JPH05231268A - Fuel injection nozzle and manufacture thereof - Google Patents

Abstract

PURPOSE:To reduce the generation of smoke by forming an injection nozzle in an oblong shape in cross section and in a shape wherein the peripheral edge part on the inlet side of an injection nozzle has a fuel reservoir in the shape of triangular cone. CONSTITUTION:A fuel reservoir 17 is formed in the peripheral edge part on the injection inlet side of an injection nozzle 22, and the fuel reservoir 17 is formed in a triangular conical shape 24 wherein the width of the upper stream side 28 of the flow of fuel is increased, width is decreased toward a nozzle tip 21, and depth is increased in a curve-form manner toward the peripheral edge part on the inlet side of the injection nozzle. This constitution minimizes resistance against the flow of fuel, performs excellent spray, promotes mixture with air, and reduces the generation of smoke.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel injection nozzle for injecting fuel into a combustion chamber through injection holes and a method for manufacturing the same.

[0002]

2. Description of the Related Art Conventionally, as a molding method for manufacturing a tip of an injection nozzle or the like using a ceramic material containing ceramic particles, an injection molding method or a wax core is used, and then a wax core is used. A method of elution by heating is known. Further, in order to reduce the resistance of the fuel flow to the inner surface side of the injection hole, R (radiu) is used.
s of curve) or tapering is generally known. Further, it has been reported that, in the suckless type nozzle, the wraparound of the fuel near the nozzle hole induces the turbulence of the spray.

Further, Japanese Patent Laid-Open No. 53-82907 discloses an air compression direct injection internal combustion engine. The air compression direct injection internal combustion engine uses an injection nozzle having one slit-shaped opening for fuel injection. The position of the opening of this injection nozzle is set so that the fuel jet spreads over its entire width almost simultaneously at the same time and spreads as a wide-area thin film, and the passing cross-sectional area of the slit-shaped opening is 1 in the mixture generation and combustion method. It corresponds to one single-hole nozzle.

Further, Japanese Utility Model Laid-Open No. 59-34072 discloses a fuel injection nozzle. In the fuel injection nozzle, the injection hole is formed to be vertically long and has different widths in the longitudinal direction, and in a state where the piston is raised to the top dead center,
The cross-sectional shape of the injection hole is formed such that the longer distance from the injection hole to the wall surface of the combustion chamber where the fuel is injected is wider and the shorter distance is narrower.

[0005]

However, in order to prevent the turbulence of the spray from being caused by the wraparound of the fuel in the vicinity of the injection hole as described above, the vicinity of the injection hole is made to have an appropriate shape. However, there is a problem in practical use because machining is extremely difficult, and even if it is processed by a laser or the like, the cost is high.

Further, after molding by slip casting, a molded body having a complicated shape such as a deformed injection hole of a fuel injection nozzle, in which a leasable core is included, is produced,
There is also known a method of sintering after the core is eluted by heating or the like. However, elution of the core by heating or the like to impart curvature to the inner surface of the injection hole may cause cracks due to contraction of the inking layer during molding and drying, or the shape accuracy of the injection hole is not reliable. There's a problem.

Therefore, an object of the present invention is to solve the above-mentioned problems. A triangular pyramid whose width becomes smaller toward the tip of the nozzle on the inner surface side of the nozzle tip in which the injection hole is formed, that is, at the peripheral edge of the injection hole inlet side. To provide a fuel injection nozzle that forms a regular fuel pool, suppresses the turbulence of the flow due to the wraparound of the fuel, smoothes the flow of the fuel, and prevents the turbulence of the spray, and a manufacturing method thereof.

[0008]

In order to achieve the above object, the present invention is configured as follows. That is,
The present invention relates to a fuel injection nozzle comprising a nozzle body having a hole through which a fuel flow path and a needle valve are inserted, and a nozzle tip which is integrally formed with the nozzle body and has a nozzle hole formed therein. There is a fuel reservoir formed at the peripheral edge of the injection hole inlet side, that is, the peripheral edge of the nozzle tip inner surface side, and the shape of the fuel reservoir is such that the width on the upstream side of the fuel flow is large and the width is small toward the tip of the nozzle and The present invention relates to a fuel injection nozzle, which is formed into a triangular pyramid shape that is rounded and deeper toward the peripheral portion on the hole inlet side.

Further, in this fuel injection nozzle, the injection hole has a rectangular cross section.

