JPH10231752A - Intake/exhaust port for internal combustion engine cylinder head - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce resistance when intake/exhaust flows in an intake/exhaust port, and improve an intake/exhaust efficiency by coating heat resistance coating on an inner wall surface of the intake/exhaust port for improving its surface roughness, in the intake/exhaust port arranged in a cast made cylinder head by means of core casting. SOLUTION: In a cast made cylinder head 1, its lower surface is formed as a combustion chamber 2, and an intake (or exhaust) port 4 which is communicated with the combustion chamber 2 bending from an opening part 3 arranged on the side surface of the cylinder head 1 is arranged by means of core casting. In this case, heat resistance coating 6 is coated from the opening part 3 of the intake port 4 along over all surfaces of an inner wall surface 4b led to a fitting part of a valve seat 7. For example, pyroputty of ceramic compound and the like are used as the heat resistance coating 6. Therefore, the resistance of the inner wall surface 4b is reduced so as to make flow of intake smooth, an intake efficiency is improved, and the performance or the profitability of an internal combustion engine is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an intake / exhaust port which is provided in a cast cylinder head of an internal combustion engine by casting and communicates the outside of the cylinder head with the inside of the cylinder.

[0002]

2. Description of the Related Art Conventionally, the inner wall surfaces of an intake port and an exhaust port of a cast cylinder head of an internal combustion engine have been used as cast, and shot blasting is used to improve the surface roughness. Alternatively, polishing with a tool such as a grinder is performed. Improving the surface roughness of the inner wall surface of the intake port and the exhaust port smoothes the flow of the intake or exhaust gas, reduces the resistance, and improves the intake / exhaust efficiency, thereby improving the output performance or economy of the internal combustion engine. Important for. However, the above method for improving the surface roughness not only requires man-hours and costs, but also the port shape slightly affects the combustion efficiency and the intake / exhaust efficiency. I have a problem.

[0003]

SUMMARY OF THE INVENTION Accordingly, the present invention aims at improving the performance or economy of the internal combustion engine by smoothing the flow in the intake / exhaust port, reducing the resistance, and improving the intake / exhaust efficiency. It is an object of the present invention to propose an intake / exhaust port for a cast cylinder head of an internal combustion engine which is easy to manufacture.

[0004]

According to the present invention, there is provided in a cast cylinder head of an internal combustion engine by blanking,
In an intake / exhaust port communicating between the outside of the cylinder head and the inside of the cylinder, a heat-resistant paint for improving the surface roughness is applied to the inner wall surface of the intake / exhaust port.

The present invention is constructed as described above. A heat-resistant paint is applied to the inner wall surface of the intake / exhaust port to improve its surface roughness, and the intake or exhaust flowing through the intake / exhaust port flows smoothly. The resistance is reduced, and the intake and exhaust efficiency is improved.
And since it is a heat resistant paint, it can withstand the temperature of the exhaust gas and prevent the adhesion of carbon, and its performance is maintained.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. In FIG. 1, a combustion chamber 2 is formed on a lower surface of a cast cylinder head 1 by a cylinder (not shown) provided in a cylinder block and a piston (not shown) sliding in the cylinder. An intake (or exhaust) port 4 which is curved and communicates with the combustion chamber 2 is provided by casting from an opening 3 provided on a side surface of the cylinder head 1. A valve seat 7 is provided at a portion where the intake (exhaust) port 4 communicates with the combustion chamber 2, and a mushroom valve 5 for opening and closing the intake (exhaust) port 4 and the combustion chamber 2 is mounted. The shaft portion 5a of the mushroom valve 5 penetrates the bent portion 4a of the port 4 and is urged and held by a spring (not shown) provided above the cylinder head 1.

A heat resistant paint 6 is applied to the entire inner wall surface 4b from the opening 3 of the intake (exhaust) port 4 to the fitting portion of the valve seat 7. As the heat-resistant paint 6, for example, a ceramic compound Pyropate manufactured by Alemco Products of the United States may be used.

In the above, the intake port has been described.
The same applies to the exhaust port. The application of the heat-resistant paint 6 may be performed on both the intake port and the exhaust port, or any one of them.

In the above-described embodiment, the inner wall surface 4b of the intake / exhaust port 4 has a rough surface as cast, as shown in FIG. 2, and the flow A of the gas flowing through the port 4 is as shown in FIG. In particular, it is disturbed near the wall and has high resistance. By applying the heat-resistant paint 6, the surface roughness is improved as shown in FIG. 3, the gas flow B becomes smooth, and the resistance decreases. As a result, the intake and exhaust efficiency is improved, and the performance of the internal combustion engine is improved. The heat-resistant paint is, for example, a heat-resistant temperature of 10 for the ceramic compound of the pyropate.
Since the temperature is not less than 00 ° C., it can withstand the temperature of the exhaust gas and the adhesion of carbon is prevented, so that its performance is maintained.

In addition, the intake port has a role of forming an appropriate swirl in the combustion chamber not only as an intake passage but also for controlling output performance or exhaust gas characteristics. It is set to a complicated shape. Therefore, adding machining to improve the surface roughness is, for example, in a manual operation with a grinder, etc.
There is a problem from the viewpoint of quality maintenance. From such a point, in the present invention, the port is cast with a precisely manufactured core mold, and the port is painted, so that there is no need for machining such as machining, and there is no variation in quality.

[0011]

As described above, the present invention is constructed as described above. (1) By improving the surface roughness of the inner wall surface of the intake / exhaust port, the flow of the intake air or the exhaust gas becomes smooth, and the resistance is reduced. Since the intake / exhaust efficiency is improved, the performance or economy of the internal combustion engine can be improved. (2) Carbon is prevented from adhering to the port,
Performance degradation is prevented. (3) Rust in the port and cast sand falling off can be prevented. (4) Since the port is cast with a precisely manufactured mold and the port is coated, manufacturing is easy, and there is no variation in quality due to processing.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an embodiment of the present invention.

FIG. 2 is an explanatory view of a conventional port inner wall surface and a flow state.

FIG. 3 is an explanatory diagram of a port inner wall surface and a flow state according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Cylinder head 2 ... Combustion chamber 3 ... Opening 4 ... Port 4b ... Inner wall surface 5 ... Mushroom valve 6 ... Heat resistant paint 7 ... Valve seat

Claims (1)

[Claims] 1. An intake / exhaust port provided by casting in a cast cylinder head of an internal combustion engine and communicating the outside of the cylinder head with the inside of the cylinder to improve the surface roughness of the inner wall surface of the intake / exhaust port. The air intake / exhaust port of the cylinder head of an internal combustion engine, which is coated with a heat-resistant paint.