It is likely that the demands for marine diesel engines from the shipbuilding and the shipping industries go toward the synthetic economy by improving reliability and increasing added functions rather than the reduction in fuel consumption. In such circumstances, the authors have been engaging in the development of the engines with high flexibility and reliability which can meet the demands of clients by applying electronic control technique to each component of the engines and by constructing them as a system. This paper will explain the whole conception of the above-mentioned system and introduce the AFR (Aut-omatic Flexible Rating) and the ALL (Automatic Cylinder liner Lubricating) control systems which has already been developed at the present.
This paper describes the influence of the correction factors on the engine NOx discharge level as well as the NOx data fluctuation for engines with 165 mm-to-320 mm in bore. The weighting coefficients of the correction factors are derived for leveling NOx data by means of the least-squares-method based on the calculation step assuming that NOx level is primarily a function of absolute humidity, cylinder inlet air temperature, and diesel engine fuel oil specific gravity instead of the cetane index having a good correlation with the ignition quality. Effects of the correction coefficients are explained in terms of the leveling of NOx data and the prediction of NOx discharge from the stationary diesel engine. The results indicate that NOx emission increases with a decrease in absolute humidity, the increase of the cylinder inlet air temperature and the specific gravity of the diesel fuel oil. Additionally, a chart for estimating the effect of the NOx correction factors and predicting the NOx emissions is introduced.
The theme of this research is to develop new diagnostic system of marine diesel engine by acoustic sound in order to substitute for the crew's diagnosis. This paper discusses the experiment of diagnosing the gas leakage from the exhaust valve of the fourstroke engine in a training ship, Yuge-maru, in motion. The original acoustic sound from the engine is analysed through (1) power spectrum analysis, (2) filtering analysis, (3) enveloping analysis, (4) ‘partial extraction' analysis, and then displayed in a colored pattern. In the colored pattern, one may easily read that, in the frequency range higher than 6.3 kHz, the power levels at both times of opening and closing the exhaust valve become lower as the size of the slit on the exhaust valve is incressed. Therefore the crew can easily find a fault of the engine at a glance.
For the purpose of making clear the influence of some ingredients of marine degraded fuel oil on machinery failures, samples of fuel oil taken from many ocean going ship's and used with main and auxiliary propulsion machinery and presumed to have been the cause of failure, were investigated by multivariate analysis. It was found that the occurrence of failures of pre-treatment systems by degraded fuel oil is influenced by five factors : mesh size of strainer, high viscosity, high water content, asphaltenes, and aluminium. And it was also found that degraded fuel oil can be roughly discriminated by specific, gravity, viscosity, carbon residue, sulphur, wather, ash, asphaltenes, which may cause failure on the main engine or pre-treatment system. Also, it was found that higher specific gravity and content of vanadium and aluminium affects the occrrence of such failure of main engine as sticking, abrasion, abnormal combustion, difficulty of combustion; the condition of high water and sodium content affect such failure of main engine as stains and obstacles after combustion.