JPH0510503B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a fuel injection valve for an internal combustion engine, and more particularly to the structure of a swirl generating section that gives a swirling flow to the injected fuel of the fuel injection valve.

[Conventional technology]

It is known that in the fuel injection valve of an internal combustion engine, by giving the injected fuel a swirling flow, the fuel is sufficiently diffused into the combustion chamber and the atomization of the fuel is promoted, improving the performance of the engine. It is being In order to give a swirling flow to the injected fuel with the fuel injection valve, as shown in FIG. 1 spiral groove 4
It is known that this can be achieved by providing a swirl generating section 5 in which a
Publication No. 77312, Publication of Utility Model Publication No. 53-58223, Japanese Patent Application Publication No. 1983
- Publication No. 2457).

[Problem to be solved by the invention]

However, in a fuel injection valve having such a conventional structure, a swirl generating section 5 that gives a swirling flow to the fuel is required.
The clearance between the needle valve 1 and the nozzle body 2 is kept constant with respect to the opening degree of the needle valve 1, so the swirl strength depends to some extent on the clearance and the shape of the helical groove 4, etc., regardless of the operating state of the engine. It will be decided. Therefore, if the swirl strength is adapted to the engine operating range of low speed and low oil injection amount (low load), on the high speed side, the penetration force (straight line force) of the fuel toward the nozzle hole 6 side will be impeded by the swirl. ,
There is a possibility that a problem of performance deterioration may occur, such as not being able to supply a sufficient amount of fuel to the combustion chamber.

On the other hand, if the swirl strength is adapted to the engine operating range of high speed and high oil injection amount (high load), the swirl strength will be insufficient at low speeds and the atomization of the spray will not progress, resulting in poor startability and There is a possibility that a problem may arise in which performance is degraded due to generation of a large amount of smoke.

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention aims to change the swirl strength depending on the operating state of the engine, and to cause swirl generation to contribute to improving the performance of the engine in all operating ranges.

[Means to solve the problem]

To achieve this object, a fuel injection valve for an internal combustion engine according to the present invention includes a needle valve movably disposed within a nozzle body having a nozzle hole for injecting fuel;
A fuel injection valve for an internal combustion engine that opens and closes a fuel passage leading to the injection hole by moving the needle valve,
A flow rate adjusting portion consisting of first tapered surfaces facing each other is provided on the outer circumferential surface of the needle valve forming the fuel passage and a part of the inner surface of the nozzle body, and the first tapered surface on the needle valve side includes a spiral groove. A swirl generating groove is formed, and a seal portion is formed downstream of the first tapered surface on the outer circumferential surface of the needle valve and the inner surface of the nozzle body, and includes a second tapered surface that can be brought into close contact with each other.

[Effect]

In such a fuel injection valve, a portion of the fuel passing through the clearance between the first tapered surface on the needle valve side of the flow rate adjustment section and the first tapered surface on the inner surface side of the nozzle body flows along the swirl generation groove. This gives the injected fuel a swirling flow. Here, since the flow rate adjustment parts are formed on the first tapered surfaces facing each other, the size of the clearance of the flow rate adjustment parts is determined by the lift amount of the needle valve. Therefore, the lift amount of the needle valve is small in the low speed and low load range of the engine (during low injection amount).
In this case, the clearance becomes smaller and most of the fuel passes through the swirl generating groove, giving a strong swirl.

Furthermore, in a high speed, high load range (at the time of high injection amount), the lift amount of the needle valve increases, so the clearance increases and the proportion of fuel passing through the swirl generation groove decreases. As a result, the swirl is weakened to ensure the necessary penetration force, and a sufficient amount of fuel is supplied via the flow rate adjustment section.

〔Example〕

Preferred embodiments of the fuel injection valve for an internal combustion engine according to the present invention will be described below with reference to the drawings.

2 to 4 show a fuel injection valve for an internal combustion engine according to an embodiment of the present invention. In the figure, 10 indicates a nozzle body, and a nozzle hole 11 for injecting fuel is formed at the tip of the nozzle body 10. A needle valve 12 is slidably inserted into the nozzle body 10 , and a fuel passage 13 communicating with the nozzle hole 11 is formed between the needle valve 12 and the inner surface of the nozzle body 10 .
The fuel passage 13 is connected to a second tapered surface 14a formed at the lower part of the inner surface of the nozzle body 10 and the needle valve 12.
A second tapered surface 14b formed on the outer peripheral surface of the tip of
It is opened and closed by a seal portion 15 consisting of.

When the second tapered surfaces 14a and 14b are in close contact with each other, the flow of fuel supplied from the fuel passage 13 is blocked. A clearance is formed in the seal portion 15 by lifting the needle valve 12, so that fuel from the fuel passage 13 is injected from the nozzle hole 11.

The needle valve 12 forming the fuel passage 13 and a part of the inner surface of the nozzle body 10 are provided with a flow rate adjusting section 1 consisting of first tapered surfaces 16 and 17 facing each other.
8 is provided. The flow rate of fuel flowing through the flow rate adjustment section 18 is adjusted according to the lift amount of the needle valve 11.

