JP2000213439A - Fuel injection system of internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize a fuel injection system of internal combustion engine which is excellent in atomization characteristic at low fuel pressure and excellent in fuel flow linearity. SOLUTION: In this fuel injection system of internal combustion engine in which a nozzle hole 2 of a swirl nozzle 1 directly opens into a cylinder and fuel is directly injected into the cylinder, a fuel guide 3 diametrally enlarging along a injecting direction is provided at a downstream side of the nozzle hole 2 of the swirl nozzle 1. An assist air outlet 5 of an assist air passage 6 opens to inner surface of the fuel guide 3, a squish part is provided on a surface opposite to a piston of a cylinder head, and an air introducing port of the assist air passage 6 opens to the squish part.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a fuel injection valve in a fuel injection device for an internal combustion engine, and more specifically, to improve atomization of spray by mixing air into fuel injected from an injection hole, thereby improving HC. An object of the present invention is to provide a fuel injection device for an internal combustion engine capable of improving combustion such as reduction and fuel consumption.

[0002]

2. Description of the Related Art Japanese Unexamined Patent Publication No. Hei 9-195894 discloses an example of the prior art in which atomization is achieved by using air. This is a hall-type fuel injection nozzle, in which an air introduction port is provided for a fuel injection port, and air is introduced by an ejector effect of fuel. In particular, the air passage intersects the fuel passage at an acute angle, has an intersection with the air passage near the fuel outlet, and the air inlet is at the tip of the injector. is there.

[0003]

However, in such a conventional air-based atomizing injection valve, air is introduced into the injection hole, and an air passage is provided in the fuel metering section. The problem is that the fuel metering becomes unstable. In particular, when the fuel injection amount is large and the air introduction amount is large, and when the fuel injection amount is small and the air introduction amount is small or almost not introduced, the fuel injection rate (mm
³ / ms), and the injection amount cannot be limited in time. In addition, it is necessary to provide an air inlet having a diameter smaller than the fine injection hole, which is difficult to process. Further, since the hole nozzle has poor atomization characteristics at a low fuel pressure and a small ejector effect at an injection hole, a high fuel pressure is required, and there is a concern that fuel consumption may be deteriorated due to a drive loss of the high fuel pressure pump. The present invention has been made in view of such conventional problems, and uses a swirl nozzle having a single injection hole to generate fine particles at a low fuel pressure by an air flow utilizing a squish flow and an ejector effect by a fuel flow. It is an object of the present invention to provide a fuel injection device for an internal combustion engine having excellent fuel injection characteristics and excellent fuel flow linearity, and to solve the above problems.

[0004]

According to the first aspect of the present invention, there is provided a fuel supply system for an internal combustion engine in which an injection hole of a fuel injection valve is made to directly face a cylinder and fuel is injected directly into the cylinder. In the injection device, a fuel guide that expands in diameter along the injection direction is provided on the downstream side of the injection hole of the fuel injection valve, and one end of an assist air passage is opened on the inner surface of the fuel guide, and the fuel guide faces the piston of the cylinder head. A squish portion is provided on the surface to be cut, and the other end of the assist air passage is opened in the squish portion. According to a second aspect of the present invention, in the fuel injection device for an internal combustion engine according to the first aspect, an annular recess is provided on an inner surface of the fuel guide, and one end of the assist air passage communicates with the annular recess. I do. According to a third aspect of the present invention, in the fuel injection device for an internal combustion engine according to the first or second aspect, the fuel injection valve includes a swirl element for imparting a swirl component to fuel, and the fuel injection valve is provided in the fuel guide. The turning direction of the assist air is the same as the turning direction of the fuel by the turning element. According to a fourth aspect of the present invention, in the fuel injection device for an internal combustion engine according to any one of the first to third aspects, an annular air passage coaxial with the center of the injection hole is provided in a nozzle portion of the fuel injection valve, and the middle of the assist air passage is provided. , And is communicated with the annular air passage. According to a fifth aspect of the present invention, in the fuel injection device for an internal combustion engine according to any one of the first to fourth aspects, the diameter of the assist air passage is increased toward the other end opening to the squish portion. According to a sixth aspect of the present invention, in the fuel injection device for an internal combustion engine according to the first to fifth aspects, the assist air passage opening to the inner surface of the fuel guide is formed at the center of the injection hole so as to generate a flow accompanying the fuel injection flow. The opening is provided at a predetermined angle. According to a seventh aspect of the present invention, in the fuel injection device for an internal combustion engine according to the fourth aspect, the opening end of the assist air passage communicating from the squish portion to the annular air passage is set so as to be deviated from the center of the annular air passage. It is characterized by the following.

[0005]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is an explanatory view showing a fuel injection valve according to an embodiment, FIG. 2 is a view of the fuel injection valve according to the embodiment as viewed from an arrow A, and FIG. 3 is an explanatory view showing a fuel injection device of an internal combustion engine according to the embodiment. 4 is a view on arrow B of the fuel injection device for an internal combustion engine according to the embodiment. First, the configuration will be described. The fuel injection device for an internal combustion engine according to the present embodiment includes a swirl nozzle 1 that generates a swirl flow in fuel by a direct injection type in a cylinder, and a swirl nozzle 1 downstream of an injection hole 2 of the swirl nozzle 1. The fuel guide 3 has a sectional diameter increasing toward the downstream side, an annular recess 4 provided in the fuel guide 3, an assist air outlet 5 provided in the annular recess 4, and a swirl flow through the annular recess 4. An assist air passage 6 configured to generate air, an annular air passage 7 that supplies air to the assist air passage 6,
Squish air inlet 8 opened in squish section 10
, An assist air passage 9 connecting the annular air passage 7 and the squish air inlet 8, and a squish portion 10. FIG. 5 is an explanatory view of the assist air passage 9, and FIG.
It is S6-S6 sectional drawing of. As shown in the drawing, the assist air passage 9 is formed such that the opening area on the air introduction port 8 side is large and the opening area on the annular air passage 7 side is small.

