Combustion chamber structure for diesel engine
AssigneeNissan Motor Co., Ltd.
InventorsIsshou Uehara, Manabu Hasegawa, Naohide Tsuji
Life of this patent
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Abstract
A direct injection diesel engine includes a piston having a reentrant cavity and a multi-hole fuel injection nozzle disposed on a center line of the cavity. The cavity is formed by a lip portion defining a smallest diameter at a position below a piston crown surface and a raised portion formed at a center of the bottom and shaped like a frustum of a cone. A conical surface of the raised portion is formed to have an angle pointing to a spray point of the fuel injection nozzle at a piston top dead center position. The height position of a top surface is substantially equal to the height position of the lip portion. This structure is to promote the oxidation of soot by utilizing the air in the central part of the cavity.
Claims4
A combustion chamber structure in a diesel engine including a piston having a crown surface formed with a reentrant cavity, and a multi-hole fuel injection nozzle disposed on a center line of the cavity, wherein
- a lip portion defining a minimum diameter in an entrance portion of the cavity is located below an opening brim,
- a spray center axial line extending from a spray point of the fuel injection nozzle is oriented to point to a position slightly below the lip portion at a position at or near a top dead center,
- a height position of a top of a raised portion formed centrally in a bottom of the cavity is set substantially equal to a height position of the lip portion, and
- a conical surface of the raised portion is formed at one of an angle pointing to the spray point of the fuel injection nozzle at a piston position at the top dead center, and an angle steeper than the angle pointing to the spray point, to form a region where an excess air rate is highest, on a center line of the raised portion.
Dependencies are inferred from the claim text.