JP2982240B2 - Manufacturing method of fuel injection nozzle - Google Patents

Description

The present invention relates to, for example, a method for manufacturing a fuel injection nozzle for injecting fuel into a combustion chamber from an injection hole exposed in the combustion chamber.

[Conventional technology]

Conventionally, a fuel injection nozzle for spraying fuel into a combustion chamber has, for example, the structure shown in FIG. The fuel injection nozzle mainly includes a nozzle body 20, a plurality of injection holes 22 formed at the tip of the nozzle body 20, and a needle valve 21 for opening and closing the injection holes 22. The nozzle body 20 is made of a metal material, and includes a cylindrical body upper portion 24 and a cylindrical body distal end portion 25 whose distal end is sealed. A fuel supply passage 23 is formed between the inner peripheral surface of the cylindrical body upper portion 24 and the outer peripheral surface of the needle valve 21. Further, a plurality of injection holes 22 are formed in the distal end portion 25 of the cylindrical body. These injection holes 22 are opened and closed when the needle valve 21 moves up and down so that the tapered surface 26 at the distal end of the needle valve 21 comes into contact with and separates from the tapered surface 27 of the cylindrical body distal end 25.

As a fuel injection nozzle for an internal combustion engine,
There is one disclosed in Japanese Patent Publication No. 122778. The fuel injection nozzle of the internal combustion engine has a valve seat portion in which a conical surface at the tip of a needle valve disposed inside the nozzle body is seated, and a plurality of injection holes are formed in the valve seat portion. Each of the holes is made of a ceramic material, and these ceramic materials are fitted to the valve seat of the nozzle body by shrink fitting.

[Problems to be solved by the invention]

By the way, in the fuel injection nozzle, with respect to the injection hole 22 formed at the cylindrical end portion 25, the injection hole diameter and the number of injection holes are conditions that greatly affect the combustion state, and the determination of these various conditions for the injection hole is It is an important factor in improving engine performance in relation to engine performance. It is a known element that not only the nozzle diameter and the number of nozzles but also the shape of the nozzle such as the shape and the angle of the nozzle greatly influence the combustion. Conventionally, when the injection port of a fuel injection nozzle is formed in a shape other than a circle, a hole is formed in the nozzle body using a laser processing machine or an electric discharge machine.

However, in the case of laser processing by a laser processing machine, an appropriate shape can be obtained on the laser irradiation surface, but on the surface opposite to the laser irradiation surface, there is a problem that it is difficult to process into a predetermined nozzle shape. ing. In particular, it has been extremely difficult with the conventional injection hole forming method to form an injection hole having a fine shape other than a circle, that is, an irregular shape. For example, by changing the shape of the injection hole of the fuel injection nozzle from a conventional circular shape to a deformed shape such as a square shape, the velocity distribution of the spray particles can be changed and the intake of air can be improved. Further, when the injection hole has a complicated shape, for example, when the injection hole has a round shape on the side of the needle valve seat, that is, an expanded shape, it is extremely difficult to manufacture.

In the fuel injection nozzle disclosed in Japanese Utility Model Application Laid-Open No. 58-122778, the nozzle body and the ceramic pipe are fixed by shrink fitting due to a difference in thermal expansion. However, since the tip of the nozzle located in the combustion chamber is exposed to a high temperature, there is a problem that there is a high risk that only the pipe will be detached from the nozzle body by the ejection pressure during use. Also, when a ceramic pipe is made of a material having the same coefficient of thermal expansion as the nozzle body and only the nozzle body is heated and shrink-fitted, the ceramic pipe is damaged by thermal shock due to the temperature difference at the time of shrink-fitting. Or, since the weight of the ceramic pipe is very small, even if the nozzle body touches even a little during shrink fitting, the temperature of the ceramic pipe rises instantaneously, there is a risk of biting into the nozzle body, and the injection hole is small. Therefore, in order to fit by shrink fitting, the dimensional accuracy between the pipe forming the injection hole and the hole of the nozzle body becomes severe, processing is difficult, and furthermore, the pipe and the nozzle body must be chemically bonded. Is not possible and has problems.

An object of the present invention is to solve the above-described problem, and it is very easy to form a shape of an injection hole as well as a circular shape, an elliptical shape, an irregular shape such as a square shape,
Extrusion molding method of ceramic or metal powder composition, forming a pipe to form injection holes by press molding method, etc.
After pre-firing the molded pipe, the pre-fired pipe is placed in a molding die of the nozzle body, and a ceramic or metal powder composition is poured into the molding die and cured to form a nozzle body molded body. Another object of the present invention is to provide a method of manufacturing a fuel injection nozzle for integrally firing the nozzle body molded body and the pre-fired pipe.

