Air-cooling type internal combustion engine and saddled vehicle having the same

Abstract

The present invention relates to an air-cooling type internal combustion engine and a saddled vehicle having the same. The air-cooling type internal combustion engine includes a cylinder head body (100), the cylinder head body (100) including: a plurality of cooling fins (10); a cam chamber wall (20) defining a cam chamber (109); a combustion chamber wall (30) defining a combustion chamber (110); an intake duct (40) through which air intake into the combustion chamber (110) is to occur; an exhaust duct (50) through which exhaust from the combustion chamber (110) is to occur; and a cooling air duct (60) for allowing cooling air to pass through the cam chamber wall (20) and the combustion chamber wall (30). The cylinder head body (100) is integrally molded from an aluminum alloy by die casting. The cylinder head body (100) further includes a cam chain chamber (70) for accommodating a cam chain (113). When viewed in the cylinder axis direction (D1), the exhaust duct (50) extends in such a manner that the exhaust duct (50) becomes more distant from the cam chain chamber (70) when going from the inlet side toward the outlet side, and the exhaust duct (50) is formed so that an axis (50x) of the exhaust duct (50) is linear.

Description

technical field [0001] The present invention relates to internal combustion engines, and more particularly to air-cooled internal combustion engines. Furthermore, the present invention also relates to a saddled vehicle including an air-cooled internal combustion engine. Background technique [0002] In recent years, there has been an increasing desire to operate internal combustion engines at higher compression ratios in order to improve fuel efficiency. However, when the compression ratio is increased, the temperature near the top dead center of the piston tends to rise, and knocking tends to occur. [0003] In order to prevent such knocking, it is necessary to improve the cooling performance of the cylinder head. In general, an air-cooled internal combustion engine tends to have lower cooling performance than a water-cooled internal combustion engine. Therefore, especially in an air-cooled internal combustion engine, further improvement in cooling performance of the cyli...

AI Technical Summary

Problems solved by technology

However, when the compression ratio is increased, the temperature near the top dead center of the piston tends to rise, and knocking tends to occur

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