JPS5947124B2 - □/Method for forming a shield or heat shield structure for an engine or exhaust system□/ - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a sound and heat insulation structure for an engine exhaust system.

For the purpose of sound and heat insulation, the exhaust system of an automobile, i.e., exhaust manifold, exhaust muffler, thermal reactor, exhaust pipe, silencer, catalytic converter, etc., is partially or completely covered with a heat shield plate (or shield plate). It is already known to form structures.

This sound-insulating, heat-insulating (or shielding) double structure is used in cases where the exhaust system, for example, the exhaust pipe itself, constitutes a part (inner member) of the double structure, and in cases where it is installed between two members separately from the exhaust system. There are cases in which a double structure is formed with a gap provided (for example, a double structure heat shield plate that covers the periphery of a catalytic converter).

In either case, a void is provided in the double structure, and the void is filled with a known heat insulating material.
It requires a relatively large number of processing steps and labor to complete the product, and has the disadvantage of being high in cost and not suitable for mass production.

For example, in JP-A-48-102107.

A ceramic layer is formed on one inner wall of a structure consisting of two walls in which a heat insulating layer is to be formed, and silicate-based mineral grains that expand at a high level are inserted into the gap between the ceramic layer and the other inner wall surface of the structure. However, a method for manufacturing a heat insulating structure is disclosed in which the structure is heated to 300° C. or higher to expand the mineral grains and form a second ceramic layer.

The heating method for the mineral grains in this invention is as follows:
One task is extremely difficult as it uses a solid heating furnace.

Moreover, since two ceramic layers are formed in the void, there are many steps required to complete the product, resulting in high cost and poor mass production.

On the other hand, Japanese Patent Publication No. 49-4536 discloses that an expandable paint as a heat protection paint that forms a soluble protective layer is applied to the metal inside a jet engine. Even with this invention, the sound insulation and heat insulation of the exhaust system of the engine, which requires less processing steps and labor and is highly suitable for mass production, must be installed inside the metal that is exposed to high temperatures. Structures are unobtainable.

The present invention has an extremely simple structure and work process, and
The object of the present invention is to provide a sound-insulating and heat-insulating structure that can be mass-produced at low cost, and examples thereof will be described below with reference to the drawings.

In each figure, common symbols are used for exhaust pipes, voids, and foaming fireproofing paint.

In FIGS. 1 and 2, 1 is an exhaust pipe that is an exhaust system of an engine, 2 is a heat shield plate that covers a part of the exhaust pipe, and a gap 3 is formed between the two.

The inner member of such a double structure, that is, the outer surface (the surface on the gap 3 side) covered by the heat shield plate 2 of the exhaust pipe 1 in this example,
A foamable fireproofing paint 4 is applied in advance.

Such a double structure is assembled into a vehicle body, for example, as an exhaust system of an automobile engine.

After the engine is operated, the temperature of the exhaust pipe 1 rises due to the passage of exhaust gas, and by receiving this heat indirectly, the paint foams and fills the void 3, forming a sound-insulating and heat-insulating structure. .

Figures 3 and 4 show the state after foaming.
Reference numeral 5 indicates the paint layer (foamed product) after foaming.

FIG. 5 shows a catalytic converter, and numeral 6 is a case housing the catalyst, which is installed inside the main body γ.

A foamable fireproofing paint 4 is applied to the outer surface (the surface on the gap 3 side) of the main body 7, and a cover 8 is attached to the outside with the gap 3, forming a double structure.

This is the assembled state, and after the engine is started, the paint 4 automatically foams due to the heat of the catalytic converter itself, and the air gap 3
to form a sound-insulating and heat-insulating structure.

In addition, foaming fire prevention paint is a type of paint that looks the same as a normal paint film, but when the ambient air temperature exceeds a certain value, the paint film becomes several times to about 10 times thicker. As a specific example, for example, sodium silicate powder (water content 42~
1%) as water-based paint.

Synthetic resin Latinx emulsions, dispersed in oil-based paints, paints made by adding various organic phosphorus compounds to epoxy resins, and other foaming agents such as ammonium polyphosphate, sulfonamides, and carbonizable materials. Many things such as paint are known.

These may be used appropriately depending on the conditions of implementation.

As described above, the present invention provides an exhaust gas passage member such as an exhaust pipe 1. A foaming fireproofing paint is interposed between the catalytic converter main body 7 and the members surrounding it, such as the heat shield plate 2 and the cover 8, which are attached to the engine main body so that engine exhaust gas is guided to the passage member, and the engine is operated. By doing so, the foamable fireproofing paint is foamed by the heat of the exhaust gas passing through the passage member, and the foamable composition alone fills the gap to form a sound-insulating and heat-insulating structure for the engine exhaust system. There is no need to manufacture and incorporate the materials separately, and the processing process is extremely simplified, resulting in benefits such as low cost and significantly improved mass productivity.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view showing an embodiment of the present invention, FIG. 2 is a sectional view taken along the line H-■ in FIG. 1, and FIG. 3 is a sectional view showing another operating state of FIG. 4 is a sectional view taken along the +v-iv arrow in FIG. 3, and FIG. 5 is a longitudinal sectional view showing another embodiment of the present invention. 1...exhaust pipe, 2...heat shield plate, 3...
...Void, 4...Foaming fire prevention paint.

Claims (1)

[Claims] 1. A foamable fireproofing paint is interposed in the gap between an exhaust gas passage member and a member that covers its surroundings, and it is attached to the engine body so that engine exhaust gas is guided to the passage member, and when the engine is operated, the passage member is closed. A method for forming a sound-insulating/heat-insulating structure for an engine exhaust system, characterized in that the foamable fireproofing paint is foamed by the heat of passing exhaust gas, and the foamed product alone fills the gap.