In this fuel injection nozzle, at least the peripheral portion of the injection hole is made of zirconia ceramics.

Alternatively, according to the present invention, a step of adding water and a binder to the ceramic powder and mixing them to form a slurry,
Porous mold, that is, a casting mold that is a combination of a plaster mold and a mold, has a nozzle hole forming pin having a rectangular cross section, and a triangular pyramid shape attached to the tip of the nozzle hole forming pin at the tip of the nozzle hole inlet side. A step of arranging a silicon rubber member having a corresponding shape; a step of injecting the slurry into the cavity to solidify it by absorbing water; and a step of producing a molded body; extracting the injection hole forming pin from the casting mold; A step of demolding and drying, and a step of degreasing and firing the molded body to heat and remove the silicon rubber member to produce a fired body in which the shape of the silicon rubber member is transferred. It relates to a manufacturing method.

[0012]

The fuel injection nozzle and the method for manufacturing the same according to the present invention are configured as described above and operate as follows. That is, according to the present invention, a fuel pool is formed in the peripheral portion of the injection hole on the injection hole inlet side, and the fuel pool has a large width on the upstream side of the fuel flow, a small width toward the tip of the nozzle, and a small width on the edge of the injection hole. Formed in the shape of a triangular pyramid that is rounded and deeper toward the end, the resistance to the flow of fuel is minimized, the fuel flows smoothly, the penetration is increased, the atomization is good, and the mixing with air is promoted. The occurrence of smoke is reduced.

According to the present invention, in the manufacturing process, a silicon rubber member having a triangular pyramid shape corresponding to the shape of the injection hole inlet side peripheral edge portion is attached to the tip of the injection hole forming pin, and the injection hole inlet side peripheral edge portion is attached. Since a triangular pyramid shaped fuel reservoir was molded into
The shape of the silicon rubber member having a very small curvature can be transferred with high accuracy, and a desired shape of the injection hole inlet side peripheral portion can be formed with high accuracy.

[0014]

Embodiments of the fuel injection nozzle and the method for manufacturing the same according to the present invention will be described below with reference to the drawings. Figure 1
FIG. 3 is a sectional view showing a main part of an embodiment of a fuel injection nozzle according to the present invention. FIG. 2 is a plan view as seen from the direction of reference numeral A in FIG.

The fuel injection nozzle according to the present invention is for injecting fuel into a combustion chamber, and has a nozzle body 31 having a hole for inserting a fuel flow path and a needle valve, and the nozzle body 3.
1 and the nozzle tip 22, which is an integral structure and has a nozzle hole 23 formed therein. In this fuel injection nozzle, the nozzle body 31 is made of an SCM material or the like, and the nozzle body 31 and the nozzle tip 22 are joined at a joining portion 29. The nozzle tip 22 can be formed as a multi-injection hole composed of a plurality of injection holes 23. However, in this embodiment, in order to make the description easy to understand,
Only one injection hole 23 is shown.

The nozzle tip 22 is made of ceramics such as zirconia ZrO _{2 having} high heat resistance and high temperature. The outer surface 26 side of the nozzle tip 22 is a surface exposed to the combustion chamber. As shown in FIG. 2, the injection hole 23 formed in the nozzle tip 22 of the fuel injection nozzle is composed of a straight portion 33 having a rectangular cross section. Further, a fuel pool 17 is formed at the peripheral edge of the injection hole 23 on the injection hole inlet side, in other words, on the peripheral surface of the inner surface 25 side of the nozzle tip 22 on the injection hole inlet side. The shape of the fuel pool 17 is such that the width of the fuel flow upstream side 28 is large and the nozzle tip 21
The width of the triangular pyramid 24 is gradually reduced toward the edge of the nozzle hole, and is further rounded into a rounded R shape toward the periphery of the injection hole. Specifically, the shape of the fuel pool 17 is the injection hole 23.
R is a truncated triangular pyramid in which the part of is the central part
It is formed into a shape.

With this fuel injection nozzle, when the fuel supplied from the fuel injection pump is injected through the injection hole 23 by opening the needle valve, the resistance to the flow of fuel is minimized and the pressure loss of fuel pressure is reduced. The flow of fuel can be made smooth, the turbulence of the spray can be eliminated, the penetration of fuel can be increased, the mixing with air can be improved, a good combustion state can be ensured, and the occurrence of smoke can be reduced.