Of the first tapered surfaces 16 and 17, the first tapered surface 16 on the needle valve 12 side has a swirl generation groove 19 formed of a helical groove. The swirl generation groove 19 extends in a spiral shape from the upper end to the lower end of the first tapered portion 18 .

In addition, in this embodiment, the swirl generation groove 1
9 is formed on the needle valve 12 side, but may be formed on the inner surface side of the nozzle body 10. However, considering the groove machining surface, the nozzle body 10
Since it is difficult to process the inner surface, it is desirable to form it on the needle valve 12 side as in this embodiment.

The operation of the fuel injection valve configured as described above will be described below.

First, regarding the provision of a swirling flow to the injected fuel, that is, the generation of swirl, when the fuel is pumped through the fuel passage 13, the fuel passes through the swirl generation groove 19, and the pressure causes the needle valve to open. 1
2 is lifted upwards. Due to this lift of the needle valve 12, a clearance extending in the circumferential direction is formed between the first tapered surfaces 16 and 17.

The fuel will pass through this clearance, but since the swirl generation groove 19 is formed in the first tapered surface 16 on the needle valve 12 side, some of the fuel passing through the swirl generation groove 19 will cause the fuel to swirl. A flow is applied, and the fuel that has passed through the flow rate adjustment section 18 is injected from the nozzle hole 11 while swirling.

In this fuel injection, when the engine is in a low speed and low load range (low injection amount), the amount of fuel pumped is small, so the pressure acting on the needle valve 12 is also small, and the lift amount of the needle valve 12 is small. is small.
Therefore, the clearance in the flow rate adjustment section 18 is also formed small, and the ratio of the amount of fuel passing through the swirl generation groove 19 to the total amount of fuel passing through the flow rate adjustment section 18 becomes large. Therefore, the flow rate adjustment section 1
The fuel passing through the groove 8 is strongly controlled by the swirling flow caused by the swirl generating groove 19 and is given a strong swirl.

Furthermore, when the engine is in a high speed, high load range (at the time of high injection amount), the amount of fuel pumped is large, so the pressure in the flow rate adjustment section 18 becomes large, and the lift amount of the needle valve 12 becomes large. . Therefore, a large clearance is formed in the flow rate adjustment section 18,
The ratio of the amount of fuel passing through the swirl generation groove 19 to the amount of all the fuel passing through becomes small, and the swirl given to the injected fuel is weakened. When the swirl is weakened, the penetration force (straight force) of the fuel passing through the flow rate adjustment section 18 is ensured to a large extent, so that a sufficient amount of fuel is supplied to the nozzle hole 11 and injected in a predetermined short time.

〔Effect of the invention〕

According to the present invention, a flow rate adjustment portion consisting of first tapered surfaces facing each other is provided on the outer circumferential surface of the needle valve and a part of the inner surface of the nozzle body forming the fuel passage, and the first tapered surface on the needle valve side A swirl generating groove consisting of a spiral groove is formed on the surface, and a sealing portion consisting of a second tapered surface that can be brought into close contact with each other is formed downstream of the first tapered surface on the outer peripheral surface of the needle valve and the inner surface of the nozzle body. Therefore, the strength of the swirl can be continuously changed according to the lift amount of the needle valve, that is, the operating state of the engine.

Therefore, in a low speed and low load range, a strong swirl is given to the injected fuel to promote atomization of the fuel, improving the startability of the engine and reducing the smoke in the low range. Furthermore, at high speeds and high load ranges, it becomes possible to weaken the swirl and supply a sufficient amount of fuel, which can contribute to improving the output of the engine.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view of a conventional fuel injection valve, FIG. 2 is a longitudinal sectional view of a fuel injection valve for an internal combustion engine according to an embodiment of the present invention, and FIG. 3 is an enlarged view of the device shown in FIG. 2. The vertical cross-sectional view, FIG. 4, is a cross-sectional view taken along the line - in FIG. 10... Nozzle body, 11... Nozzle hole, 12...
...Needle valve, 13...Fuel passage, 14a, 14
b...Second tapered surface, 15...Seal portion, 1
6, 17...First tapered surface, 18...Flow rate adjustment section, 19...Swirl generation groove.

Claims (1)

[Claims] 1. In a fuel injection valve for an internal combustion engine, a needle valve is movably provided in a nozzle body having a nozzle hole for injecting fuel, and the fuel passage is formed by movement of the needle valve for an internal combustion engine. A flow rate adjusting portion consisting of first tapered surfaces facing each other is provided on the outer peripheral surface of the needle valve and a part of the inner surface of the nozzle body, and a swirl generating groove consisting of a helical groove is provided on the first tapered surface on the needle valve side. and a seal portion consisting of a second tapered surface that can be brought into close contact with each other is formed downstream of the first tapered surface on the outer circumferential surface of the needle valve and the inner surface of the nozzle body. valve.