Marine diesel engine

Abstract

Provided is a marine diesel engine capable of achieving stable combustion at critical speed so that the engine body can operate under better conditions. The marine diesel engine has: an engine body, exhaust valves of which are opened and closed so as to control discharge of air in combustion chambers; and a control device which controls the engine body and controls the operations of the exhaust valves on the basis of an exhaust valve closing timing pattern in which the timing for closing the exhaust valves during a combustion cycle is delayed as the rotation speed of the engine body increases.In the barred range, which encompasses the period during which the rotation speed of the engine body passes critical speed, and a first range in which the rotation speed is lower than in the barred range, the exhaust valve closing timing pattern has an inflection point at which the rate of change in the exhaust valve closing timing relative to rotation speed increase changes. The change rate on the barred range side of the inflection point is smaller than the change rate on the first range side of the inflection point.

Description

technical field [0001] The invention relates to a marine diesel engine. Background technique [0002] The marine diesel engine increases the rotational speed when starting to operate. Since the engine is a rotating machine, there is a critical speed range (Barred Range / barred range, critical speed / critical speed) in which resonance or the like occurs and long-term operation in this speed range is prohibited. Patent Document 1 describes adjusting the angle of injecting fuel and opening the angle of an exhaust valve for exhausting air combusted in a combustion region when the engine speed reaches a critical speed range. Specifically, it is described that the exhaust angle in the critical speed range is made smaller than the exhaust angle in a region lower than the critical speed range. [0003] prior art literature [0004] patent documents [0005] Patent Document 1: Japanese Utility Model Registration No. 3174346 [0006] In addition, in marine diesel engines, in order ...

AI Technical Summary

Problems solved by technology

In this way, when the control to increase the rotational speed of the engine is executed, the balance of fuel and air in the engine is disrupted, the combustion of the fuel becomes insufficient, and there is a possibility that the speed of increase of the rotational speed may decrease or black smoke may be generated.

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