JPH04347360A - Injection nozzle and manufacture thereof - Google Patents

Abstract

PURPOSE:To provide an injection nozzle with a small-sized, torsional nozzle hole and its manufacture. CONSTITUTION:An injection nozzle is provided with a torsional nozzle hole 17 being twisted over a specified angle toward an outlet 22 at the outside from an inlet 21 at the side of a nozzle sack and, whose sectional form is a rectangle, in its nozzle tip 20. This torsional nozzle hole 17 is formable in the floowing procedures that slurry is poured into a cavity of a die on which a torsional nozzle hole forming pin is set up, water content in the slurry is absorbed by a porous mold, forming a thick solid part, and then the torsional nozzle hole forming pin is extracted from this thick solid part as twisting it as far as the specified angle.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an injection nozzle having an injection hole made of a material such as ceramics containing ceramic particles, and a method for manufacturing the same.

0002

[Prior Art] Conventionally, as a molding method for manufacturing small precision parts such as the tip of an injection nozzle using a ceramic material containing ceramic particles, injection molding or slip casting using a wax core has been used. , a method of heating and eluting a wax core, etc. are known.

[0003] Furthermore, as a mud casting method for silicon nitride ceramics, there is a method disclosed in JP-A-64-5977. This molding method involves adding ammonium salt of polyacrylic acid as a deflocculant to silicon nitride ceramic slurry by 0.1 to 0.7 to the slurry powder.
% by weight and an acrylic emulsion as a binder was added to the slurry and cast.

[0004] In addition, as an injection nozzle having a nozzle tip made of ceramics, Japanese Utility Model Application No. 57-122778
There is something disclosed in the publication No. In the injection nozzle, each injection hole formed in the nozzle chip is made of a ceramic member, and the ceramic member is shrink-fitted to the valve seat portion of the nozzle body.

[0005] Furthermore, when forming an irregularly shaped injection hole at the tip of the injection nozzle, machining, laser processing,
It is generally formed by electrical discharge machining.

[0006]

[Problems to be Solved by the Invention] However, in the above-mentioned conventional injection molding method, the composition is filled into the mold under high pressure. ) etc. may be damaged when pressurized.

[0007] Furthermore, the method of heating and eluting the wax core after molding by slip casting has problems with accuracy, making it impossible to form holes with high precision, and shrinkage of the inked part during molding drying. Cracks may occur. Further, the molding method disclosed in the above-mentioned Japanese Patent Application Laid-open No. 64-5977 also has similar problems.

Therefore, in order to solve the above problem, the present applicant has developed a method for molding a ceramic member, a molding device for a ceramic member, and an injection nozzle manufactured by the molding method.
It was previously filed as Japanese Patent Application No. 2-415086. However, although the method for molding a ceramic member according to the present invention can form an irregularly shaped nozzle hole, there is no disclosure of a nozzle hole having a spirally twisted shape and a method for forming a twisted nozzle hole. It is.

[0009] Furthermore, when forming an irregularly shaped injection hole at the tip of the injection nozzle, machining, laser processing,
Although it can be formed by electric discharge machining, it has been impossible to machine the nozzle hole into a twisted shape, or to perform laser machining or electric discharge machining.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to solve the above-mentioned problems, and it is possible to form a nozzle hole having a polygonal shape or the like and twisted in the flow direction with high precision using a ceramic material. An object of the present invention is to provide an injection nozzle capable of improving air entrainment by imparting a swirling flow to fuel injected from the injection hole, and a method for manufacturing the same.

[0011]

[Means for Solving the Problems] In order to achieve the above object, the present invention is constructed as follows. That is,
The present invention relates to an injection nozzle characterized by having an injection hole twisted in the flow direction.

[0012] In this injection nozzle, the cross-sectional shape of the injection hole is rectangular or elliptical.

[0013] In this injection nozzle, the surrounding portion forming the injection hole is made of ceramics.

