JPH06264845A - Fuel injection valve - Google Patents

Abstract

PURPOSE:To largely diffuse and atomize fuel grains in the perpendicular direction and atomize the fuel in a wide range by setting the tilt angle in the direction perpendicular to the flowing direction of air large within the tilt angle against the throttle nozzle center line on the circular tilt face of a needle valve tip section. CONSTITUTION:The nozzle hole 22 of the throttle nozzle 21 of a fuel injection valve 20 is formed into a complete round, and a needle valve 23 operated in the direction of the nozzle center line L3 is provided inside it. The needle valve 23 is operated in response to the fuel pressure applied to a center step section 231, and it is opened or closed while its circular seal face 232 is kept in contact with the circular inner wall face of a case. Multiple circular tilt faces 24x, 24y having different tilt angles alpha1, alpha2 against the nozzle center line L3 are formed on the outer periphery of a needle valve tip section 25. The tilt angle alpha2 in the perpendicular direction is set larger than the tilt angle alpha1 in the flowing direction X of air F within the tilt angles alpha1, alpha2 of the circular tilt faces 24x, 24y.

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 used for generating an air-fuel mixture in an engine, and in particular, a fuel injection is performed through an annular gap formed by a nozzle nozzle hole for spraying and a needle valve tip portion inside thereof. The present invention relates to a fuel injection valve equipped with a throttle nozzle.

[0002]

2. Description of the Related Art A fuel injection valve is provided at the tip of a fuel supply system of an engine, and fuel particles are sprayed into the air supplied to a combustion chamber by the fuel injection valve to generate an air-fuel mixture. Here, as the mixing of the fuel particles and the air is promoted, the air utilization rate of the air-fuel mixture advances earlier, and the combustion speed can be improved. Especially, in the compression ignition type diesel engine, mixing of fuel particles and air is promoted to improve the ignitability,
It is highly necessary to reduce the NOx generation rate and the smoke concentration.

A diesel engine with a swirl chamber has a higher compression ratio than a direct injection diesel engine.
It is often used because it can ignite relatively early by spraying fuel particles into the swirling air flow in the swirl chamber. For example, as shown in FIGS. 7 and 8, this engine with a swirl chamber is formed in the main chamber C in the cylinder block 1 and in the cylinder head 3, and has a swirl chamber centerline L2 perpendicular to the piston top surface. A swirl chamber 4 is provided, and the main chamber C and the swirl chamber 4 are communicated with each other through a nozzle 5 on the base 2 sandwiched between them.

In this engine, when the piston 6 sliding in the cylinder center line L1 direction in the cylinder block 1 is near the compression top dead center, the main chamber C is formed by the recess 7 on the top surface of the piston 6. . The swirl chamber 4 of this engine is formed continuously with a cylindrical wall surface 402 centering on the swirl chamber centerline L2, and on the upper side of the cylindrical wall surface 402, and at the same time, an upper opening 501.
The downward flow f2 toward the upper opening 501, which is formed continuously through a semi-spherical dome wall surface 401 that deflects the upward flow f1 from the above to the downward flow f2 and an annular inclined surface 404 below the cylindrical wall surface. Low wall surface 4 deflected to the flowing low wall flow f3
And 03. An injector mounting hole 8 is formed in the central portion of the dome wall surface 401 with a predetermined inclination with respect to the swirl chamber center line L2, and a throttle nozzle type fuel injection valve 9 is attached thereto.

A throttle nozzle type fuel injection valve 9 is shown in FIG.
As shown in FIG. 5, the holder 901 is fixed to the portion of the cylinder head 3 facing the swirl chamber, and the throttle nozzle 11 is held at the tip of the holder 901. The throttle nozzle 11 is provided inside the nozzle injection hole 12 with a needle valve 13 that operates in the direction of the nozzle center line L3 (see FIG. 9) of the throttle nozzle, and the needle valve 13 has a central step portion 13 thereof.
1 operates in the direction of the nozzle center line L3 in accordance with the level of the fuel pressure received by No. 1, and the annular sealing surface 132 of the case 111
It opens and closes by contacting and separating from the inner wall surface of. Needle valve 13 here
Is provided with a needle valve tip 15 having an annular inclined surface 14 that is inclined with respect to the nozzle center line L3 at its tip, and this needle valve 13 is a solid line from the valve closing position p1 shown by the two-dot chain line in FIG. When actuated to the valve opening position p2 shown, fuel injection can be performed through the annular gap t formed by the nozzle injection hole 12 and the needle valve tip portion 15.