Next, an embodiment of the method of manufacturing the fuel injection nozzle according to the present invention will be described with reference to FIGS.
FIG. 3 is an explanatory view showing a process of disposing the injection hole forming pin and the silicon rubber member in the cavity of the ceramic molding apparatus, and FIG.
Is an explanatory view showing a step of injecting the slurry into the cavity, FIG. 5 is an explanatory view showing a step of extracting the injection hole forming pin and the forming pin from the cavity, and FIG. 6 is an explanatory view showing a step of drying and solidifying the inking portion. 7 and 8 are sectional views showing an example of a ceramics forming apparatus for achieving the method for manufacturing a fuel injection nozzle according to the present invention.

As shown in FIG. 7, the ceramics forming apparatus is preferably applied to manufacture a nozzle tip of a fuel injection nozzle used in a diesel engine, for example. In this ceramic molding apparatus, a mold 1 is provided with a slurry injection port, that is, a slurry injection passage 2 and a cavity 3 communicating with the slurry injection passage 2, and a metal hole having a polygonal shape at the tip. A through hole 4 and a pin insertion hole 18 for detachably attaching the pin insertion / removal rotary jig 6 having the injection hole forming pin 5 which is a forming pin are formed. The cavity 3 is formed on the lower surface of the mold 1, and the slurry injection passage 2 leads from the upper part of the mold 1 to the cavity 3. The shape of the cavity 3 is the outer shape of the tip of the fuel injection nozzle, that is, the nozzle tip 22. The shape of the injection hole forming pin 5 is formed so as to correspond to the shape of the injection hole 23 formed in the nozzle tip 22, and is formed in a rectangular shape here.

The mold 1 is set on the positioning table 8.
The upper surface 11 of the positioning table 8 is arranged in contact with the lower surface 12 of the mold 1. A hole 13 is formed in the positioning base 8, and a through hole 15 for moving up and down an inner surface forming pin 14 serving as a molding pin and a pin elevating jig 10 to which the inner surface forming pin 14 is attached is formed. ing. The pin raising / lowering jig 10 is provided with an appropriate fixing means such as a screw and the like.
It is detachably fixed to the inner surface forming pin 14 so that the inner surface forming pin 14 can be projected into the cavity 3.

A porous mold 9 made of a plaster mold or the like is arranged in the hole 13 formed in the positioning table 8. The porous mold 9 cooperates with the mold 1 and the inner surface forming pin 14 to form the cavity 3. In other words, the molding or casting mold is
A part of the wall surface of the cavity 3 is formed by the porous portion 30 and the remaining part is formed by the mold 1. The porous portion 30 of the porous mold 9 has a function of absorbing water from the slurry S injected into the cavity 3 from the slurry injecting passage 2 to cause the wall surface of the cavity to be inked and solidify the inlaid portion 7. ing.
A through hole 16 is formed in the porous mold 9 at a position facing the cavity 3, and the inner surface forming pin 14 can be moved up and down through the through hole 16. The inner surface forming pin 14 is set in a state in which it can rise in the through hole 16 and project into the cavity 3.

The ceramic molding apparatus is constructed as described above, and the molding apparatus can be used to mold the nozzle tip 22 in the fuel injection nozzle according to the present invention. That is, the nozzle tip 22 is manufactured by slip casting, which is one of the ceramic molding methods. A cavity 3 having a partially water-absorbing porous portion 30 is formed, and a slurry injection passage 2 communicating with the cavity 3 and a pin insertion hole 18 into which the injection hole forming pin 5 as a hole forming pin can be inserted are formed. This is one of the ceramic component molding methods for molding a ceramic material into a predetermined shape using a metal mold 1.

First, water and a binder are added to a ceramic powder of zirconia ZrO ₂ and thoroughly mixed by a ball mill to prepare a slurry S. On the other hand, in order to form the fuel reservoir 17 in the nozzle tip 22, the shape corresponding to the shape of the peripheral portion on the inner surface side of the injection hole, that is, the width of the fuel flow upstream side 28 is large and the width toward the nozzle tip 21 is made of silicon rubber. Is gradually reduced, and is rounded toward the injection hole edge.
A silicon rubber member 20 having a triangular pyramid shape 24 that becomes deeper in a shape is formed. Further, the injection hole forming pin 5 has a rectangular cross-sectional shape and a size of 0.1 after the injection hole 23 is fired.
It was formed to have a size of 5 × 0.35 mm. Then, FIG.
As shown in FIG. 1, the silicon rubber member 20 is attached to the inner surface forming pin 1
4, the injection hole forming pin 5 is inserted into the pin insertion hole 18, and the silicon rubber member 20 is attached to the tip 19 of the injection hole forming pin 5. .. At this time, the injection hole forming pin 5 was set in the cavity 3 so that the injection hole 23 had a long side formed from the upstream side 28 of the fuel flow toward the nozzle tip 21.

