JPH0578645B2 - - Google Patents

Description

[Detailed description of the invention]

(Industrial Application Field) The present invention is used in the technical field of preheating combustion chambers in engines, and mainly relates to the manufacturing technology of pre-chambers. (Prior Art) A pre-chamber structure serving as a preheating chamber for a diesel engine has been well known. In addition, in order to improve the heat resistance of the sub-chamber structure, there is also an idea of molding the sub-chamber with ceramic material. For example, Utsukai Showa 54-
The auxiliary chamber disclosed in Publication No. 77802 is made by integrating an inner cylinder made of ceramic material and surrounding the outer periphery with cast iron. However, it requires casting equipment having the structure of the above-mentioned invention, and there is a problem in workability. (Object of the Invention) Prior to the completion of this invention, the member (inner cylinder) forming the sub-chamber was made of ceramics, a heat insulating material was provided annularly around the outer periphery of this member, and the member (outer cylinder) forming the sub-chamber was provided with a ring shape around the outer periphery of the member. When we prototyped a structure in which a cylinder was covered with a sintered metal material, we found that the sintered metal material contracted unevenly in the axial and diametrical directions, centering on areas where the inner and outer cylinders were in strong contact. , a misalignment occurs between the sintered metal material (outer cylinder) and the sub-chamber member (inner cylinder),
It was found that the dimensional accuracy of the external shape could not be maintained, which was a problem when assembling it into the engine. For example, in FIG. 1 showing the manufacturing process of the present invention, the flatness of the shoulder surface 2d of the sintered metal outer cylinder 2 and the bottom surface of the ceramic inner cylinder 1 is distorted, making it impossible to ensure the accuracy of the combustion chamber during assembly. This causes problems. In this invention, an engine having a structure that has a sufficient heat insulation effect and a member (inner cylinder) that forms the auxiliary chamber and a sintered metal member (outer cylinder) that covers this member are tightly joined without shifting. The purpose of the present invention is to provide a method for manufacturing an antechamber. (Structure of the Invention) The manufacturing method of the present invention is to fit an inner cylinder made of ceramics into an opening of an outer cylinder preformed with a sintered material, and fill the gap between the outer cylinder and the inner cylinder in the opening. In this method, a sub-chamber is manufactured by press-fitting a metal coupling ring with a wedge-shaped cross section to be integrated with the outer cylinder at the sintering temperature of the outer cylinder, fixing the space between the inner and outer cylinders, and then heating and sintering. The effect of this invention is that the inner cylinder and the outer cylinder are heated and sintered while being restrained at the opening of the outer cylinder by the above manufacturing method, so that the outer cylinder is partially uneven due to the characteristics of the sintered material. Even if the constraint part contracts in a fixed state, the dimensional relationship between the inner cylinder and the outer cylinder, for example, the parallelism between the bottom surface of the inner cylinder and the shoulder surface of the outer cylinder, can be maintained with good accuracy. It can be finished with. (Example) Hereinafter, an example of the present invention will be described in detail with reference to the drawings. The inner cylinder 1, which is a component of the subchamber, is made of ceramics (for example, silicon nitride), and is divided into a lower half 1a and an upper half 1b. The lower half portion 1a is formed into a substantially cylindrical shape with a bottom, and the upper half portion 1b is formed into a substantially hemispherical shape. A nozzle 1c is opened at the bottom of the lower half 1a, and a fuel nozzle 1d is opened at the upper half 1b.
is opened. As shown in FIG. 1, the outer cylinder 2, which is a component of the sub-chamber, is pre-formed from iron-based sintered material into an inner cylinder shape with a dome-shaped upper end and an open lower end. This preliminary formation may be performed by powder compaction at room temperature, but it is desirable to further increase the strength by pre-sintering, as this will facilitate handling during the processing process. An open end 2a is formed at the lower end of the outer cylinder 2, and the inner cylinder 1 can be fitted therein after the above-mentioned preliminary formation. A globe lug opening 2b and a fuel injection valve opening 2c are opened in the upper wall portion of the outer cylinder 2. Each of the inner cylinder 1 and the outer cylinder 2 has a stepped portion so that when the inner cylinder 1 is fitted into the outer cylinder 2, an annular space is formed in the outer cylinder of the inner cylinder 1 as a heat insulating part forming part 3. It is formed. In the gap C between the inner edge of the opening 2a of the outer cylinder 2 and the outer edge part 1e of the lower half 1a of the inner cylinder 1 corresponding to this part,
As shown in FIG. 2, a coupling ring 4 having a wedge-shaped cross section and a partially cut annular ring is press-fitted. The cut portion 4a of the coupling ring 4 is for interference during press-fitting. The coupling ring 4 is made of a metal that is integrated with the outer cylinder 2 at the sintering temperature of the outer cylinder 2 during sintering.
In this case, it is made of iron or nickel metal. When the inner cylinder 1 manufactured as described above is fitted into the outer cylinder 2, an appropriate amount of ceramic fiber material 5, such as alumina silicate fiber material, is filled into the heat insulating portion forming region 3. The coupling ring 4 inserted into the gap between the opening 2a and the outer edge portion 1e of the lower half 1a of the inner cylinder is further press-fitted to fix the inner cylinder 1 and the outer cylinder 2. At this time, the shoulder surface 2d of the outer cylinder 2 and the bottom surface 1 of the lower half part 1a of the inner cylinder 1
In order to ensure accurate parallelism with f, the lower half 1 of the inner cylinder 1
A and the upper half part 1b are accurately aligned so that the joint surfaces 1g of the upper half part 1b are not misaligned left and right. The bottom surface 1f of the inner cylinder 1 (see FIG. 1) for assembly as described above is placed on the stand 6 to complete the preparation for the sintering process. When the outer cylinder 2 is heated (approximately 1000°C) to sinter the outer cylinder 2 in this state, the outer cylinder 2 and the coupling ring 4 are combined and integrated, and the outer cylinder 2 is shrunk, except for the area where the heat insulating part 3 is formed. That is, ceramic fiber material 5
The inner side of the outer cylinder 2 tightens the outer side of the inner cylinder 1 and is integrated with the outside of the inner cylinder 1 at a portion where there is no . At this time, even if the lower half 1a and the upper half 1b of the inner cylinder 1 are not particularly joined, the inner cylinder 1 is integrated with the outer cylinder 2 by the press-fitting of the coupling ring 4, and the inner cylinder 1 is integrated with the outer cylinder 2. The bottom surface 1f of is placed on the stand 6, and the outer cylinder 2 is sintered and contracted in a free state. On the other hand, when a sintered material is sintered, the shrinkage phenomenon is uneven depending on its shape, and the material has the characteristic of shrinking mainly in the strongly fixed parts. Therefore, in the case of this embodiment, the outer cylinder 2 contracts with respect to the bottom surface 1f, and the lower half part 1a and the upper half part 1b of the inner cylinder 1
The joint surface 1g between them does not shift, and the parallelism between the bottom surface 1f of the inner cylinder 1 and the shoulder surface 2d of the outer cylinder 2 is slightly distorted, and sintering is completed with a constant accuracy. Finally, the unnecessary parts 2e and 4b of the lower part of the outer cylinder 2 and the coupling ring 4 are removed to complete the assembly. The auxiliary chamber 7 manufactured in this manner is integrally fitted into the cylinder head 8 as shown in FIG.
Others 9 are glow plugs, 10 are fuel injection valves, 1
1 is a cylinder block, and 12 is a piston. (Test Results) Next, the results of measuring the accuracy of the completed auxiliary chamber (structure) 7 will be explained. (See the table below) Accuracy is determined by expressing the inclination dimension of the bottom surface 1f as parallelism S (mm) with the shoulder surface 2d as the reference, and the smaller the value, the better the accuracy is (see Figures 3 and 6). ). The accuracy of the subchamber 7 in the embodiment of the present invention is
Sub-chamber 17 shown in Nos. 1 to 15 and when the coupling ring 4 having the structure shown in FIG. 6 as a comparative example is not used.
The accuracy is shown in conventional product samples No. 1 to 8.