In the engine equipped with such a fuel injection valve 9, air is pushed from the main chamber C on the top surface Pf of the piston into the swirl chamber 4 through the injection port 5 in the compression stroke to generate the swirling flow F, and the throttle nozzle. Spray fuel from 11. Then, the fuel spray flux is agitated with the air by the swirling flow F,
An air-fuel mixture is generated, and this air-fuel mixture ignites to start combustion expansion. The air-fuel mixture that has started this combustion expansion is ejected from the nozzle 5 at a predetermined nozzle angle β with respect to the piston top surface Pf, and the gas mixture injected into the main chamber C is the nozzle centerline L5 (see FIG. 8).
, The main combustion is performed by diffusion, and the engine performs a combustion expansion stroke.

[0007]

Here, FIG. 9 and FIG.
As shown in FIG.
The inclination angle α0 of the annular inclined surface 14 with respect to the nozzle center line L3 is constant over the entire circumference, and the spray angle (= 2 × α0) of a single spray flux sprayed through the annular gap t is constant over the entire circumference. Is. Therefore, the spray flux is swirling flow F
When diffused by the swirl flow F, the swirl flow is relatively diffused in the direction of the swirl flow F, but is orthogonal to the swirl flow F.
Not much diffused in the direction of.

As described above, when the fuel is sprayed into the swirl chamber 4 by the fuel injection valve 9 having the throttle nozzle 11, the diffusion of the fuel particles in the direction of the swirl center line L4 of the swirl chamber 4 is not sufficiently performed. Therefore, in this fuel injection valve, it was not possible to sufficiently disperse the fuel particles throughout the swirl chamber 4 to improve the ratio of contact between the air and the fuel particles, that is, the air utilization rate. As a result, the ignitability of the swirl chamber 4 using this fuel injection valve cannot be sufficiently improved, the combustion period tends to be prolonged, the smoke concentration of the engine cannot be reduced sufficiently, and the fuel consumption deteriorates. There was An object of the present invention is to provide a fuel injection valve capable of improving the air utilization rate at the time of mixing air for producing an air-fuel mixture and fuel particles.

[0009]

In order to achieve the above-mentioned object, the present invention is provided at a predetermined fuel spray position supported by a base portion of an engine and in which air for generating an air-fuel mixture of the engine flows. Equipped with a throttle nozzle
A needle valve tip portion is provided inside the nozzle injection hole of the throttle nozzle, the needle valve tip portion having an annular inclined surface that operates in the direction of the center line of the throttle nozzle and is inclined with respect to the throttle nozzle center line. In the fuel injection valve that injects fuel through the annular gap formed by the needle valve tip portion, the inclination angle of the annular inclined surface of the needle valve tip portion with respect to the throttle nozzle center line is the inclination angle in the air flow direction. Further, the inclination angle in the direction perpendicular to the flow direction of the air is set to be large.

[0010]

The angle of inclination of the annular inclined surface at the tip of the needle valve with respect to the center line of the throttle nozzle is more than that of the air flow direction.
Since the inclination angle in the direction perpendicular to the air flow direction is set large, the fuel particles can be diffused and sprayed more in the direction perpendicular to the air flow direction, and the flowing air and fuel particles at the fuel spray position Can promote mixing.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The fuel injection valve 20 of FIG. 1 is mounted in a swirl chamber 4 of an engine with a swirl chamber similar to that shown in FIG. In addition, the fuel injection valve 20 here is different from that shown in FIGS. 7 to 10 only in the configurations of the nozzle injection hole 22 (see FIG. 3) and the needle valve 23 in the throttle nozzle 21,
Here, the same reference numerals are given to the same portions, and duplicate description will be omitted. A throttle nozzle type fuel injection valve 20 is attached to the fuel injection valve mounting hole 8 of the swirl chamber 4 of FIG. The fuel injection valve 20 is composed of a retainer 201 fixed to a portion of the cylinder head 3 facing the swirl chamber, and a throttle nozzle 21 retained at the tip of the retainer 201. As shown in FIG. 3, the throttle nozzle 21 has a nozzle injection hole 22 formed in a perfect circle and has a needle valve 23 operating in the direction of the nozzle center line L3 inside thereof, and the needle valve 23 has a central step portion. 231 operates in the direction of the nozzle center line L3 in accordance with the level of fuel pressure received by 231 and its annular seal surface 23
2 is brought into contact with and separated from the annular inner wall surface of the case 211 to open and close.