Alternatively, the present invention includes a step of injecting slurry into a cavity of a mold in which a pin for forming twisted injection holes is arranged, a step of absorbing water in the slurry into a porous mold to form a solidified part, a step of pulling out the twisted injection hole forming pin from the solidified part while twisting it at a predetermined angle to produce a chip molded body; a step of firing the dry and solidified chip molded body to create a chip sintered body; The present invention relates to a method of manufacturing an injection nozzle, which comprises a step of joining the chip sintered body to a nozzle body.

[0015]

[Operation] The injection nozzle and the method for manufacturing the same according to the present invention are constructed as described above, and operate as follows. That is, since this injection nozzle has a nozzle hole that is twisted in the flow direction, it is possible to impart a swirling flow to the fuel injected from the nozzle hole, thereby improving air entrainment.

[0016] Furthermore, the method for manufacturing this injection nozzle includes injecting slurry into a cavity of a mold in which a pin for forming twisted injection holes is arranged, and causing water in the slurry to be absorbed into a porous mold to form a solidified part. Then, the torsion injection hole forming pin was pulled out from the solidified part by twisting it at a predetermined angle to produce a chip molded body, so that the water in the slurry was absorbed by the porous mold and the shape was retained in the solidified part. By twisting and pulling out the torsion nozzle forming pin, which is set to be removably attached to the mold in the solidified state where the properties have been expressed, a torsion-shaped nozzle is formed. is in a state where almost no shrinkage has occurred, so the pin for forming the torsional nozzle hole can be removed while maintaining the predetermined shape of the hole to be formed in the solidified part, and the shape of the torsional nozzle hole is not destroyed. does not occur.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of an injection nozzle and a method of manufacturing the same according to the present invention will be described with reference to the drawings. First, an injection nozzle according to the present invention will be explained with reference to FIGS. 1 and 2. FIG. 1 is a schematic cross-sectional view showing an embodiment of the shape of the injection hole formed in the nozzle tip of the injection nozzle according to the present invention;
FIG. 2 is an enlarged view of the injection nozzle in FIG. 1 as seen from the injection hole direction, that is, arrow A, and FIG. 3 is a perspective view of the nozzle tip in FIG. 1.

The injection nozzle according to the present invention is shown in FIGS. 1 and 2.
Or, as shown in Fig. 3, the nozzle hole 1 has a twisted shape in the flow direction.
7 has a plurality of nozzle holes formed in the nozzle chip 20. The end surface 23 of the nozzle tip 20 is joined to the nozzle body to form an injection nozzle, and a nozzle sack 19 is formed inside the nozzle tip 20. These twisted nozzle holes 17 are formed in a rectangular, polygonal, or elliptical cross-sectional shape, and are twisted over a predetermined angle from an inlet 21 opening into the nozzle sack 19 to an outlet 22 opening to the outside. formed into a shape. Further, the nozzle tip 20 is made of high-temperature, high-strength ceramics such as silicon nitride (Si3 N4) and silicon carbide (SiC), which are highly heat resistant. Twisted injection hole 1 of this injection nozzle
As an example of 7, the cross-sectional shape of the twisted nozzle hole 17 is 0.2 m.
It is formed into a rectangle of m x 0.6 mm, with an inlet 21 opening toward the nozzle sack 19 and an outlet 22 opening outwards being twisted at an angle of 45 degrees relative to each other.

Therefore, in this injection nozzle, the fuel pressure from the fuel supply means such as the fuel injection pump is applied to the needle valve of the injection nozzle, the fuel passage is opened, and the fuel is discharged from the fuel reservoir of the injection nozzle, that is, the injection chamber. It flows into the nozzle sack 19 and is injected from the nozzle sack 19 to the outside through the twisted injection hole 17. The injected fuel injected from the twisted nozzle hole 17 obtains a swirling vector by passing through the twisted nozzle hole passage, and is injected as a circular swirling flow. Therefore, the swirling flow entrains surrounding air, improving air entrainment. In the injection nozzle according to the present invention, the twisted injection hole 17 is formed in a rectangular cross-sectional shape of 0.2 mm x 0.6 mm and twisted at an angle of 45 degrees as described above, and has the twisted injection hole 17. A comparison of the injection performance between the injection nozzle and the injection nozzle having a straight rectangular injection hole without twisting revealed that the injection nozzle with the twisted injection hole 17 had a higher air flow rate than the injection nozzle with an untwisted injection hole. We were able to improve entrainment by approximately 5%.