[Means for solving the problem]

The present invention is configured as follows to achieve the above object. That is, the present invention provides a process of forming a composition of ceramic or metal powder into a pipe having a predetermined shape injection hole and pre-firing, a method of forming a pipe between an outer molding die and an inner molding die which are arranged in a spaced state. Disposing the pipe at a predetermined position across the gap of the nozzle, forming a nozzle body by pouring and hardening a ceramic or metal powder composition into the gap between the outer mold and the inner mold. The present invention relates to a method for manufacturing a fuel injection nozzle, comprising: a step of forming a body; and a step of integrally firing the nozzle body formed body and the prefired pipe.

Further, in this method for manufacturing a fuel injection nozzle, the shape and / or size of the hole formed in the pipe is different between the outside and the inside.

[Action]

The method of manufacturing a fuel injection nozzle according to the present invention is configured as described above, and operates as follows. That is, in this method of manufacturing a fuel injection nozzle, a pipe constituting an injection hole is preliminarily molded and calcined, the pipe is arranged at a predetermined position in a molding die of a nozzle body, and the composition is poured into various molding dies. The nozzle body is molded by pouring, and then the nozzle body molded body and the prefired pipe are integrally fired, so that the pipe does not bite into the nozzle body, and the pipe may be damaged by thermal shock. In addition, the pipe is securely and firmly fixed to the nozzle main body, and the phenomenon that the pipe is detached from the nozzle main body due to the ejection pressure during use does not occur.

Further, since the pipe is manufactured in advance separately from the nozzle body, the shape of the hole formed in the pipe itself is not limited to a circular shape, but may be an elliptical shape, an irregular shape such as a square shape. It can be freely selected and easily and accurately manufactured, and the size and number of holes, the position of holes, and the number of positions can be selected as desired. Can be formed.

〔Example〕

Hereinafter, an embodiment of a method for manufacturing a fuel injection nozzle according to the present invention will be described with reference to the drawings.

An embodiment of a method for manufacturing a fuel injection nozzle according to the present invention will be described with reference to FIGS. 1, 2, and 3. FIG. FIG. 1 is an explanatory view showing a middle of a process for achieving the method of manufacturing the fuel injection nozzle, FIG. 2 is an explanatory view showing a middle of a process of the manufacturing method of the fuel injection nozzle, and FIG. FIG. 3 is a cross-sectional view taken along a line III-III in FIG. 2 illustrating an example of an injection hole formed by a method of manufacturing an injection nozzle.

The method for manufacturing a fuel injection nozzle according to the present invention mainly includes a step of molding a composition of ceramics or metal powder into a pipe 3 having an injection hole 4 having a predetermined shape, degreased and pre-fired, and arranged in a spaced state. Disposing the calcined pipe 3 at a predetermined position across the gap 5 between the outer molding die 2A and the inner molding die 2B, the gap 5 between the outer molding die 2A and the inner molding die 2B. A step of casting a ceramic or metal powder composition 6 into a nozzle and curing the same to form a nozzle body molded body 1;
Next, the nozzle body molded body 1 and the pre-fired pipe 3 are integrally fired. Here, pipe 3
As a ceramic material for forming, a powder of silicon nitride, silicon carbide or alumina can be selected in addition to zirconia.

In the method of manufacturing this fuel injection nozzle, as described above, since the pipe 3 itself is preliminarily calcined and formed, the diameter, shape, arrangement angle, and size of the injection hole 4 formed in the pipe 3 are desired. Can be selected and formed in advance according to Moreover, the injection hole 4 formed in the pipe 3
It can be very easily and accurately processed into a given shape, size and the like. For example, for example, in the method of manufacturing the fuel injection nozzle, the injection hole 4 formed in the pipe 3
The shape and / or size of the needle valve seat can be made different between the inside that is the needle valve seat portion and the outside that is exposed to the combustion chamber. In addition, the shape of the injection hole 4 can be extremely easily formed not only in a circular shape but also in an irregular shape such as a square shape.

Further, in the method of manufacturing the fuel injection nozzle, since the nozzle body molded body 1 and the preliminarily fired ceramic pipe 3 are integrally fired, the pipe 3 forming the injection hole portion is extremely firmly and easily fixed to the nozzle body. can do.