The needle valve 23 is provided with a needle valve tip portion 25 at its tip portion, and the needle valve tip portion 25 has a ring-shaped inclined surface 2 having different inclination angles α1, α2 with respect to the nozzle center line L3 on the outer periphery thereof.
4x, 24y are formed. That is, as shown in FIG. 3, the annular inclined surface 24x in the X direction, which is the direction of the swirling flow F, has a relatively small inclination angle α1, and the annular inclined surface in the Y direction, which is a direction perpendicular to the direction of the swirling flow F. As shown in FIG. 4, 24y has a relatively small inclination angle α2. The nozzle injection hole 22 facing the needle valve tip 25 is a perfect circle. Therefore, when the fuel is injected through the annular gap t (see FIG. 5) formed between the nozzle injection hole 22 and the needle valve tip 25, the injection angle in the X direction is as shown in FIGS. 1 and 3. 2 × α1, the injection angle in the Y direction is 2 × α2 as shown in FIGS. 2 and 4, and the fuel particles are dispersed more in the Y direction than in the X direction, that is, in the direction orthogonal to the direction of the swirling flow F. Comes to be sprayed.

The casing 211 of the throttle nozzle 21 shown in FIGS. 3 and 4 is formed with a fuel passage 26 for guiding fuel to the central step portion 231 side of the needle valve 23, and a well-known high-pressure fuel supply system is connected to the passage. Has been done. 3 and 4, the pin 28 fixed to the side wall of the needle valve 23 and the casing 211 that guides the pin 28 only in the direction of the nozzle center line L3.
The long groove 29 of the inner wall is shown. Here, the pin 28 and the long groove 29
The rotation of the needle valve 23 around the nozzle center line L3 can be restricted by the action of. An engine equipped with such a fuel injection valve 9 (see FIG. 7) causes air to flow from the main chamber C into the swirl chamber 4 through the injection port 5 in the compression stroke, and the fuel injection valve 20 causes the fuel particles to flow into the swirl flow F. The mixture is sprayed to produce a mixture of fuel and air, and the mixture is ignited and then injected from the injection port 5 into the main chamber C.
To complete the main combustion.

At this time, the throttle nozzle 2 of the fuel injection valve
1 receives high-pressure fuel from a high-pressure fuel injection pump (not shown) at the central step 231 through the fuel passage 26, and when the fuel pressure level exceeds a predetermined valve opening pressure, the needle valve 23 is opened from the valve closing position P1. After switching to the valve position P2, fuel injection is performed through the annular gap t formed by the nozzle injection hole 22 and the needle valve tip 25. As for the distribution of the spray flux at this time, since the injection angle 2 × α2 in the Y direction is sufficiently large with respect to the injection angle 2 × α1 in the X direction, a sufficiently large injection is performed in the Y direction orthogonal to the direction of the swirling flow F. Even if the fuel particles are diffused at an angle of 2 × α2 and are sprayed at a relatively small injection angle of 2 × α1 in the X direction, the fuel particles in this direction are largely diffused in the X direction by the action of the swirling flow F. . As a result, according to this fuel injection valve, the fuel particles are diffused in the entire area of the combustion chamber 4 and sufficiently mixed with the air, so that the air utilization rate can be improved, and from this point, the ignitability is improved. Become.

In the engine of FIG. 1 using the fuel injection valve 20 as described above, early ignition is performed, combustion proceeds with the air in the main chamber C at an early stage, the combustion period is shortened, and the exhaust gas concentration of the engine is reduced. The result is improved fuel efficiency. Further, in FIG. 6 (a),
The fuel injection valve 30 as another embodiment of the present invention is shown.
The fuel injection valve 30 is mounted in the swirl chamber 4 of an engine with a swirl chamber similar to that shown in FIG. Moreover, the fuel injection valve 20 here is a needle in which the two nozzle injection holes 32 and the two needle valve tip portions 35 are integrally formed in the throttle nozzle 31, as compared with those shown in FIGS. The configuration is different only in that the valve 33 is provided, and redundant description will be omitted here.

The fuel injection valve 30 shown in FIG. 6A is a retainer 301 fixed to the portion of the cylinder head 3 facing the swirl chamber, and a throttle nozzle 3 retained at the tip of the retainer 301.
1 and. The throttle nozzle 31 has two nozzle injection holes 3 parallel to each other along the direction of the nozzle center line L3.
2 is formed (see FIG. 6B). Each nozzle nozzle 32
A needle valve tip portion 35 that operates in the direction of the nozzle center line L3 is provided inside each of the needle valves 33, and the needle valve 33 that integrally includes the two needle valve tip portions 35 has a fuel pressure level that the central step portion 331 receives. In the direction of the nozzle center line L3,
The two annular sealing surfaces 332 are brought into contact with and separated from the two annular inner wall surfaces of the casing 311 to open and close.

