JPH0134681Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement of an exhaust port liner for an internal combustion engine, and more particularly to an exhaust port liner for an internal combustion engine that has a heat insulating effect, prevents breakage, and has a holding force to a cylinder head.

In general, when the combustion efficiency of an internal combustion engine is improved, the exhaust gas temperature decreases, and purification by the complete combustion action of the exhaust gas by an oxidation catalyst, etc., becomes insufficient. Therefore, the exhaust pipe diameter should be It is necessary to insulate and keep the road warm, and exhaust port liners exist as one of the measures. However, since the exhaust port portion is normally cooled by cooling water, the effect of the purification catalyst may be significantly reduced due to a decrease in the temperature of the exhaust gas.

Conventionally, exhaust port liners with a stainless steel double-tube structure and port liners using ceramics have been used as a countermeasure against this problem, but in the case of the former double-tube structure stainless steel pipes, the insulation of the air insulation layer between the double pipes has been used. Although the latter port liner using a ceramic tube has a lower thermal conductivity than metal, it cannot be said that the heat insulating effect is sufficient. Therefore, in order to achieve a heat insulating effect and prevent damage to the exhaust port liner of the ceramic pipe, the outer periphery of the ceramic pipe 11 is covered with ceramic wool 12, as shown in the partial cross-sectional view of FIG. An application has been proposed for a cast iron. In the figure, 15 is a valve, 16
17 indicates a valve seat, 17 indicates a cooling channel, and 18 indicates a stem guide.

With the above conventional method, the insulation effect and damage prevention are better than port liners made only of ceramic pipes. There was damage to the ceramic due to the difference in thermal expansion between the ceramic and the ceramic, and there were problems with the insulation. Another disadvantage was that the holding force against the cylinder head was weak due to the difference in thermal expansion and vibration.

The present invention was made to solve the above problems, and its gist is that the outer periphery of the ceramic tube 1 is covered with ceramic wool 2, and the inlet and outlet portions of the ceramic tube 1 are covered with a metal rope-like material. To provide an exhaust port liner for an internal combustion engine, which is covered with a buffer material 3 and loaded as an exhaust port core to prevent this metal from directly touching ceramic when casting a cylinder head 4. It is something to do.

Hereinafter, the present invention will be explained with reference to the partial cross-sectional view of FIG.

The outer periphery of the ceramic tube 1 is covered with ceramic wool 2, and the inlet and outlet portions of the ceramic tube 1 are fitted and covered with a cushioning material 3 made of press-molded metal rope. The cylinder head 4 is made of cast iron, and in the figure, 5 is a valve, 6 is a valve seat, 7 is a cooling channel, and 8 is a stem guide.

When such a ceramic tube is wrapped and cast, there is no direct contact with the cylinder head, which reduces the thermal shock caused by the difference in thermal expansion and the vibration of the engine during use, preventing damage and creating a heat insulating effect. At the same time, we were able to strengthen the holding force with the cylinder head and eliminate defects such as loosening.

The press-formed metal wire used for the inlet and outlet portions of the ceramic tube in the present invention is better as the wire size is smaller, and is press-formed by overlapping a desired number of metal wires. In addition, when the mesh size of the press-formed metal wire is large and the cast metal solution penetrates, good results can also be obtained by applying heat-resistant cement or heat-resistant mortar to the outer circumferential surface of the molded metal wire. The material of the metal wire used here is that if the molten casting is aluminum at 750℃,
Any metal rope that can withstand temperatures of 760℃ or higher is sufficient.
If the temperature of steel is 1400℃, you can use metal rope that can withstand higher temperatures.

Examples will be described in detail below.

The outer periphery of a ceramic port liner whose main component is aluminum titanate and has an inner diameter of 30φmm, a wall thickness of 1.5 tmm, and a length of 100 mm is covered with ceramic wool whose main component is alumina with a wall thickness of 3 mm and a length of 80 mm. , an inner diameter of 33φ, made by press-forming multiple layers of stainless steel wire with a wire diameter of 0.26φmm and a thread size of 0.3mm.
A buffer tube with a thickness of 3 mm and a length of 10 mm was inserted into the core, and aluminum molten at 750°C was cast on the outside. As a result, the damage to the ceramic was 10 mm.
Not one of them occurred.

This cast port liner was installed in an internal combustion engine and a rotation test was performed for 200 hours, but the tight fixation between the ceramic port liner and the aluminum exterior did not loosen in 10 out of 10 pieces, and the condition was the same as before the rotation test. It was hot. There was also no damage to the ceramic port liner.

On the other hand, the outer periphery of the ceramic tube 11 of the conventional example shown in FIG.
When covered with aluminum and cast in aluminum, 2 out of 10 cracks occurred, and when installed in an internal combustion engine and tested for 200 hours of rotation, 1 out of 8 cracked and 3 cracks occurred in the cylinder head. It became loose and rattled.

As described above, the exhaust port liner for an internal combustion engine of the present invention has an excellent structure that does not cause damage to metal castings or damage or loosening due to vibrations of the internal combustion engine.

[Brief explanation of the drawing]

FIG. 1 is a partial sectional view of the present invention, and FIG. 2 is a partial sectional view of the conventional example. 1...Ceramic tube, 2...Ceramic wool, 3...Buffer material using metal rope, 4...Cylinder head, 5...Valve, 6...Valve seat, 7...Cooling channel, 8...Stem guide.

Claims (1)

[Scope of utility model registration request] The outer periphery of the ceramic tube 1 is covered with ceramic wool 2, and the inlet and outlet portions of the ceramic tube 1 are covered with a metal rope-shaped buffer material 3, which is loaded as an exhaust port core and installed in the cylinder head. An exhaust port liner for an internal combustion engine, characterized in that the metal does not come into direct contact with the ceramic during casting.