JPH0988772A - Fuel injection valve for internal combustion engine - Google Patents

Abstract

(57) Abstract: In a fuel injection valve to which assist air is supplied, backflow fuel is prevented from staying in the assist air supply system. SOLUTION: In an adapter 5 which is fitted and inserted in a holder 2 of a fuel injection valve 1, an assist air intake port is opened in an outer peripheral wall which is a fitting and insertion wall for the holder 2 to form two air nozzles 7a and 7b. On the other hand, by forming the assist air supply passages 4a and 4b penetrating the holder 2 and opening to the inner peripheral wall of the holder 2 and inserting the adapter 5 into the holder 2, the assist air supply passages 4a and 4b are inserted. And the air nozzles 7a and 7b are directly connected to each other.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel injection valve for an internal combustion engine, and more particularly, to a technique for preventing backflow of fuel to an assist air supply system in a fuel injection valve that aims to atomize fuel by assist air.

[0002]

2. Description of the Related Art Conventionally, a part of intake air is guided from the intake passage on the upstream side of a throttle valve as assist air to the vicinity of a nozzle hole of a fuel injection valve, and the assist air collides with the fuel spray injected from the fuel injection valve. It is known that the fuel is atomized by doing so to improve combustion, thereby improving fuel efficiency and exhaust gas properties (see Japanese Patent Laid-Open No. 10224/1993).

Conventionally, such a fuel injection valve has a structure as shown in FIG. Fuel injection valve 1 shown in FIG.
Is installed in the holder 2 and is attached to an intake port portion (not shown) with the vertical direction of the drawing as a substantially vertical direction. FIG.
The direction of penetrating the sheet of paper is the arrangement direction of the fuel injection valves 1. Fuel of a predetermined pressure supplied into the holder 2 via a fuel gallery not shown passes through the cylindrical filter 3 and is introduced into the fuel injection valve 1. Then, the valve body is lifted by the magnetic attraction force of the electromagnetic coil, so that the fuel is injected from the injection hole provided at the tip portion.

Further, as a structure for causing assist air to collide with the fuel spray injected from the injection hole, an assist air supply passage 4 whose one end is connected to an intake passage on the upstream side of the throttle valve connects the holder 2 to the holder 2. It penetrates and opens in the holder 2. An adapter (nozzle member) 5 in which an air nozzle is formed is fitted into the tip of the fuel injection valve 1, and an annular space surrounded by the reduced diameter portion 5 a of the adapter 5 and the inner circumference of the holder 2 introduces assist air. It is formed as a portion 6 (see FIG. 5), and the other end of the assist air supply path 4 faces the inside of the assist air introducing portion 6.

The adapter 5, as shown in FIG.
A hollow portion 5b into which the tip portion of the fuel injection valve 1 is inserted, and spray passages 5c, 5d through which the fuel spray from the fuel injection valve 1 passes are formed continuously with the hollow portion 5b. In the example shown in FIG. 4, the spray passages 5c and 5d are branched and extended in two directions in response to the fuel injection valve 1 injecting in two left and right directions.

Further, in the adapter 5, a pair of air nozzles 7a and 7b, one end of which faces the reduced diameter portion 5a and the other end of which faces the spray passages 5c and 5d, face each other around the axis of the injection valve. Formed, and the assist air supply path 4
The assist air introduced into the assist air introducing section 6 through the branching flow to the left and right in the assist air introducing section 6, and the spray passage 5c, the spray passage 5c, through the air nozzles 7a, 7b.
It jets out into 5d and collides with fuel spray.

[0007]

In the fuel injection valve having the above structure, when the engine is under a heavy load, the fuel flows back into the assist air introducing portion 6 through the air nozzles 7a and 7b, and the fuel is assisted. The accumulated fuel stays in the space below the air nozzle opening on the side of the anti-assist air supply passage of the air introduction portion 6, and when the accumulated fuel becomes a low load, it is supplied into the intake passage to over-rich the air-fuel ratio. However, there was a fear that the startability, drivability, and exhaust properties would deteriorate.

That is, since the air nozzle is not provided on the side opposite to the assist air supply path of the assist air introducing portion 6 and the assist air flows from both directions collide with each other, the assist air is accumulated. Stagnation occurs. For this reason, if the backflowed fuel enters the stagnation portion, it becomes difficult to discharge the fuel along with the flow of the assist air, and a large amount of fuel stays in the space portion below the air nozzle opening. It is a thing.

The present invention has been made in view of the above problems, and in a fuel injection valve provided with an assist air supply system, the backflow fuel is prevented from staying and the staying fuel is supplied to the engine. It is an object of the present invention to prevent the air-fuel ratio from becoming excessively rich due to such a situation.

[0010]

Therefore, a fuel injection valve for an internal combustion engine according to a first aspect of the present invention includes an air nozzle for ejecting assist air toward fuel injected from the fuel injection valve, and the assist for the fuel injection valve. A supply path for supplying air, and an assist air supply path that is directly connected to each of the air nozzles.

According to this structure, since the air nozzle and the assist air supply passage are directly connected to each other, it is possible to eliminate a space in which the fuel flowing back through the air nozzle is retained. In the invention according to claim 2, the fuel injection valve is 2
It is a directional injection valve, and two air nozzles are provided corresponding to each injection direction, and two assist air supply passages that are directly connected to the air nozzles are provided.

