JPS61182459A - Fuel injecting valve - Google Patents

Abstract

PURPOSE:To enable regulation of opening of nozzle needle through one action, by a method wherein, in a fuel injection valve which is provided with 2 springs for regulating opening of a valve and capable of intermittently injecting fuel, the 2 springs are disposed so as to function in series to the nozzle needle. CONSTITUTION:Nozzle body 2 is secured to the one end of a nozzle holder 1 through threaded joining of a retaining nut 4, a furst and second springs 6 and 8 are contained in series with the nozzle holder 1 with an intermediate spring seat 7 therebetween. The one end of the first spring 6 is brought into contact with an intermediate spring seat surface 7a, and the other end is brought into contact with a pressure pin 5 to press a nozzle needle 3. The one end of a second spring 8 is brought into contact with an intermediate spring seat surface 7b, and the other end is brought into contact with an opening valve pressure regulating screw 10. This enables simultaneous variation of the spring constants of the two springs 6 and 8 through rotating control of the opening valve pressure regulating screw 10, and permit arbitrary variation of injecting particularity through proper selection of the spring constants of the springs 6 and 8.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a fuel injection valve, and in particular, the rise of the fuel flow rate at the beginning of fuel injection is sharpened by using a plurality of valve opening pressure adjustment springs. The present invention relates to a fuel injection valve for a diesel engine, which is further characterized in that a needle lift amount can be obtained in accordance with the load.

(Prior art) As a conventional fuel injection valve of this type,
No. 9568, Japanese Utility Model Application Publication No. 56-47254, and others are disclosed.

(Problems to be Solved by the Invention) In these conventional devices, two springs are arranged so that they function in parallel, and the set load of each spring is adjusted independently, so it is difficult to adjust the set load. There are problems in that it is time consuming and requires a large number of parts.

(Means for Solving the Problems) The present invention provides a fuel injection system in which fuel is intermittently injected by opening and closing a nozzle hole provided in a nozzle body using a nozzle needle slidably fitted into the nozzle body. The valve includes a first spring, a second spring, an intermediate spring seat, a set load adjusting member, and an initial lift adjusting rod, and the first spring is attached to one end of the nozzle needle in the valve closing direction. The first spring is negatively biased in the compression direction by the second spring via the intermediate spring seat, and the second spring is biased negatively by the set load adjusting member, so that the nozzle needle is While adjusting the valve opening pressure, the second
The valve opening speed of the nozzle needle is changed by disposing an initial lift adjustment rod facing the spring side end face of the nozzle needle with a predetermined gap therebetween.

(Function) According to the present invention, since the first spring and the second spring are arranged to function in series with the nozzle needle, the opening adjustment of the nozzle needle can be performed by adjusting the set load adjusting member. It only needs to be done once, and since the set value of the predetermined gap between the end face on the second spring side of the intermediate spring seat and the opposing initial lift adjustment rod can be easily adjusted, the valve opening speed of the nozzle needle can also be adjusted. Easy to set up.

(Example) The present invention will be explained below based on examples.

1 to 3 relate to a first embodiment of the present invention, and FIG. 1 is a sectional view showing the overall structure of a fuel injection valve;
Fig. 2 is a needle lift characteristic diagram showing how the needle lift amount changes with respect to the nozzle chamber pressure of the fuel injection valve in Fig. 1, and Fig. 3 is a fuel injection characteristic diagram showing the fuel injection characteristics of the fuel injector in Fig. 1. It is.

As shown in FIG. 1, the fuel injection valve of the first embodiment has a nozzle body 2 attached to one end of a nozzle holder l by a retaining nut 4.
The first spring 6 and the second spring 8 are arranged in series within the nozzle holder 1 with the intermediate spring seat 7 included.

The first spring 6 has one end in contact with the intermediate spring seat surface 7a and the other end in contact with the pressure pin 5 to press the nozzle needle 3, and the second spring 8 has one end in contact with the intermediate spring seat surface 7b. The other end is in contact with the valve opening pressure adjustment screw 10.

The valve opening pressure adjustment screw 10 is threadedly engaged with a screw provided at the other end of the nozzle holder 1, and is fixed with a set screw 11 after adjusting a predetermined valve opening pressure, and the initial lift adjustment rod 9 is adjusted to the valve opening pressure. After engaging with a screw provided on the adjustment screw 10 to adjust a predetermined gap f provided between the end surface 9a and the end surface 7c of the intermediate spring seat 7, it is fixed by the set screw 12.

Next, the operation of the first embodiment will be explained.

High-pressure fuel pumped from a fuel injection pump (not shown) in FIG.
The nozzle needle 3 is pushed up and separated from the valve seat 2c.

