PURPOSE: To prevent the turbulence chamber insert from being cracked by a method wherein a metallic ring is shrink-fitted on the outer periphery of the turbulence chamber insert body made of ceramics on condition that a necessary compressive stress remains and pressed into a cylinder head.
CONSTITUTION: The turbulence chamber insert 20 is composed of a main body 21 made of ceramics with silicon nitride as the subject and the metallic ring 22 fitted on the outer periphery of the main body 21. The ring 22 is shrink-fitted on the outer periphery of the bottom wall 21a of the body 21 on condition that a necessary compressive stress remains in the body 21 even when said engine is operated. The shrink-fit is conducted at 400W800°C of shrinking temperature and 100W250μ of shrinking allowance. For example, if the outer diameter of the main body 21 is 34mm at normal temperature, the ring 22 for its inner diameter is made (34mm- 150μ) at normal temperature and the ring 22 alone is warmed at 500°C to be fitted. In such a manner, the necessary tensile stress remains in the ring 22 and acts as compressive force upon the main body 21 even in the operation of the engine. Accordingly, it is suppressed that the main body 21 at its bottom wall 21a is cracked.
SEKO HIDEO
ISHIZAWA KENKI
HAISHI HIDEKI
SHINAGAWA REFRACTORIES CO
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