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In this study, the genetic algorithm so called GA is newly applied for the optimization of many engine mounting parameters, calculations of stiffness matrix and inverse matrix to obtain 6 degrees of freedoms displacements at mounting points and a center of gravity. As a result, the optimized result could be shortly obtained in a minute, and an inexperienced engineer could easily make the optimum engine mounting layout, which can satisfy the vibration isolation and the non-interference in an engine compartment.

This study has been conducted aiming at reductions of piston slap noise and piston friction loss, and effects of lubricating oil supply between the piston skirt and cylinder on diesel engine have been verified through a series of experiments. Namely, lubricating oil was supplied forcibly into the piston skirt from outside of engine, and its effects on the cylinder block vibration, piston friction force, slap motion and oil consumption have been measured. As a result, it has been verified that the supply of a small amount of oil (6mL/min) to the piston skirt reduces about 50 % of the block vibration caused by the piston slap motion in idling operation, and about 20 % of the piston friction loss in full load operation. Furthermore it has verified without giving any significant adverse effect on oil consumption.

First of all, we would like to introduce the basic engine mounting layout analysis by the equation of motion and the FEM simulation. For the heavy-duty vehicle, the 4 supporting points engine mounting is basic, but the other types, such as 3 and 5 points also exist. So, we researched what is the best layout to isolate the vibration and support the engine dynamic torque among 11 layout systems by the analyses of eigen value, the frequency response, and the transient response. According to these above studies, when considering all the various criteria, the best engine mounting is the sloping layout. It is the 3rd best for the reduction of engine idling vibration and is the 2nd best against the shock torque.

Piston slap impact noise has been investigated using a piston secondary motion simulation. This simple model accurately estimates piston slap impact, by considering the hydrodynamic effects of the piston skirt oil film and the friction forces at various contact points. The results were compared with the actual piston motion measured by a link mechanism. Consequently, the calculation accuracy was confirmed to be sufficient to make precise estimates of piston slap noise.

This paper reports a numerical simulation method for suppressing abnormal vibration on the cab caused by torsional vibration on the powertrain, using a mechanical dynamics analysis software. The simulation model for the numerical analysis is adopted to the powertrain. Seven design parameters were selected and optimized to minimize the acceleration of the vibration by using Design of Experiment (DOE). Validation tests were conducted on the optimized model, and a good agreement was achieved between the test results and the calculated ones. This new design has helped us a lot to save weight, cost and time by narrowing down design change proposals.

A new series of 6 cylinder direct injection 8.4 liter diesel engines have been designed by Isuzu Motors Limited. Naturally aspirated, turbocharged and turbocharged-aftercooled versions, have been developed to meet the needs of 8 to 16 ton GVW commercial vehicles, as well as industrial and marine applications. These engines cover the range of 147 - 200 kw (195 - 270HP) output. The design objectives for these engines included such features as high output, better fuel economy, high reliability and durability, as well as minimum weight and cost. This paper deals with the design, development and performance aspects of these engines.