In some cases, in the method of manufacturing the fuel injection nozzle, when the joining force between the nozzle body and the pipe is insufficient, an uneven portion or a tapered surface is formed on the outer surface of the pipe, and the calcined pipe is formed into a nozzle body molded body. By integrally baking, the nozzle body and the pipe can be firmly fixed not only by chemical bonding but also by mechanical bonding.

Hereinafter, a method for manufacturing a fuel injection nozzle according to the present invention will be specifically described.

Example 1 In this method for manufacturing a fuel injection nozzle, as shown in FIG. 3, a circular orifice 4 having a predetermined shape was formed by extruding a ceramic or metal powder composition as a first step. It is extruded into a pipe 3 provided, and the molded body of the pipe 3 is degreased and calcined. Next, as shown in FIG. 1, the pre-fired pipe 3 is placed at a predetermined position and at a predetermined position across a gap 5 between the outer molding die 2A and the inner molding die 2B arranged in a spaced state. At an angle. After the calcined pipe 3 is placed in the gap 5 between the outer mold 2A and the inner mold 2B, the gap 5 between the outer mold 2A and the inner mold 2B is formed.
Then, as shown in FIG. 1, a composition 6 of ceramic or metal powder is poured, and the composition 6 is cured. When the composition 6 is cured, as shown in FIG. 2, the nozzle body molded body 1 in a state where the pipe 3 is disposed at a predetermined position.
Is molded. Next, the nozzle body molded body 1 and the pre-fired pipe 3 are integrally fired to form a nozzle body of a fuel injection nozzle having an injection hole 4.

At this time, the contraction rate of the pipe 3 forming the injection hole is 10%,
In addition, the shrinkage ratio of the nozzle body molded body 1 forming the nozzle body is adjusted to 16%, and the difference in the shrinkage ratio is used for firing,
The pipe 3 was fitted and joined to the nozzle body.

A spray test was performed using the fuel injection nozzle manufactured by the method for manufacturing the fuel injection nozzle. Although the injection pressure in the spray test was 1000 kgf / cm ² , the phenomenon that the pipe 3 forming the injection hole portion came off from the nozzle body and the phenomenon of fuel leakage from the boundary surface between the nozzle body and the pipe did not occur.

Embodiment 2 Another embodiment of the method for manufacturing a fuel injection nozzle according to the present invention will be described with reference to FIGS. 4 and 5. FIG. FIG. 4 is an explanatory view showing the middle of the steps of the method of manufacturing the fuel injection nozzle, and FIG. 5 is another line VV of FIG. 4 showing another example of the injection hole formed by the method of manufacturing the fuel injection nozzle. FIG.

In this example, the composition of ceramic or metal powder was extruded by the extrusion molding method in the same manner as in the above step.
As shown in the figure, the molded product is extruded into a pipe 3 having a circular injection hole 4 having a predetermined shape, and the molded body of the pipe 3 is degreased and calcined. Next, as shown in FIG. 4, the injection hole 4 on one end side of the pre-fired pipe 3 is processed into a shape having a trumpet-shaped expansion, that is, a shape of a tapered injection hole 4T in an expanded state. That is, processing is performed such that the size of the hole diameter of the injection hole 4 formed in the pipe 3 is different between the inside on the needle valve seat portion side and the outside on the combustion chamber side. Next, a fuel injection nozzle was manufactured in the same process as in the above embodiment.

-Embodiment 3- Still another embodiment of the method for manufacturing a fuel injection nozzle according to the present invention will be described with reference to FIGS. 6 and 7. FIG. FIG. 6 is an explanatory view showing a step in the process of the method for manufacturing a fuel injection nozzle, and FIG. 7 is a view showing still another example of an injection hole formed by the method for manufacturing a fuel injection nozzle. It is sectional drawing in VII.

In this example, as a first step, a composition of ceramic or metal powder was press-formed into a pipe 3 having a square injection hole 4S as shown in FIG. Is degreased and calcined. Next, a fuel injection nozzle was manufactured in the same process as in the first embodiment. In this embodiment, the shape of the injection hole 4S formed in the pipe 3 is previously formed into various shapes such as a square shape.