Then, as shown in FIG.
With the injection hole forming pin 5 and the silicon rubber member 20 having the triangular pyramid shape 24 arranged therein, the slurry S is injected into the cavity 3 through the slurry injection passage 2. When the slurry S is injected into the cavity 3, the slurry S infiltrates into the cavity 3 excluding the silicon rubber member 20 and the injection hole forming pin 5 while maintaining the shape of the silicon rubber member 20, and there, The water content of the slurry S is absorbed by the porous portion 30 of the porous mold 9, and the slurry S contains the wall surface 2 of the cavity 3.
7 is solidified and solidified to form a thickened portion 7. This meat part 7
Is not present in the portion where the silicon rubber member 20 and the injection hole forming pin 5 are present.
R, that is, the curved peripheral surface and the shape of the straight peripheral surface, that is, the straight portion 33 having a rectangular sectional shape of the injection hole forming pin 5, are transferred.

Therefore, in the state where the shape retaining property is developed in the inlaid portion 7, as shown in FIG. 5, the injection hole forming pin 5 is extracted from the inlaid portion 7 and the injected portion 7 has a straight injection hole. 23 is formed. Further, the forming pin 14 is pulled out from the inlaid portion 7, but at this time, the silicon rubber member 20 is in a state of being attached to the inlaid portion 7. With the solidified state of the inking part 7 further advanced,
As shown in FIG. 6, the inlaid portion 7 is taken out from the mold 1 and the porous die 9, and the inlaid portion 7 is sufficiently dried and degreased. The dried inlaid portion 7 was put into a firing furnace and heated to heat and remove, or burn, the silicon rubber member 20, and the inlaid portion 7 was fired to obtain a fired body. This fired body constitutes the nozzle tip 22 shown in FIG.

The nozzle tip 22 has a joint portion 2 on its end face.
The fuel injection nozzle can be completed by joining 9 to the nozzle body 31 made of SCM material using a solder material. The fuel spray nozzle was used to observe the fuel spray. As a comparative example, a nozzle tip having a perfect circular cross-sectional shape of the injection hole and having no fuel reservoir was prepared and compared with that of the present invention. Low engine speed range (1000 rp
In m), the conventional fuel injection nozzle showed a smoke generation of BOSCH 5, while the fuel injection nozzle according to the present invention has a smoke generation of BOSCH 3.7, which reduces the smoke generation by about 26%. Was confirmed.

[0027]

The fuel injection nozzle and the method for manufacturing the same according to the present invention are configured as described above and have the following effects. That is, according to the present invention, a fuel pool is formed in the peripheral portion of the nozzle hole formed on the nozzle tip on the injection hole inlet side, and the shape of the fuel pool is such that the width on the upstream side of the fuel flow is large and the width toward the nozzle tip is small. In addition, since it is formed in a triangular pyramid shape that is deep and rounded toward the periphery of the injection hole, the fuel flowing into the injection hole when the needle valve is opened is suppressed from turbulence due to its wraparound, and the resistance to the fuel flow is minimized. And smoothly flowed into the injection hole through the fuel flow path,
Increase penetration, promote mixing with air,
Combustion is performed well and smoke generation can be reduced.

Further, since the cross-sectional shape of the injection hole is rectangular, the fuel injected from the injection hole is further increased in penetration, and mixing with air is promoted.

Furthermore, since at least the peripheral portion of the injection hole is made of ceramics, the injection hole can be formed into a desired shape by forming the injection hole with a degree of freedom. Further, ceramics have high heat resistance, and can sufficiently maintain durability and strength even when exposed to high temperatures in the combustion chamber.

