JP2950347B2 - Fuel injection nozzle - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel injection nozzle of a fuel injection device for injecting fuel into an internal combustion engine.

[0002]

2. Description of the Related Art As a conventional technique, Japanese Utility Model Laid-Open No.
A technique disclosed in Japanese Patent Application No. 970 is known. According to this technique, a sub-injection hole for injecting fuel is provided around an injection hole provided in a nozzle body, and carbon attached around the injection hole is removed.

[0003]

The injection nozzle is entirely exposed to the combustion gas. According to the above technique, carbon around the injection hole can be removed, but carbon attached between the injection hole and the pin is removed. Can not. And the injection nozzle is
Since the injection amount is controlled by controlling the flow path area between the injection hole and the pin, the substantial flow path area decreases if carbon adheres between the injection hole and the pin. This will be described with reference to a graph shown in FIG. 4. In the initial stage of using the injection nozzle, the relationship between the lift amount and the injection amount as shown by the solid line A was used.
As shown by the broken line C, the injection amount is reduced with respect to the lift amount. If carbon adheres between the injection hole and the pin, the fuel is squeezed particularly at the beginning of the injection, which has the disadvantage of deteriorating noise and increasing NOx.

[0004]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a fuel injection nozzle capable of maintaining its initial performance for a long period of time even when used for a long period of time.

[0005]

The fuel injection nozzle according to the present invention employs the following technical means. The fuel injection nozzle includes a nozzle body having an injection hole, and a nozzle needle slidably disposed in the nozzle body, and a pin at a tip portion disposed in the injection hole. The fuel supplied from the upstream of the seat portion and the valve seat is injected from between the injection hole and the pin by separating the seat portion from the valve seat of the nozzle body. The nozzle body has a sub-injection hole for inflowing the fuel guided downstream of the seat portion and the valve seat, and ejecting the inflowing fuel toward the pin. A pin large-diameter portion that overlaps in the hole and exits from the injection hole at the time of lift, and the inflow port of the sub-injection hole is an overlap between the pin large-diameter portion and the injection hole downstream of the valve seat and at the time of seating. The outlet of the sub-injection hole is provided upstream of the portion, and the outlet of the sub-injection hole is provided downstream of the overlapping portion of the pin large diameter portion and the injection hole when seated, and the total area of the holes of the injection hole is The pin is provided to be larger than the clearance area between the large diameter portion of the pin and the injection hole.

[0006]

When the seat portion of the nozzle needle is pulled up from the valve seat of the nozzle body, the fuel supplied upstream of the seat portion and the valve seat flows downstream of the seat portion and the valve seat. During the lift of the nozzle needle, while the pin large diameter portion and the injection hole overlap, fuel that has flowed downstream of the seat portion and the valve seat is mainly injected toward the pin through the sub-injection hole, Blows off carbon that adheres to the pin, preventing carbon from adhering to the pin. As the lift of the nozzle needle further increases and the large diameter portion of the pin comes out of the injection hole, the gap between the pin and the injection hole increases, and sufficient fuel is injected between the pin and the injection hole to ensure engine performance. it can.

[0007]

According to the fuel injection nozzle of the present invention, every time fuel is injected, the carbon adhering to the pin is blown off to prevent the carbon from adhering to the pin. A reduction in area can be prevented. As a result, the initial characteristics of the fuel injection nozzle can be maintained for a long time.

[0008]

Next, a fuel injection nozzle according to the present invention will be described with reference to an embodiment shown in the drawings. FIG. 1 to FIG. 4 show an embodiment of the present invention, and FIG. 2 is a sectional view of a fuel injection nozzle. The fuel injection nozzle 1 slidably holds the body 5 of the nozzle needle 4 within the guide cylindrical surface 3 of the nozzle body 2, and is provided at the tip (lower end in the drawing) of the nozzle needle 4. A pin 6 is disposed in an injection hole 7 formed at an end of the nozzle body 2. When the nozzle needle 4 is pushed upward in the figure by the fuel fed from the fuel injection pump (not shown) to the pressure receiving chamber 9 via the fuel passage 8, the seat portion 10 provided on the nozzle needle 4 is The fuel that is separated from the valve seat 11 and is pressure-fed to the seat portion 10 and the pressure receiving chamber 9 on the upper side of the valve seat 11 in the drawing passes between the pin 6 and the injection hole 7, and is outside the injection hole 7 (combustion chamber). Injected to.

FIG. 1 shows the tip of the injection nozzle 1. Downstream side of the seat portion 10 of the nozzle needle 4 (lower side in the figure)
Of the pins 6 provided in the fuel injection port 7 in the state where the seat portion 10 is in contact with the valve seat 11, a pin large diameter portion 6 a having a large diameter on the upstream side (upper side in the drawing); On the downstream side, a small diameter pin portion 6b having a small diameter is provided. The inside of the injection hole 7 is formed with a large-diameter portion 7a having a large diameter on the upstream side and a small-diameter portion 7b having a small diameter on the downstream side.
The clearance area A between the pin large diameter portion 6a and the hole large diameter portion 7a
And the gap area B between the pin small diameter portion 6b and the hole small diameter portion 7b is A <B. The relationship between the overlap margin C between the pin large diameter portion 6a and the hole large diameter portion 7a and the overlap margin D between the pin small diameter portion 6b and the hole small diameter portion 7b is C ≒ D. With this arrangement, the flow rate during the throttle period is determined by the gap area between the pin small diameter portion 6b and the hole small diameter portion 7b.

