JPS6052310B2 - Throttle type fuel injection valve - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in a throttle type fuel injection valve for a diesel engine.

A throttle type fuel injection valve as shown in FIG. 1 is known as a fuel injection valve for a diesel engine.

The valve body 2 approaches and separates from the valve seat part 1 of the injection valve main body via the conical seal part 3, and when the pressure of fuel from a fuel injection pump (not shown) led to the oil sump 7 becomes high, the valve body 2 lifts upward, and fuel is injected from the nozzle hole 6.

During this injection process, when the valve body 2 lifts slightly and the seal part 3 separates, the fuel pressure in the valve chamber 9 immediately increases, and a small amount of fuel is released from the annular gap 8 between the nozzle hole 6 and the throttle part 4 of the valve body 2. A preliminary injection is performed prior to the main injection after the throttle part 4 has completely come out of the nozzle hole 6.

This preliminary injection starts relatively slow combustion,
The combustion that follows in the main injection develops smoothly, reducing combustion noise, improving exhaust composition, and increasing engine stability.

However, in the conventional fuel injection valve, the throttle part 4 and the nozzle hole 6 are parallel and the annular gap 8 is uniform, so as shown in FIG. If carbon 11 or the like adheres, preliminary injection may not be performed or the injection may become unstable until the tip of the throttle section 4 comes out of the nozzle hole 6 when the valve body 2 is lifted. . In such conditions, preliminary injection becomes impossible or unstable, and the fuel flow rate increases at the beginning of main injection, resulting in severe fuel ignition delay, increased combustion noise, and engine stability. Cause.

In order to solve this problem, the present invention forms a tapered surface on the throttle part and the nozzle hole of the valve body, which tapers with respect to the axis, so that the minimum width of the annular gap can be adjusted according to the lift of the valve body. To provide a throttle type fuel injection valve which is configured to increase the amount of fuel and maintain good preliminary injection at all times.

Embodiments of the present invention will be described below based on the drawings.
As shown in FIG. 3, the nozzle hole 6 and the throttle part 4 have a tapered surface 13 having the same inclination angle with respect to the axis.
are formed on the inner and outer walls, respectively. Therefore, the width of the annular gap 8 between the nozzle hole 6 and the throttle section 4 increases in proportion to the lift amount of the valve body 2.

As a result, as shown in FIG. 4, even if a carbon adhesion layer 14 is formed on the lower surface of the valve seat portion 1, the inner wall of the nozzle hole 6, and the outer wall of the throttle portion 4, as the valve body 2 lifts, the annular shape Since the width of the gap 8 increases, the fuel in the valve chamber 9 can be slightly ejected from the increased gap 8 even with a slight lift. Therefore, preliminary injection can be reliably performed prior to main injection in which the valve body 2 is sufficiently lifted.

In FIG. 5, the throttle part 4 is formed in a straight shape as in the past, and a tapered surface 13 is provided only on the inner surface of the nozzle hole 6. In this case as well, the annular gap 8 is adjusted according to the lift of the valve body 2. Since the amount of fuel is increased, a good preliminary injection can be performed.

Further, in FIG. 6, a tapered surface 13A is formed at the tip of the straight throttle portion 4, and together with the tapered surface 13 of the nozzle hole 6, an annular gap 8 is formed which increases as the lift increases.

In both of these embodiments, the tapered surface of the throttle portion 4 is omitted or made part of it, resulting in an advantage of improved manufacturability.

In the above embodiment, the same reference numerals are used for the same parts as in the prior art.

As described above, according to the present invention, at least the inner wall of the nozzle hole into which the throttle portion of the valve body is inserted is formed into a tapered surface, so that the annular gap between the throttle portion and the nozzle hole opens toward the combustion chamber side. The annular taper becomes narrower, making it difficult for carbon to adhere or become clogged.Also, even if carbon adheres to these areas and the annular gap between the throttle part and the nozzle hole becomes clogged when the valve is closed, the valve body As soon as the engine begins to lift, the minimum width of this annular gap increases, ensuring the injection of preliminary fuel and thus preventing long-term deterioration of combustion noise, engine stability or exhaust composition. becomes possible.

Further, by providing the tapered surface, the fuel flows smoothly through the annular gap, especially during preliminary injection, and the amount of adhesion of carbon and the like is reduced, further enhancing the above-mentioned effects.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a conventional device, and FIG. 2 is an enlarged operational view of the main parts. FIG. 3 is a sectional view showing an embodiment of the present invention, FIG. 4 is an enlarged operational view of the main part, and FIGS. 5 and 6 are sectional views showing other embodiments. 1...Valve seat part, 2...
...Valve body, 3... Seal part, 6...
Nozzle hole, 4...throttle portion, 7...valve chamber, 8...annular gap, 13...tapered surface.

Claims (1)

[Claims] 1. A throttle type fuel injection valve consisting of a valve body having a seal portion and a throttle portion, a valve seat portion on which the seal portion is seated, and a nozzle hole into which the throttle portion is inserted with a predetermined gap, A throttle type fuel injection valve characterized in that the inner wall of the tip of the nozzle hole outlet is formed into a tapered surface tapered with respect to the axis.