Further, the manufacturing method of this fuel injection nozzle is as follows:
In a cavity of a porous mold, that is, a casting mold in which a plaster mold and a mold are combined, a shape corresponding to the shape of the injection hole forming pin and the peripheral portion of the injection hole inlet side attached to the tip of the injection hole forming pin is provided. A silicon rubber member having the above is arranged, and a slurry is injected into the cavity to be solidified by absorbing water to produce a molded body, and the injection hole forming pin is pulled out from a casting mold, and the molded body is demolded and dried to form a molded body. Since the silicon rubber is degreased and fired and the silicon rubber is removed by heating, the shape of the silicon rubber can be easily transferred to the fired body. That is, a complicated minimal shape can be formed with high precision by molding ceramics, and the corner of the cross-sectional shape of the injection hole can be formed into a sharp shape. Therefore, it is possible to easily form a fuel reservoir in the peripheral portion of the nozzle tip on the inlet side of the nozzle hole, and to easily form a rectangular nozzle hole in communication with the fuel reservoir. When fuel is injected into the combustion chamber, the penetration is performed depending on its shape. Can be increased, the pressure loss of fuel pressure can be reduced, the air entrainment or air entrainment in the combustion chamber can be improved, and mixing with air can be promoted.

[Brief description of drawings]

FIG. 1 is a sectional view showing a main part of an embodiment of a fuel injection nozzle according to the present invention.

FIG. 2 is a plan view seen from the direction of reference numeral A in FIG.

FIG. 3 is an explanatory view showing a step of disposing the injection hole forming pin and the silicon rubber member in the ceramic molding apparatus in the method of manufacturing the fuel injection nozzle.

FIG. 4 is an explanatory view showing a step of injecting a slurry into a cavity in the method for manufacturing a fuel injection nozzle.

FIG. 5 is an explanatory view showing a step of extracting the injection hole forming pin and the forming pin from the cavity in the method for manufacturing the fuel injection nozzle.

FIG. 6 is an explanatory view showing a step of drying and solidifying the inlaid portion in the method for manufacturing a fuel injection nozzle.

FIG. 7 is a cross-sectional view showing an example of a ceramic molding apparatus for achieving the method for manufacturing a fuel injection nozzle according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Mold 2 Slurry injection passageway 3 Cavity 5 Injection hole forming pin 7 Inking part 9 Porous type (gypsum type) 14 Inner surface forming pin 17 Fuel pool 20 Silicon rubber member 21 Nozzle tip 22 Nozzle tip 23 Nozzle hole 24 Triangle Conical shape 28 Fuel flow upstream side 29 Joint part 31 Nozzle body 33 Straight part

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Keio Sekiyama 8 Tsutana, Fujisawa City Kanagawa Prefecture Isuzu Ceramics Research Institute Co., Ltd. (72) Inventor Masahiro Kyuoka 8th Tsutanaka Fujisawa City Kanagawa Prefecture Isuzu Co., Ltd. Ceramics laboratory

Claims (4)

[Claims] 1. A fuel injection nozzle comprising a nozzle body having a hole into which a fuel flow path and a needle valve are inserted, and a nozzle tip which is integrally formed with the nozzle body and has a nozzle hole formed therein. Has a fuel pool formed in the peripheral portion of the injection hole inlet side, and the shape of the fuel pool is such that the width on the upstream side of the fuel flow is large, the width is small toward the tip of the nozzle, and the width is toward the peripheral portion on the injection hole inlet side. A fuel injection nozzle characterized in that it is formed into a rounded and deep triangular pyramid shape. 2. The fuel injection nozzle according to claim 1, wherein the injection hole has a rectangular cross-sectional shape. 3. The fuel injection nozzle according to claim 1, wherein at least a peripheral portion of the injection hole is made of ceramics. 4. A step of forming a slurry by adding water and a binder to a ceramic powder to mix them, a casting mold cavity in which a porous mold and a mold are combined, and a nozzle for forming a nozzle hole having a rectangular cross section and the nozzle hole. A step of arranging a silicon rubber member having a shape corresponding to the triangular pyramid shape of the injection hole inlet side peripheral portion attached to the tip of the forming pin, injecting the slurry into the cavity to solidify by absorbing water to manufacture a molded body Step, step of extracting the injection hole forming pin from the casting mold, demolding and drying the molded body, and degreasing and burning the molded body to heat and remove the silicon rubber member, and the silicon rubber A method of manufacturing a fuel injection nozzle, comprising the step of manufacturing a fired body in which the shape of a member is transferred.