Search Results

The separation of combustion noise and mechanical noise from the total noise of a four-cylinder in-line diesel engine at idling was carried out with high accuracy by changing the fuel injection timing. The mechanical noise, which accounts for the major share at 93%, was then separated into noises from the typical mechanical causes, and the valve train was found to be the major noise source. From analysis of the noise generating mechanism for the valve train, it was clarified that the noise was caused mainly by the gear rattling owing to the variation in the camshaft drive torque.

This paper describes an attempt to clarify the characteristics of combustion noise generation of the engine structure. The transmission-radiation coefficient of combustion noise is proposed as a conversion ratio of the combustion noise power from the gas vibration power affecting the inner surface of the combustion chamber These experiments were carried out both with a stationary engine excited by a single explosion and an operating engine. From these results, the frequency characteristics of the combustion noise generated by each engine wall and the vibration response of each transmission path are discussed.

In the present work, an attempt was made to predict engine noise from the shape of the burning rate curve. Thus, the influence of the shape of the burning rate curve on engine noise, especially on combustion noise was studied in detail and clarification of the relationship was successfully made. At first, an approximation of burning rate curve using a function was attempted. And in second, the transfer rate from cylinder pressure to combustion noise was obtained. Then, the relation between the deciding parameters of burning rate curve and noise and performance of engine were studied.