Next, a method of manufacturing an injection nozzle according to the present invention will be explained with reference to FIGS. 4 and 5. FIG. 4 is a cross-sectional view showing a ceramic member molding apparatus for manufacturing an injection nozzle according to the present invention, and FIG. 5 is an enlarged cross-sectional view of a main part of the molding apparatus shown in FIG. 4. This ceramic member forming apparatus is applied, for example, to manufacturing a nozzle tip for a fuel injection nozzle used in a diesel engine. In this molding apparatus, a slurry injection port 2 is provided in a mold 1.
A cavity 3 communicating with the slurry injection port 2 is formed therein, and a rotating jig 6 for inserting and removing a pin is removably provided with a metal twisted nozzle hole forming pin 5 having a polygonal or other twisted shape at the tip. A through hole 4 for attachment is formed. The cavity 3 is formed on the lower surface of the mold 1, and the slurry inlet 2 communicates with the cavity 3 from the upper surface of the mold 1. The shape of the cavity 3 has the outer shape of the tip of the fuel injection nozzle.

The mold 1 is set on a positioning table 8. The upper surface 11 of the positioning table 8 is placed in contact with the lower surface 12 of the mold 1. A hole 13 is formed in the positioning base 8, and a core 14 that becomes a molding pin and the core 1 are formed in the positioning base 8.
A through hole 15 is formed for raising and lowering the core lifting jig 10 to which the core lifting jig 4 is attached. The core lifting/lowering jig 10 is removably fixed to the positioning table 8 with suitable fixing means such as screws,
It functions as a molding pin for the nozzle sack 19 that can protrude into the cavity 3.

A porous mold 9 made of gypsum or the like is placed in the hole 13 formed in the positioning table 8. This porous type 9
has the function of absorbing moisture from the slurry S injected into the cavity 3 from the slurry inlet 2 and solidifying the slurry inlay portion 7 . A through hole 16 is formed in the porous mold 9 at a position facing the cavity 3, and the core 14 is configured to be able to move up and down through the through hole 16. The core 14 is set in such a state that it can rise through the through hole 16 and protrude into the cavity 3 formed in the mold 1 . In some cases, a concave portion 18 may be formed on the outer surface of the core 14, and the tip of the torsional nozzle hole forming pin 5 may be fitted into the concave portion 18. Alternatively, the tip end surface of the torsion nozzle hole forming pin 5 may be formed into a shape corresponding to the outer shape of the core 14. Alternatively, apply Vaseline or the like to the surface of the core 14, set the torsion nozzle forming pin 5 in contact with the core 14 with no gap, and pour the slurry S into the cavity 3 from the slurry inlet 2. By injecting, the molding hole can be formed accurately and with high precision. This core 14
is set to protrude into the cavity 3, thereby forming, for example, a nozzle sack 19 of a fuel injection nozzle.

This apparatus for molding a ceramic member is constructed as described above, and the injection nozzle according to the present invention, which is a ceramic member, can be manufactured using the apparatus in the following manner. That is, in this embodiment, the injection nozzle is manufactured by slip casting, which is one of the ceramic molding methods. That is, the manufacturing method of this injection nozzle includes a step of injecting slurry S into a cavity 3 from a slurry injection port 2 formed in the upper part of a mold 1 in which a twisted injection hole forming pin 5 is disposed, and a step of injecting the slurry S into a cavity 3. In the process of making the mold 9 absorb water, the pin 5 for forming the torsion nozzle hole 5 is pulled out from the solidified part 7 when the solidified part 7 exhibits shape retention, and the torsion nozzle hole 17 is formed in the solidified part 7. This process further includes a step of causing the porous mold 9 to absorb moisture in the slurry S to further solidify the solidified portion 7. The slurry S injected into the cavity 3 has moisture absorbed by the porous mold 9 and forms a solidified layer 7 on the porous mold 9 and the core 14.
It forms the

