Diesel engine

Abstract

A diesel engine (1) configured so that fuel spray patterns (45, 46) are formed in a combustion chamber (15), in which the swirl flow (W) of intake air is being generated, by directly injecting the fuel from a fuel injection nozzle (4) having a multiple nozzle hole structure. The diesel engine (1) is provided with a superposition avoidance structure for reducing the superposition of the fuel spray patterns (45, 46) emitted from adjacent nozzle holes (34a, 35a). A valve timing mechanism (17) is provided as the superposition avoidance structure, and the valve timing mechanism (17) sets the timing (29a, 50a, 51a), which is the start point of the valve closing operation of air intake valves (3c, 3c) for sucking air into the combustion chamber (15), to a point before the bottom dead center (B) of air intake. Also, the valve closing operation is provided with a buffering section (52) in which the seating speed of the air intake valves (3c, 3c) is reduced to buffer the impact of the seating, and the timing (51c) which is the start point of the buffer section (52) is set to a point before the bottom dead center (B) of air intake.

Description

technical field [0001] The present invention relates to a direct-injection type in which fuel is directly injected into the combustion chamber from a fuel injection nozzle having a multi-jet structure by causing the air sucked into the combustion chamber to rotate horizontally to generate a swirling swirling flow (hereinafter referred to as "vortex"). Diesel engines, in particular, relate to combustion technologies capable of reducing NOx without incurring deterioration of fuel consumption and increase in the amount of black smoke. Background technique [0002] Conventionally, in a direct-injection diesel engine that injects fuel directly into a combustion chamber to perform self-ignition, timing retardation is known as a technique for reducing the amount of NOx produced. This so-called timing delay is a technique to reduce the maximum combustion temperature by delaying the ignition time, and suppress the reaction of nitrogen and oxygen to reduce the amount of NOx produced. ...

AI Technical Summary

Problems solved by technology

This so-called timing delay is a technique for reducing the maximum combustion temperature by delaying the ignition time, and suppressing the reaction of nitrogen and oxygen to reduce the amount of NOx produced. However, at this time, due to the fuel supplied after the initial combustion that reaches the maximum combustion temperature Therefore, the combustion becomes incomplete, the fuel consumption is poor, and the amount of black smoke is also large.

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