JPS5917495Y2 - Cylindrical insulation structure casting - Google Patents

Description

[Detailed description of the invention] The present invention relates to the improvement of the structure of a cylindrical heat insulating structure casting.In particular, it has a new structure in which ceramics and/or cast-in metal are not damaged during production, and the product is a cylindrical heat insulating structure. When used as structural castings such as exhaust pipes of internal combustion engines,
It is an object of the present invention to provide a cylindrical heat-insulating structural casting having a structure that not only increases the exhaust gas temperature but also significantly reduces the temperature rise outside the tube.

Tubular parts that require heat insulation are required for exhaust passages of internal combustion engines.

FIG. 1 is a vertical sectional side view of a conventional ceramic featured exhaust pipe, and FIG. 2 is a vertical sectional side view of a part (exhaust port) of a conventional ceramic featured cylinder head.

These tubular structure castings are intended to raise the exhaust gas temperature and purify the exhaust gas by increasing the heat insulation properties of the exhaust system parts of internal combustion engines. It has a structure in which a metal material 02 for an exhaust pipe or an exhaust port, for example, cast iron, is cast on the outer peripheral surface.

However, when these conventional cylindrical heat-insulating structural castings were manufactured using the conventional cast-in method, there was a drawback that the ceramic molded body and/or the cast-in metal were damaged due to thermal shock during pouring and shrinkage during solidification and cooling. .

The inventors of the present invention have conducted intensive research into eliminating the defects in the production of the conventional cylindrical heat-insulating structure castings, and have determined that the ceramic molded body should be configured in such a way that thermal shock and shrinkage during production can be alleviated. Through this research, he discovered that the drawbacks of the conventional technology could be completely overcome, and based on that knowledge, he completed the present invention.

In other words, the present invention is a cylindrical heat insulating body formed by casting metal on the outside of a cylindrical ceramic which is integrally formed with a heat insulating filler interposed between the divided surfaces of a ceramic molded body that is formed into at least two parts. It concerns structural castings.

Hereinafter, the present invention will be explained in more detail with reference to the drawings.

Figure 3 is a cross-sectional side view of the cylindrical ceramic (for example, for exhaust pipes) that is the main part of the cylindrical heat insulating structure casting of the present invention;
The figure is a cross-sectional side view of the rectangular cylindrical ceramics (for example, for exhaust ports) that is the main part of the cylindrical heat-insulating structure casting of the present invention. Figures 5 and 6 illustrate the manufacturing status of the cylindrical heat-insulating structure casting of the present invention. 5 is a cross-sectional side view of the mold for producing a cylindrical heat-insulating structure casting according to the present invention, FIG. 6 is a vertical cross-sectional side view of FIG. 5 viewed from the direction of arrow VI-VI, and FIG. FIG. 2 is a cross-sectional side view of the devised cylindrical heat insulating structure casting.

Hereinafter, with reference to FIGS. 3 to 7, a method for manufacturing the cylindrical heat-insulating structure casting of the present invention will be described.

Figures 3 and 4 show the cylindrical ceramics and rectangular cylindrical ceramics that are the main parts of the invented cylindrical heat insulating structure casting. Explain.

In Fig. 3, 1A and 1B are semi-cylindrical ceramics having dividing surfaces that match each other, and these may be manufactured by cutting the cylindrical ceramic along a plane passing through the axis, or they may be made in advance by cutting the cylindrical ceramics along a plane passing through the axis. It may also be formed into a cylindrical shape.

Ceramics such as silicon nitride, alumina, and zirconia can be used as the material.

Note that the shape of the dividing planes to be matched may be a waveform, an uneven shape, or the like.

Here, an example of two divisions will be explained, but it goes without saying that it may be divided into three or four divisions if necessary.

3A and 3B are the semi-cylindrical ceramics 1A, respectively.
and a heat insulating filler interposed between the dividing surface or the surface to be joined of 1B, which is, for example, asbestos fibers such as asbestos string or asbestos ribbon coated with resin-based molding glue.

With this, the semi-cylindrical ceramics 1A and 1B are joined to form the cylindrical ceramic 1.

Similarly, in the case shown in Fig. 4, the semi-cylindrical ceramic IIA
and 11B are joined with heat insulating fillers 13A and 13B to form a rectangular cylindrical ceramic 11.

Next, a situation in which the cylindrical ceramic 1 is disposed in a mold to produce the cylindrical heat insulating structure casting of the present invention will be described with reference to FIGS. 5 and 6.

5 and 6, 4 is a mold divided into upper and lower parts, 5 is a cylindrical mold cavity bored in the joint surface of the mold 4, and 6 is both ends of the mold cavity 5. A supporting member is disposed in the cylindrical ceramic body 1 and a part thereof is inserted into the inner circumferential surface of both ends of the cylindrical ceramic body 1, thereby forming a casting cavity between the outer circumferential face of the cylindrical ceramic body 1 and the mold cavity 5. 5A is formed.

Reference numeral 7 denotes a sprue drilled so as to communicate from the side from the upper part of the mold 4 to the casting cavity 5A, and numeral 8 denotes a sprue bored in the upper part of the mold 4 so as to communicate with the mold cavity 5. .

From the hot water lower of the mold configured in this way to the casting cavity 5A
By pouring molten cast iron, it is possible to produce a cylindrical heat-insulating structure casting 21 of the present invention, in which a cylindrical ceramic 1 is cast with cast iron 2, as shown in FIG.

Similarly, a rectangular tube-shaped heat insulating structure casting can also be manufactured.

Note that resin-based molding glue alone can be used as an insulating material, but its viscosity decreases at high temperatures, making it impossible to maintain the gaps between the ceramics to alleviate shrinkage, causing the ceramics to adhere to each other at high temperatures and solidify. This is not very preferable because the shrinkage stress during cooling may damage the ceramic and/or metal.

In addition, asbestos fiber alone makes it difficult for ceramics to adhere to each other, which is also not very desirable.

A combination of resin-based molding glue and asbestos fiber is suitable as the heat-insulating filler of the present invention.

Next, the effects of the cylindrical heat insulating structure itself of the present invention will be described.

When the exhaust system parts of an internal combustion engine are manufactured as cylindrical heat insulating structure castings as described above, the exhaust gas temperature will be lower than the normal exhaust gas temperature (8
00 to 900°C), which is effective in purifying exhaust gas and improving fuel efficiency, and the temperature rise on the outside of the exhaust pipe is small. This has the effect of eliminating the need for a jacket, and also contributes to reducing the weight of the engine.

[Brief explanation of drawings]

Figures 1 and 2 are vertical sectional side views of a part of a conventional ceramic exhaust and cylinder head, and Figures 3 and 4 are
The figure shows cylindrical ceramics (for example, for exhaust pipes) and rectangular cylindrical ceramics (for example,
For example, for the exhaust port), the cross-sectional side view, FIGS. 5 and 6,
This is a diagram explaining the production status of the cylindrical heat insulating structure casting according to the present invention.
The figure is a cross-sectional side view of the mold for producing cylindrical heat-insulating structure castings according to the present invention.
6 is a longitudinal cross-sectional side view of FIG. 5 viewed from the direction of arrow VI-VI, and FIG. 7 is a cross-sectional side view of the cylindrical heat insulating structure casting of the present invention.

Claims (1)

[Scope of utility model registration request] A cylindrical heat-insulating structural casting made by casting metal on the outside of a cylindrical ceramic body formed integrally with a heat-insulating filler interposed between the divided surfaces of a ceramic molded body formed into at least two parts.