〔The invention's effect〕

The method for manufacturing a fuel injection nozzle according to the present invention is configured as described above, and has the following effects. That is, this method of manufacturing a fuel injection nozzle includes a step of forming a composition of ceramic or metal powder into a pipe having a predetermined shape of injection holes and pre-firing, a method in which an outer molding die and an inner molding die are arranged in a spaced state. Arranging the pipe at a predetermined position across a gap between the molding die, pouring a composition of ceramics or metal powder into a gap between the outer molding die and the inner molding die, and curing. Forming the nozzle body molded body, and then integrally firing the nozzle body molded body and the pre-fired pipe, it is possible to previously form an injection hole of any shape in the pipe itself, Therefore, a fuel injection nozzle having an injection hole of a complicated shape such as an injection hole having a different size or shape between the combustion chamber side and the needle valve seat side and an injection hole having an irregular shape other than a circular shape can be easily manufactured. Can be manufactured to

In addition, the integration of the pipe and the nozzle body forming the injection hole portion adjusts the shrinkage rate during firing of the pre-fired pipe and the nozzle body molded body forming the nozzle body, and reduces the difference in the appropriate shrinkage rate. By using the difference, the two can be simultaneously fitted at the time of integral firing, and the two can be fixed very firmly. Further, at this time, the two can be joined by utilizing the pressing force generated between the calcined body of the pipe and the ceramic composition and the temperature at the time of firing. Therefore, the pipe of the injection hole portion and the nozzle body can be firmly and securely bonded both chemically and mechanically, and the pipe forming the injection hole does not fall out of the nozzle body by the fuel pressure.

In addition, since the pipe in the injection hole portion that has been pre-fired can be machined, if a shape that is difficult with a general molding method is required, a new processing is performed at this time, and then the pipe and the nozzle body are processed. It is also possible to perform integral firing with the molded body. That is, since the pipe is manufactured in advance separately from the nozzle body, the shape of the hole formed in the pipe itself is not limited to a circular shape, but may be an elliptical shape, an irregular shape such as a square shape. It can be freely selected and easily and accurately manufactured. In addition, the size and number of holes, the positions of the holes, the number of positions can be selected as desired,
Injection holes of irregular shapes such as quadrangular shapes can be formed easily and efficiently, a favorable combustion state in the combustion chamber can be obtained, and engine performance can be improved.

Further, in this method for manufacturing a fuel injection nozzle, the pipe is securely and firmly fixed to the nozzle body without the pipe being bitten by the nozzle body, without being damaged by a thermal shock, Further, the phenomenon that the pipe is detached from the nozzle body due to the ejection pressure during use does not occur.

[Brief description of the drawings]

FIG. 1 is an explanatory view showing a step in the process of achieving the method of manufacturing the fuel injection nozzle, FIG. 2 is an explanatory view showing a step in the step of the method of manufacturing the fuel injection nozzle, and FIG. Second example showing an injection hole formed by a method for manufacturing a nozzle
FIG. 4 is a cross-sectional view taken along the line III-III in FIG. 4, FIG. 4 is an explanatory view showing a step in the process of the method for manufacturing the ceramic nozzle, and FIG. 4 is a cross-sectional view taken along line VV in FIG. 4, FIG. 6 is an explanatory view showing the middle of the steps of the method of manufacturing the ceramic nozzle, and FIG. 7 is a view further illustrating the injection holes formed in the fuel injection nozzle of FIG. FIG. 8 is a sectional view taken along line VII-VII in FIG. 6 showing another example, and FIG. 8 is a schematic view showing an example of a conventional fuel injection nozzle. 1 ... nozzle body molded body, 2A ... outer molding die, 2B ... inner molding die, 3 ... pre-fired pipe, 4 ... injection hole, 4T ...
Taper injection hole, 4S ... Square injection hole, 5 ... Gap,
6 Composition.

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁶ , DB name) F02M 61/16-61/18

Claims (2)

(57) [Claims] 1. A step of forming a composition of ceramic or metal powder into a pipe having a predetermined shape injection hole and pre-baking, wherein a step of forming a pipe between an outer forming die and an inner forming die arranged in a spaced state. Disposing the pipe at a predetermined position across a gap, pouring a composition of ceramics or metal powder into a gap between the outer mold and the inner mold, and curing the composition to form a nozzle body Forming a fuel injection nozzle, and then integrally firing the nozzle body molded body and the prefired pipe. 2. The method for manufacturing a fuel injection nozzle according to claim 1, wherein the shape and / or size of the injection hole formed in the pipe is different between the outside and the inside.