Here, the two needle valve tip portions 35 are formed around two tip center lines L3 'and L3' which are parallel to the nozzle center line L3. The needle valve tip portions 3 are formed with annular inclined surfaces 34x and 34y having different inclination angles α1 and α2 along the outer circumference thereof. That is, the inclination angle α1 of the annular inclined surface 24x in the X direction, which is the direction of the swirling flow F, is relatively small, and is outside in the Y direction that is a direction perpendicular to the direction of the swirling flow F. The angle of inclination α2 of the annular inclined surface 34y, which has the same shape as the annular inclined surface 24x on the opposite inner side, is formed to be relatively large.

When fuel is injected by such a fuel injection valve 30, the injection angle in the X direction is 2 × α1 as in FIG. 1, the injection angle in the Y direction is 2 × α2, and the spray width is 2 The distance e between the two nozzle center lines L3 is larger than that of the fuel injection valve 20 of FIG. Therefore, the fuel particles can be dispersed and sprayed to a greater extent in the Y direction than in the X direction, that is, in the direction perpendicular to the direction of the swirling flow F. As a result, this fuel injection valve is similar to the fuel injection valve of FIG. And the combustion chamber 4
The fuel particles can be diffused to a greater extent throughout the region, and the fuel particles and air can be sufficiently mixed to improve the air utilization rate.

[0019]

As described above, according to the present invention, of the inclination angles of the annular inclined surface of the needle valve tip portion with respect to the throttle nozzle center line, in particular, the inclination angle of the flow perpendicular direction perpendicular to the air flow direction. Is set to a large value, and the fuel particles can be sprayed more widely in the same direction, so the fuel particles can be sprayed over a wide range of the fuel spraying position, can be sufficiently mixed with air, and the air utilization rate can be improved. From this point, the ignitability of the engine equipped with this fuel injection valve can be improved.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view of a main part of an engine with a swirl chamber including a fuel injection valve according to the present invention.

FIG. 2 is a plan sectional view of a main part of a swirl chamber of the engine shown in FIG.

FIG. 3 is an enlarged main part sectional view of the fuel injection valve in FIG. 1.

FIG. 4 is a cross-sectional view of a main part of the fuel injection valve of FIG. 3 when viewed from the side.

5 is a front view of a nozzle injection hole of the fuel injection valve of FIG.

FIG. 6 (a) is an enlarged main part sectional view of a fuel injection valve as another embodiment of the present invention. (B) is a front view of a nozzle injection hole of the same fuel injection valve.

FIG. 7 is a schematic cross-sectional view of a main part of an engine including a conventional fuel injection valve.

8 is a plan sectional view of a main part of a swirl chamber of the engine shown in FIG.

9 is an enlarged main part sectional view of the fuel injection valve in FIG. 7. FIG.

10 is a plan view of a nozzle injection hole of the fuel injection valve in FIG. 7.

[Explanation of symbols]

 1 Cylinder Block 3 Cylinder Head 4 Vortex Chamber 5 Injection Port 6 Piston 20 Fuel Injection Valve 21 Throttle Nozzle 201 Cage 22 Nozzle Injection Hole 23 Needle Valve 24x Annular Slope 24y Annular Inclined Surface 25 Needle Valve Tip 32 Nozzle Injection Hole 33 Needle Valve 34x annular inclined surface 34y annular inclined surface 35 needle valve tip part α1 injection angle α2 injection angle F swirl flow Pf piston top surface C main chamber t annular gap

Claims (1)

[Claims] 1. A throttle nozzle, which is supported by a base portion of an engine and is arranged opposite to a predetermined fuel spray position where air for generating an air-fuel mixture of the engine flows, the inside of a nozzle injection hole of the throttle nozzle. A needle valve tip portion that operates in the direction of the center line of the throttle nozzle and has an annular inclined surface that is inclined with respect to the throttle nozzle center line, and is formed by the nozzle injection hole and the needle valve tip portion. In the fuel injection valve that injects fuel through the annular gap, the inclination angle of the annular inclined surface of the needle valve tip portion with respect to the throttle nozzle center line is more perpendicular to the air flow direction than the air flow direction inclination angle. A fuel injection valve characterized by having a large inclination angle in the direction.