute gap, and a spout bottle part 4 that projects from the upper spout 2 and has a diameter of 91 steps. The tapered seat 106 has a structure formed at the front of the seat 106. The needle valve 5 has an oil layer 9 section 7F.
It lifts upward due to the fuel pressure of the EJ,
At this time, during the throttle period until the throttle section 3 is removed from the nozzle 2, fuel is injected through the slight opening of both, and the injection amount is suppressed to an extremely small amount. In addition, in the spray bottle g4d, the spray angle and injection direction k in the preliminary injection and the subsequent main injection during this throttle period. It has an aat that controls BIJ.

(For example, ``Jiho Engineering Zensho No. 5,'' published by Yamagaido Co., Ltd. in March 1980, '7#) Problems to be solved by the invention The throttle period until the main injection starts is 7 constant. In other words, the magnitude of idle noise has a correlation with the magnitude of the amount of fuel injected during the throttle period, and in order to reduce idle noise, it is necessary to reduce the amount of fuel as much as possible. . However, in the above-mentioned unconventional configuration, if the gap between the nozzle port 2 and the throttle part 3 is reduced to t-a degrees, it becomes impossible to secure the passage t-during the throttle period due to carbon adhesion, etc. There is a Kn that causes deterioration of characteristics such as a qualitatively delayed injection timing. Therefore, the above-mentioned gap is set to be relatively large in the case of w, which is not sufficient in terms of reducing idle noise.

Third Means for Solving the Problems In order to solve the above problems, in the throttle type fuel injection valve according to the present invention, the nozzle hole provided in the nozzle guide is connected to the large diameter part on the tip side and the oil filling part side. The small diameter part of the needle valve tip (a part of the D-circular a-shaped throttle part passes through the small diameter part of the nozzle at full blindness, and passes through the small diameter part during the throttle period. There are nine annular protrusions in total.

The injection amount is suppressed to a small amount during the period from when the working needle valve starts to lift until the throttle section leaves the small diameter section of the injection port, resulting in a nine throttle period.

During the 1% of this throttle period when the hollow protrusion M3 of the throttle section passes through the small diameter section, the injection amount is almost 0 and f
As a result, the total injection amount during the throttle period becomes very small. - If the seat is in poor condition, the annular protrusion is located within the large diameter portion, so a sufficient clearance can be secured between the inner peripheral surface of the nozzle and the throttle portion.

Embodiment FIG. 1 is an enlarged view of essential parts similar to FIG. 4 showing an embodiment of the present invention, and the same parts as those of the conventional system are given the same reference numerals.

In this fuel injection nozzle, the injection port 2 at the tip of the nozzle body l is formed by a large diameter portion 2A on the tip side and a small diameter portion 2B of the oil reservoir $7 (see Fig. 3), and each has a cylindrical surface. I am doing it. M9 Needle valve 5 is formed in the front enlarged part of the Ueda columnar throttle part 3, and the position of the tip of the throttle part 3 is, in detail, the needle valve 50 is housed in the large diameter part 2A circle in the seated state. Three annular protrusions are formed.
ing.

The outer circumference of this protrusion s3 has a relatively narrow cylindrical surface t,
Moreover, its outer diameter is set to be approximately equal to the inner diameter of the small diameter '1A2B. Here, the gap between the outer peripheral circle of the throttle part 3 and the inner peripheral surface of the small diameter part 2B is (a).

l1all in conventional throttle type fuel injection nozzle
It is almost the same as d, and on the other hand, the annular protrusion 3
Between the outer circumference of the human body and the inner circumference of the two large diameter parts
The gap (C) between B and the stepped portion 2C is set to be equal to or slightly larger than the above gap (A).

- Therefore, the relationship between the lift amount of the needle valve 5CD and the passage area is as shown by the 21st solid line.

That is, in the middle period of the throttle period (L, ), the small diameter portion 2Bt and the projection s3A pass.

The total WtllfO product is almost zero. The fuel qt injection t (approximately proportional to the passage surface, lateral integral value) during the throttle period (L, ) is much smaller than the conventional one shown in 91 points, and the idle noise is reduced. Myself. The tip side of the nozzle 2, where clogging due to carbon adhesion is likely to occur, has a large diameter @ 2 A! Since a sufficiently large gap is secured in the f-hole, even if it is built for a long period of time, there will be no substantial delay in the injection timing due to the t1 housing 9.

In the above embodiment, the upper and lower parts of the throttle part 3 are set to have the same diameter between the projections 3At, but they may have different diameters if necessary.

□ @uA effect　　　　　　　　　　　.

As is clear from the above explanation, the throttle-type fuel injection nozzle according to the present invention can sufficiently inject fuel during the throttle period without causing problems such as deterioration of injection characteristics due to carbon deposition. Figure 1 shows a reduction in the idle noise of a diesel engine.

[Brief explanation of the drawing]

FIG. 1 is an enlarged sectional view of the main parts of the throttle m fuel injection nozzle according to the present invention, FIG. The figure is a cross-sectional view of a conventional throttle-type fuel injection nozzle, and FIG. 4 is an enlarged cross-sectional view of the main parts thereof. l... Nozzle body, 2... Nozzle, 2A... Large diameter part. 2B°...Small diameter part, 3...Throttle part, 3A...
protrusion. 5... Needle valve. 2 people outside Figure 1 Figure 2 Need? Shibenri 7th

Claims (1)

[Claims] (1) A cylindrical throttle that has a nozzle body with a nozzle formed at its tip and a needle valve that is lifted by fuel pressure, and that is fitted to the tip of the needle valve with the inner peripheral surface of the nozzle through a small gap. In the throttle type fuel injection nozzle, the injection port is formed of a large diameter part on the tip side and a small diameter part on the oil reservoir side, and the inner diameter of the small diameter part is formed in a part of the throttle part. 1. A throttle-type fuel injection nozzle, characterized in that an annular protrusion is formed having a diameter substantially equal to the diameter of the diameter of the fuel injection nozzle and passing through the small diameter portion during the throttle period.