Next, the operation will be described. When the needle valve lifts and the needle valve and the seat portion of the swirl nozzle 1 are separated, fuel flows out through the gap. At this time, the fuel that has passed through the fuel swirling element upstream of the seat passes through the injection hole 2 while swirling, and the fuel that has passed through the injection hole 2 flows along the fuel guide 3 by the swirling force. When the assist air passage outlet 5 is provided in the fuel guide 3, the air in the assist air passage 6 is sucked by the ejector effect of the fuel. By this assist air, mixing of the fuel and the air proceeds, and the fuel is atomized. Furthermore, since the assist air is supplied from around the entire circumference to the spray by turning the annular recess 4, the spray is uniformly atomized. Since the diameter of the annular recess 4 is discontinuously larger than that of the fuel guide 3, it becomes easier to introduce air due to the fuel separation effect. Further, by installing the introduction port of the assist air passage in the squish section 10, the rising tumble flow and squish flow can be utilized.
In addition to the atomization effect during fuel spraying, a strong squish flow near the top dead center flows into the swirl nozzle 1 after the spraying ends, so that the fuel remaining in the fuel guide 3 can be sent out to the center of the combustion chamber, It is possible to improve combustion and prevent the fuel from adhering to the swirl nozzle 1, which is effective in reducing HC.

Although the embodiments of the present invention have been described above, the specific configuration of the present invention is not limited to the embodiments, and there may be design changes within the scope of the present invention. This is also included in the present invention. For example, FIGS.
As shown in FIG. 3, the assist air passage 6a is linearly arranged so as to point toward the center of the swirl nozzle 1, and the fuel guide 3
It is good also as composition which does not provide an annular concave part in a.

[0008]

As described above, according to the present invention, the structure is such that the inlet for the assist air is provided in the squish portion and the outlet for the assist air is provided in the spray guide. The use of the tumble flow and squish flow inside the fuel tank and the ejector effect of the fuel have improved the atomization and provided a fuel injection device for an internal combustion engine with excellent fuel flow rate linearity, thereby reducing combustion and improving fuel efficiency. Improvements can be achieved.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing a fuel injection valve according to an embodiment of the present invention.

FIG. 2 is a view as viewed from an arrow A of the fuel injection valve according to the embodiment;

FIG. 3 is an explanatory diagram showing a fuel injection device for an internal combustion engine according to the embodiment.

FIG. 4 is a view on arrow B of the fuel injection device for an internal combustion engine according to the embodiment;

FIG. 5 is an explanatory diagram of an assist air passage.

FIG. 6 is a sectional view taken along line S6-S6 of FIG.

FIG. 7 is an explanatory diagram showing another embodiment.

FIG. 8 is an explanatory diagram showing another embodiment.

[Explanation of symbols]

 Reference Signs List 1 swirl nozzle 2 injection hole 3 fuel guide 4 annular recess 5 assist air outlet 6 assist air passage 7 annular air passage 8 squish air inlet 9 assist air passage 10 squish portion

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor: Kenmei Kubo F-term in Nissan Motor Co., Ltd. 2 Takaracho, Kanagawa-ku, Yokohama-shi, Kanagawa 3G066 AA02 AA03 AB02 AD12 BA03 BA17 BA26 BA32 CC14 CC37 CC43 CC46

Claims (7)

[Claims] 1. A fuel injection device for an internal combustion engine in which an injection hole of a fuel injection valve is directly made to face a cylinder and directly injects fuel into the cylinder. A fuel guide is provided along the fuel guide, and one end of the assist air passage is opened on the inner surface of the fuel guide, and a squish portion is provided on a surface of the cylinder head facing the piston. A fuel injection device for an internal combustion engine, wherein an end is opened. 2. The fuel injection device for an internal combustion engine according to claim 1, wherein an annular recess is provided on an inner surface of the fuel guide, and one end of the assist air passage communicates with the annular recess. 3. The fuel injection valve according to claim 1, further comprising a swirl element for imparting a swirl component to the fuel, wherein a swirling direction of the assist air generated in the fuel guide is made the same as a swirling direction of the fuel by the swirl element. 2. The method according to claim 1, wherein
3. A fuel injection device for an internal combustion engine according to claim 2. 4. The fuel injection valve according to claim 1, wherein an annular air passage coaxial with the center of the injection hole is provided in a nozzle portion of the fuel injection valve, and a midway of the assist air passage communicates with the annular air passage. 4. The fuel injection device for an internal combustion engine according to claim 3. 5. The fuel injection device for an internal combustion engine according to claim 1, wherein the diameter of the assist air passage increases toward the other end of the squish portion. 6. An assist air passage opening on an inner surface of the fuel guide, wherein the assist air passage opens at a predetermined angle with respect to a center of an injection hole so as to generate a flow accompanying a fuel injection flow. 6. The fuel injection device for an internal combustion engine according to any one of claims 5 to 5. 7. The fuel injection device for an internal combustion engine according to claim 4, wherein an opening end of an assist air passage communicating from the squish portion to the annular air passage is set so as to be deviated from a center of the annular air passage. .