In this injection nozzle manufacturing method, the inked layer, that is, the inked solidified portion 7, has a suitable amount of moisture absorbed from the inked layer and an appropriate amount of moisture remains in the inked layer. , no shrinkage occurred in the solidified part 7. Then, when the solidified part 7 exhibits shape retention but no contraction occurs in the solidified part 7, the torsion nozzle forming pin 5 is moved from the solidified part 7 to a predetermined position. By pulling out while twisting over an angle, a highly accurate and strong twisted nozzle hole 17 can be formed in the solidified part 7. Further, the core 14, which is a forming pin that forms the nozzle sack 19, is lowered from the positioning table 8 and extracted from the hardened ink portion 7. Next, the torsion injection hole forming pin 5 and the core 14 are attached to the hardening part 7.
After removing it from the mold, the fleshed part 7 is further molded with a porous mold 9.
At this time, shrinkage occurs in the solidified part 7, but since the torsion injection hole forming pin 5 has already been removed from the solidified part 7, the solidified part 7 is not destroyed and a molded body of ceramic material is formed. Further, the mold 1 is removed from the positioning table 8, and the molded body composed of the solidified portion 7 is removed from the mold. This molded body becomes a sintered body by main firing, and the nozzle tip 20 of the fuel injection nozzle is manufactured. An injection nozzle can be manufactured by joining this nozzle tip 20 to a nozzle body.

In this injection nozzle manufacturing method, a molded body as shown in FIG. 4, for example, can be manufactured by sequentially injecting into the cavity 3 a plurality of types of slurry S having different components and constituent concentrations. That is, it is possible to mold the molded body into a molded body having different compositions depending on the purpose in the height direction, and by firing the molded body, it is possible to produce a sintered body made of different ceramic materials. Next, when manufacturing an injection nozzle using this molded body,
Regarding the nozzle tip 20 of the injection nozzle, the portion near the joint surface with the nozzle body, the portion adjacent to the joint surface portion, and the tip portion adjacent to the portion and in which the twisted nozzle hole 17 is formed are made of a ceramic material. It is also possible to configure the types and composition ratios of the components to be different from each other. For example, the tip part is made of a heat-resistant and high-strength ceramic material, and the part near the joint surface with the metal nozzle body is made of Al2.
It can be manufactured from a ceramic material with a rich composition of O3 and Y2 O3, and the metal contained in the ceramic and the metal contained in the nozzle body can form a metal-to-metal joint, and the tip part and the metal nozzle body can The bond can be strengthened.

Next, a specific example of the method for manufacturing this injection nozzle will be explained. First, silicon nitride (Si3 N4
) ceramic powder, sintering aid, peptizer, water, and polyvinyl alcohol as an organic binder were blended in a predetermined amount. Next, slurry S was obtained by mixing in a ball mill. The slurry S thus obtained was poured into the cavity 3 through a slurry injection port 2 formed in a nozzle chip manufacturing mold, that is, a metal mold 1, of a nozzle chip in an injection nozzle shown in FIGS. 4 and 5. The slurry S injected into the cavity 3 has water absorbed by the porous mold 9, and the slurry S is poured into the cavity 3.
After a predetermined period of time, when the ink layer develops shape retention, the pin 5 for torsion injection hole forming attached to the mold 1 is solidified. At the same time, the core 14, which is a forming pin attached to the positioning table 8, is extracted from the solidified part 7 while being twisted at a predetermined angle (for example, 45°). In this state, the solidified part 7 is left in the mold, and the porous mold 9 further absorbs and discharges water from the solidified part 7, thereby solidifying the part 7. After the solidified portion 7 was solidified to form a molded body of the ceramic member, the molded body was removed from the mold to obtain a nozzle tip molded body having a twisted nozzle hole 17. A nozzle chip sintered body can be obtained by firing this nozzle chip molded body, and this nozzle chip sintered body is the ceramic nozzle chip 20. This nozzle tip 20
In some cases, the injection nozzle can be completed by processing and joining it to the nozzle body.