On the other hand, when the nozzle needle 3 is seated, it is pressed and sealed against the valve seat 2c by the first and second springs 6.8. The other end 7c is pushed up by the lift amount 11 of the intermediate spring seat 7 in the figure, and the initial lift adjustment rod 9
When the second spring 8 comes into contact with the other end 9a, it can no longer be compressed.

Further, the nozzle needle 3 rises and the maximum needle lift amount i! 2, only the first spring 6 is further compressed and the pressing force of the nozzle needle 3 is applied only by the first spring 6.

At this time, if the first and second spring constants of the springs that press the nozzle rudder are respectively set to 2, then
Needle lift amount Q, 1. + in = in + , kg
/ (k+ +kz), Ill'~12 becomes ni=. Therefore, the needle lift amount relative to the nozzle chamber pressure is given as shown in FIG.

In other words, by selecting two appropriate spring constants of 2, it is possible to achieve a fast rising injection rate during initial injection.
During main injection, each injection rate can be obtained in accordance with the load, and as a result, combustion can be significantly improved. FIG. 3 shows the fuel injection characteristics when using the fuel injection valve of the present invention.

4 and 5 relate to the second embodiment,
FIG. 4 is a sectional view showing the structure of the main part, and FIG. 5 is a plan view of the main part as seen from the direction A in FIG.

Focusing on the differences from the first embodiment, the second embodiment has a lever 13 integrally attached to the initial lift adjustment rod 9, and the lever 13 is moved in the direction of the arrow in FIG. The initial lift adjustment rod 9 can be moved and adjusted in the central axis direction by using a threaded portion 9a cut in the lift adjustment rod 9.

According to the second embodiment, since the predetermined gap 11 can be adjusted from the outside depending on the operating conditions while the injection valve is in operation, combustion can be further improved depending on the operating conditions of the engine.

Note that the means for operating the lever 13 may be mechanical or electrical. Further, the adjustment of the predetermined gap 11 can be modified in various ways other than those shown in this embodiment.

FIG. 6 is a sectional view showing the structure of the main part of the third embodiment.

Focusing on the differences, the third embodiment uses a shim 14 as a set load adjustment member instead of the valve opening pressure adjustment screw, and by doing so, it is possible to further reduce the size and weight. can.

(Effects of the Invention) As explained above, according to the present invention, the opening pressure of the nozzle needle can be adjusted only once, and the set value of the predetermined gap at the tip of the initial lift adjustment lot can be easily adjusted. This has the excellent effect that the valve opening pressure and valve opening speed of the nozzle needle can be adjusted extremely easily and accurately.

Furthermore, since the number of parts can be reduced, the device can be made smaller and lighter.

[Brief explanation of drawings]

1 to 3 relate to a first embodiment of the present invention, in which FIG. 1 is a sectional view showing the overall structure of a fuel injection valve, and FIG.
The figure is a needle lift characteristic diagram showing changes in the amount of needle lift with respect to the nozzle chamber pressure of the fuel injection valve in Figure 1, and Figure 3 is a fuel injection characteristic diagram showing the fuel injection characteristics of the fuel injector in Figure 1. . 4 and 5 relate to the second embodiment,
Figure 4 is a sectional view showing the structure of the main part, Figure 5 is A in Figure 4.
It is a top view of the main part seen from the direction. FIG. 6 is a sectional view showing the structure of the main part of the third embodiment. 2... Nozzle body, 2d... Nozzle hole, 3... Nozzle needle, 6... First spring, 7... Intermediate spring seat, 8... Second spring, 9... - Initial lift adjustment lot, 10° 14... Valve opening pressure adjustment screw and shim forming the set load adjustment member, II... Predetermined gap. Figure 1 Figure 2 Nostle! Pressure 3rd figure 4th line Ils? M → Figure 4. Figure 5 and Figure 6

Claims (1)

[Claims] In a fuel injection valve that intermittently injects fuel by opening and closing a nozzle hole provided in the nozzle body by a nozzle needle slidably fitted into the nozzle body, the fuel injection valve includes a first spring and a second spring. and an intermediate spring seat, a set load adjustment member, and an initial lift adjustment rod, the first spring is negatively biased toward one end of the nozzle needle in the valve closing direction, and the first spring is
The spring is biased in a compression direction by the second spring via the intermediate spring seat, and the second spring is biased negatively by the set load adjustment member to adjust the nozzle needle valve opening pressure. , a fuel injection system characterized in that the valve opening speed of the nozzle needle is changed by arranging an initial lift adjustment rod facing the end surface of the intermediate spring seat on the second spring side with a predetermined gap therebetween. valve.