According to this structure, the assist air collides with the fuel injected in the two directions from the fuel injection valve to atomize the fuel, and the backflow of fuel from each air nozzle can be prevented from staying. According to a third aspect of the present invention, the fuel injection valve is internally provided in the holder and fixed to the engine, and the assist air supply passage extends through the holder to open in the inner wall of the holder. The air nozzle and the assist air supply path are directly connected to each other by inserting the nozzle member, in which the assist air intake port of the air nozzle opens to the outer peripheral wall, into the tip of the holder.

According to this structure, if the assist air supply passage is opened in the inner peripheral wall of the holder into which the nozzle member is inserted, corresponding to the assist air intake port of the air nozzle which is opened in the outer peripheral wall of the nozzle member, the nozzle is formed. By inserting the member into the holder, the air nozzle and the assist air supply path can be directly connected easily.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below. An embodiment is shown in FIGS. 1 and 2. The same elements as those in FIGS. 3 to 5 are designated by the same reference numerals and the description thereof will be omitted. Adapter (nozzle member) 5 shown in FIGS. 1 and 2
Has an outer circumference formed substantially uniformly with an outer diameter corresponding to the inner diameter of the tip of the holder 2.

Further, the assist air intake ports of the air nozzles 7a and 7b facing the respective spray passages 5c and 5d provided corresponding to the two-way injection of the fuel injection valve 1 are fitted into the holder 2. It is opened to the outer peripheral wall. on the other hand,
Two assist air supply passages 4a and 4b are formed through the holder 2, and these assist air supply passages 4a and 4b are formed.
The opening of each holder b on the inner peripheral wall side is aligned with the assist air intake of the air nozzles 7a and 7b.

The assist air supply passages 4a and 4b are provided.
Is configured by connecting an assist air supply pipe to a through hole that penetrates the outer circumference and the inner circumference of the holder 2. Here, with the adapter 5 inserted and supported in the holder 2, the assist air supply passage 4 opened in the inner peripheral wall of the holder 2.
By overlapping a and 4b with the assist air intake ports of the air nozzles 7a and 7b opening on the outer peripheral wall of the adapter 5, the assist air supply paths 4a and 4b and the air nozzle 7a,
7b are directly connected to each other, and the assist air supply path 4
Assist air supplied via a is ejected through the air nozzle 7a, and assist air supplied through the assist air supply passage 4b is ejected toward the fuel spray through the air nozzle 7b.

According to this structure, even if the fuel flows backward through the air nozzles 7a and 7b, there is no space for the fuel to stay, so that the stagnant fuel is supplied to the engine so that the air-fuel ratio becomes excessively rich. Can be prevented. Also,
By inserting the adapter 5 into the holder 2, the assist air supply paths 4a and 4b and the air nozzles 7a and 7b can be connected directly and easily.

In the above embodiment, the opening areas of the assist air supply paths 4a, 4b and the air nozzles 7a, 7b which are directly connected to each other greatly change at the fitting surface of the adapter 5. A configuration may be adopted in which the opening areas of the assist air supply passages 4a and 4b that are formed therethrough are reduced toward the downstream side so that the opening areas change smoothly.

[0019]

As described above, according to the fuel injection valve of the internal combustion engine according to the invention of claim 1, since the air nozzle and the assist air supply passage are directly connected to each other, the fuel flowing backward through the air nozzle is There is an effect that the space for staying can be eliminated, and thus the air-fuel ratio can be prevented from becoming excessively rich due to the supply of stagnant fuel to the engine, and the operability and exhaust properties of the engine can be kept good. .

According to the second aspect of the present invention, the assist air collides with each of the fuels injected in two directions from the fuel injection valve to atomize the fuel, and the fuel flowing back from each air nozzle stays. To avoid
There is an effect that it is possible to prevent the air-fuel ratio from becoming excessively rich due to accumulated fuel. According to the third aspect of the invention, there is an effect that the direct connection between the air nozzle and the assist air supply passage can be easily realized by inserting the nozzle member into the holder.

[Brief description of drawings]

FIG. 1 is a front partial cross-sectional view showing an embodiment of the invention.

FIG. 2 is a sectional view taken along line II-II of FIG.

FIG. 3 is a front partial cross-sectional view showing a conventional fuel injection valve.

4 is a sectional view taken along the line IV-IV in FIG.

5 is a cross-sectional view taken along line VV of FIG.

[Explanation of symbols]

 1 Fuel injection valve 2 Holder 4a, 4b Assist air supply path 5 Adapter (nozzle member) 5c, 5d Spray path 7a, 7b Air nozzle

Front page continuation (72) Inventor Kazuyoshi Mori 1370 Onna, Atsugi City, Kanagawa Prefecture Unisia Jecs Co., Ltd.

Claims (3)

[Claims] 1. An air nozzle for ejecting assist air toward fuel injected from a fuel injection valve, and a supply path for supplying the assist air to the fuel injection valve, which are directly connected to the air nozzle. A fuel injection valve for an internal combustion engine comprising an assist air supply passage. 2. The fuel injection valve is a two-way injection valve, two air nozzles are provided corresponding to each injection direction, and two assist air supply passages that are directly connected to the respective air nozzles are provided. The fuel injection valve for an internal combustion engine according to claim 1. 3. A structure in which the fuel injection valve is provided in a holder and fixed to an engine, wherein the assist air supply passage extends through the holder and opens in an inner wall of the holder. The air nozzle and the assist air supply path are directly connected to each other by inserting a nozzle member having an assist air intake port of the air nozzle that opens to the outer peripheral wall into the holder tip. A fuel injection valve for an internal combustion engine according to item 1.