[0027] In this method of molding a ceramic member,
In addition to silicon nitride, aluminum titanate, mullite, zirconia, potassium titanate, and the like can be used as the ceramic powder. Further, as the organic binder, in addition to polyvinyl alcohol, a thermoplastic acrylic resin that can suppress dimensional shrinkage in the manufacturing process of the ceramic member can be used.

[0028]

Effects of the Invention The injection nozzle and method for manufacturing the same according to the present invention are constructed as described above, and have the following effects. That is, in the injection nozzle according to the present invention, the shape of the nozzle hole formed in the nozzle tip is twisted in the flow direction, so that when fuel is injected through the twisted nozzle hole, the fuel is not in a sloppy state. It is injected in a swirling manner to improve air entrainment. In this case, if the cross-sectional shape of the twisted nozzle hole is formed into a square such as a rectangle, the area where the injected fuel comes into contact with the air increases, which is preferable from the viewpoint of air entrainment. Further, a surrounding portion forming the twisted nozzle hole,
For example, when the nozzle tip is made of ceramics, the twisted nozzle hole can be formed extremely easily and with high precision.

[0029] Furthermore, in the method for manufacturing an injection nozzle according to the present invention, a slurry is injected into a cavity of a mold in which a twisted injection hole forming pin is arranged, and the moisture of the slurry is absorbed into a porous mold to form a solidified part. Then, the twisted injection hole forming pin was pulled out from the solidified part by twisting at a predetermined angle to produce a chip molded body having a twisted injection hole. The formed twisted nozzle hole can maintain its twisted hole shape and can be manufactured accurately, reliably, and with high precision. Moreover, since the nozzle holes are formed in a twisted shape, it is possible to inject with a good spray pattern that improves air entrainment that improves the combustion form.

[Brief explanation of the drawing]

FIG. 1 is a schematic cross-sectional view showing an example of the shape of a nozzle hole formed by the method for manufacturing an injection nozzle according to the present invention.

FIG. 2 is an enlarged view of the nozzle hole in FIG. 1 viewed from the nozzle hole direction.

FIG. 3 is a schematic perspective view showing a nozzle tip of the injection nozzle in FIG. 1;

FIG. 4 is a schematic cross-sectional view showing an embodiment of a molding apparatus that can accomplish the injection nozzle manufacturing method according to the present invention.

FIG. 5 is an enlarged cross-sectional view of a main part of the molding apparatus shown in FIG. 4;

[Explanation of symbols]

1 Mold 3 Cavity 5　　　Torsion nozzle hole forming pin 7 Solidified part 9 Porous type 14 Core (forming pin) 17 Twisted nozzle hole 19 Nozzle sack 20 Nozzle tip 21 Entrance 22 Exit

Claims (4)

[Claims] 1. An injection nozzle characterized by having an injection hole twisted in the flow direction. 2. The injection nozzle according to claim 1, wherein the injection hole has a cross-sectional shape of a rectangle or an ellipse. 3. The injection nozzle according to claim 1, wherein a surrounding portion forming the injection hole is made of ceramics. 4. A step of injecting slurry into a cavity of a mold in which a pin for forming twisted injection holes is arranged, a step of absorbing water in the slurry into a porous mold to form a solidified part,
a step of pulling out the twisted injection hole forming pin from the solidified part while twisting it at a predetermined angle to produce a chip molded body; a step of baking the dry and solidified chip molded body to produce a chip sintered body; and a method for manufacturing an injection nozzle, comprising the steps of joining the chip sintered body to a nozzle body.