[Table] Comparing the above test results, the parallelism S of the subchamber 7 of the example of the present invention is 0.02 to 0.05 mm, and the parallelism S of the subchamber 1 of the comparative example
The parallelism S of No. 7 is 0.07 to 0.46 mm, and the one produced by the manufacturing method of the present invention is much better. Furthermore, since the sub-chamber 7 according to the manufacturing method of the present invention is made by filling the outer periphery of the inner cylinder 1 with ceramic fiber material 5,
Its insulation properties are also good. In addition to the embodiments described above, the present invention can also be modified as described below. (1) To prevent mutual rotation between inner cylinder 1 and outer cylinder 2,
It is also possible to provide recesses and recesses that engage with each other. (2) The heat insulating portion forming part 3 is formed by adding steps to both the inner cylinder 1 and the outer cylinder 2, but this can be done by providing an annular recess on the outer circumferential surface of the inner cylinder 1 or by forming a step on the inner circumference of the outer cylinder 2. It may also be formed by providing an annular recess in the surface. (3) If silicon nitride is used as the ceramic material for the inner cylinder 1, it has the advantage of being relatively resistant to thermal shock, but other materials such as zirconium oxide and silicon carbide may also be used. (Effects of the Invention) As described above, the present invention includes fitting an inner cylinder made of ceramics into an outer cylinder manufactured by preforming sintered material, and press-fitting a coupling ring with a wedge-shaped cross section into the opening gap of the outer cylinder. The sub-chamber is manufactured by fixing the cylinder so that it does not shift and then heating and sintering it to integrate it, which prevents the flat surface of the sub-chamber from shifting or tilting.
Improves accuracy when attaching a pre-chamber to the cylinder head of an engine.

[Brief explanation of the drawing]

Figures 1 to 5 show an embodiment of the present invention, and Figures 1 to 3 are central longitudinal cross-sectional side views of the subchamber (structure) for explaining each step of the manufacturing method of the subchamber of this embodiment. , FIG. 4 is a perspective view of a coupling ring, FIG. 5 is a central longitudinal cross-sectional side view of a subchamber manufactured by the manufacturing method of an embodiment of the present invention, and FIG. 6 is a comparative example of the embodiment of this invention. FIG. 3 is a central vertical sectional side view showing the subchamber. 1... Inner cylinder, 2... Outer cylinder, 2a... Opening, 4
...Coupling ring, 7...Subchamber (structure).

Claims (1)

[Claims] 1. A preformed ceramic inner cylinder is inserted into the opening of an outer cylinder preformed with a sintered material, and the sintering temperature of the outer cylinder is adjusted between the outer cylinder and the inner cylinder at the opening. A metal coupling ring having a wedge-shaped cross section that is integrated with the outer cylinder is press-fitted in the engine, and after the inner cylinder and the outer cylinder are fixed so as not to be displaced, the engine is heated and sintered. Method of manufacturing antechamber.