One or more sub-injection holes 12 are provided on the injection hole 7 side of the nozzle body 2. This sub-injection hole 12 is located downstream of the valve seat 11 and upstream of the injection hole 7,
2a, the outlet 12b is provided in the hole large diameter portion 7a downstream of the pin large diameter portion 6a, and the fuel guided downstream of the seat portion 10 and the valve seat 11 flows through the inlet 12a,
It is ejected from the outlet 12b toward the pin small diameter portion 6b. The position of the pin 6 to which the sub-injection hole 12 blows the fuel is provided at substantially the same height as the step 7c between the large-diameter portion 7a and the small-diameter portion 7b. The area of the sub-injection hole 12 (the total area when there are a plurality of holes) is determined by the pin small diameter portion 6.
b is larger than the gap area between the hole 7b and the small diameter portion 7b.

Next, the operation of the above embodiment will be briefly described. When the nozzle needle 4 is pushed up by the pressure of the fuel pressure-fed to the pressure receiving chamber 9 from the fuel pump, the seat portion 10 separates from the valve seat 11 and the seat portion 1
The fuel being pumped into the pressure receiving chamber 9 through the space between the valve 0 and the valve seat 11 is injected into the combustion chamber from between the injection hole 7 and the pin 6. When this fuel is injected, if the lift amount of the nozzle needle 4 is equal to or less than the overlap amount C or D, the fuel passes through the sub-injection hole 12 and collides with the pin small diameter portion 6b (see the arrow in FIG. 3). At this time, the fuel colliding with the pin small-diameter portion 6b blows off carbon adhering to the pin small-diameter portion 6b. When the lift amount of the nozzle needle 4 becomes larger than the overlap allowances C and D, the pin small diameter portion 6b moves from the hole small diameter portion 7b into the hole large diameter portion 7a, and the pin large diameter portion 6a Exit from inside. For this reason, the fuel has a large diameter portion 7a.
And a small gap between the pin 6 and the pin small-diameter portion 6b.
And the injection hole 7.

[Effects of the Embodiment] In this embodiment, as described above, every time the nozzle needle 4 is lifted, the fuel that has passed through the sub-injection hole 12 causes the carbon adhering to the pin small diameter portion 6b to adhere. Can be blown off, and as shown by the broken line B in the graph of FIG. 4, the initial characteristics (solid line A) at the time of new product can be maintained for a long time.

Second Embodiment FIGS. 5 and 6 show a second embodiment. FIG. 5 is a top view of the nozzle body 2 and FIG.
Is a sectional view thereof. In the present embodiment, the passage of the sub-injection hole 12 formed in the nozzle body 2 is provided tangentially to the pin small diameter portion (see the first embodiment). As described above, by providing the passage of the sub-injection hole 12 in a tangential direction to the pin small-diameter portion, the fluid friction of the fuel passing through the sub-injection hole 12 and colliding with the pin (see the first embodiment) causes the nozzle. By rotating the needle 4, fuel is sprayed on the entire circumference of the small diameter portion of the pin to efficiently remove carbon adhering to the pin.

[Brief description of the drawings]

FIG. 1 is an enlarged sectional view of a main part of a fuel injection nozzle.

FIG. 2 is a sectional view of a fuel injection nozzle.

FIG. 3 is an operation explanatory diagram for explaining the operation of the embodiment.

FIG. 4 is a graph showing a relationship between a lift amount of a nozzle needle and an injection amount.

FIG. 5 is a top view of the nozzle body.

FIG. 6 is a sectional view taken along line AA of FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Fuel injection nozzle 2 Nozzle body 4 Nozzle needle 6 Pin 7 Injection hole 10 Seat part 11 Valve seat 12 Sub injection hole

Claims (1)

(57) [Claims] 1. A nozzle body having an injection hole, a nozzle needle slidably disposed in the nozzle body, and a nozzle needle having a tip pin disposed in the injection hole, wherein a sheet of the nozzle needle is provided. A fuel injection nozzle that injects fuel supplied from the upstream of the seat portion and the valve seat from between the injection hole and the pin by separating a portion from a valve seat of the nozzle body. The fuel injection system further includes a sub-injection hole that inflows fuel guided downstream of the seat portion and the valve seat and ejects the inflowing fuel toward the pin, wherein the pin overlaps with the injection hole when seated, and the pin overlaps when lifted. A pin large-diameter portion that escapes from the injection hole, and the inflow port of the sub-injection hole is downstream of the valve seat and when seated.
At the overlapping portion between the pin large diameter portion and the injection hole.
Remote provided upstream, the outlet of the secondary injection hole, the said pin large diameter portion at the time of sitting than the overlapping portion of the injection hole provided on the downstream side, the total area of the holes of the injection holes, The pin large diameter portion and the jet
A fuel injection nozzle, wherein the fuel injection nozzle is provided to be larger than a gap area between the injection hole and the fuel injection hole .