Mazda Motor Corporation

Makoto Namba

Daisuke Shimo

Sangkyu Kim

Masahiro Miyazaki

Yudai Kato

Shuji Takuma

Kazunori Hirabayashi

Tadashi Tadokoro

A structure of a combustion chamber is provided. The structure includes a cavity formed in a central part of a crown surface of a piston and a wall surface constituting the cavity. The wall surface has a central ridge portion bulging farther toward a bottom surface of a cylinder head toward a center of the cavity, a periphery concave portion formed radially outward of the central ridge portion to concave radially outward, and a lip portion formed between the periphery concave portion and an opening edge of the cavity to convex radially inward. An outer circumferential part of the crown surface has a first portion and a second portion located radially outward of the first portion. A stepped portion is formed between the first and second portions. A stepped portion volume ratio of a stepped portion volume to a top dead center volume is set to 0.1 or smaller.

Combustion chamber structure for diesel engine

A diesel engine includes a piston, a cylinder head, and a fuel injector. The fuel injector has a valve body with bored nozzle holes in its tip part. A cavity having a circular shape in plan view is formed in a crown surface of the piston to concave to the counter cylinder head side. A wall surface constituting the cavity has a central ridge portion bulging toward the fuel injector while bulging larger toward the center of the cavity, a periphery concave portion formed radially outward of the central ridge portion to concave radially outward, and a lip portion formed between the periphery concave portion and the crown surface to convex radially inward. A lip radius R, a nozzle hole length L, a nozzle hole diameter D, and a bore radius B are designed to satisfy the following equation:99.4&#xd7;(1&#x2212;3)&#xd7;(+2.7)&#x2266;&#x2266;min{237.1&#xd7;(1&#x2212;3)&#xd7;(0.8+1),2/3}.

Diesel engine

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Kure, Japan

Makoto Namba