JPS6032070B2 - insulation structure casting - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a heat-insulating structural casting having high heat resistance.

Conventionally, exhaust gas countermeasures for internal combustion engines such as diesel engines have been broadly divided into two methods: installing exhaust purification devices such as catalytic converters and thermal reactors, and methods of increasing the temperature of exhaust gas by using adiabatic engines or heat insulating the exhaust system. can.

Among these, in order to insulate the exhaust system, an insulating exhaust pipe as shown in FIG. 1 has been proposed.

That is, a metal material (02) for an exhaust pipe, for example, cast iron, is placed on the outside of a ceramic (01) formed into a cylindrical shape. However, this method has disadvantages such as damage to the ceramic or the metal wrapping due to thermal shock during injection and shrinkage during solidification and cooling. As a solution to these problems, structural improvements have been made, such as improving the ceramic composition, inserting a buffer material between the ceramic and the metal, and creating a multilayer structure, but the drawbacks have not yet been completely eliminated. This is the current situation. The inventors of the present invention have found that they will not be damaged by heat shrinkage, etc., and will also purify the exhaust gas due to a rise in exhaust gas temperature, prevent thermal effects on the exhaust system and its surrounding parts, and prevent problems such as burns due to human contact with exhaust system parts. As a result of repeated research in order to provide a heat-insulating structural casting that can prevent the above-mentioned problems, the inventors have discovered that the above object can be achieved by disposing heat-insulating ceramics on the outside of exhaust system components, and have thus arrived at the present invention.

That is, the present invention relates to a heat-insulating structural casting characterized by casting a cylindrical metal so as to be in contact with the inner surface of a cylindrical ceramic molded body, in which the material of the ceramic molded body is fused silica-based ceramics, and the coin metal is cast iron. .

This heat-insulating structural casting is used for tubular parts that require heat insulation, such as exhaust passages for internal combustion engines. The present invention will be explained in more detail using FIGS. 2 to 6. FIG. 2 shows the basic structure of the heat insulating structure casting of the present invention, in which a metal 2 is cast inside a cylindrical ceramic molded body 1.

FIG. 3 is a diagram relating to the production of a heat-insulating structural casting according to the present invention.

That is, the outer periphery of the cylindrical ceramic molded body 1 disposed inside the coin frame 3 is hardened with molding sand 4 to form holes inside the ceramic molded body 1, and a core 5 made of molding sand is further inserted. Place it in the center of the hole. By pouring molten metal from the sprue 7 into the cylindrical cavity 6 between the ceramic molded body 1 and the core 5 thus formed, the heat-insulating structural casting shown in FIG. 2 is manufactured. be able to. If metal is cast with the ceramic molded body on the outside in this way, there is no risk of damage to the ceramic or metal due to shrinkage of the metal.
Furthermore, the gap created between the ceramic and the metal acts as an air layer and has the effect of further increasing heat insulation.

Note that the more uneven the inside of the ceramic, the stronger the mechanical bond between it and the metal, but if the inside of the ceramic is smooth or the metal has a large shrinkage, the bond between the ceramic and the metal will be strong after the metal solidifies. A gap is created between them, making them easier to separate.

Therefore, separation can be prevented by using the structures shown in FIGS. 4, 5, and 6. FIG. 4 shows a metal 2
The ceramic molded body 1 and the metal 2 are cast.
Even if there is some gap between them, the brim makes it difficult to separate them.

In FIGS. 5 and 6, the mirrored metal 2 has one or more gentle knob-shaped protrusions 28, and as in FIG. 4, there is some gap between the ceramic molded body and the metal. Even if this occurs, it becomes difficult to separate.

Simple Explanation of Drawings Figure 1 is a heat insulation side view of a conventional heat insulation structure casting;
The figure is a longitudinal side view showing the basic structure of the heat insulating structure casting of the present invention, FIG. 3 is a longitudinal side view showing an example of a mold for producing the heat insulating structure casting of the present invention, FIG. 6 is a longitudinal sectional side view showing another example of the insulating structure casting of the present invention.

Figure 1 Figure 2 Moth figure 3 om diagram Spear 5 Figure 6

Claims (1)

[Claims] 1. A heat-insulating structural casting characterized by having a cylindrical metal cast so as to be in contact with the inner surface of a shaped ceramic body.