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The torsional vibration of diesel engines has become severer with the increase of exciting force by higher pressure. Therefore, the running crankshaft is highly stressed owing to the large torsional vibration. Then, torsional viscous fluid dampers of high performance have been employed in high mean effective pressure diesel engines as a measure for vibration reduction. As the dynamic characteristics of the dampers have such a great influence on the vibration of the engine crankshaft system that they cannot be ignored, the viscosity of the silicone oil and the peripheral and lateral gaps of the dampers are diversely varied in the experiment. As the equipment for the measurement of torsional vibration displacement, a phase-shaft type torsiograph equipment was adopted so as to make it easy to measure simultaneously angular displacements of the casing and the inertia ring.

This is the study on the vibration characteristics of the fuel-injection pump body. Recently, refinement of the fuel spray is necessary in order to reduce the toxic substance, which is included in automotive exhaust gas of diesel engine for the automobile. To jet diesel fuel in higher pressure is a method for spraying the fuel more minute into a cylinder. However, this method causes the increase in respect of engine vibration and torque nonuniformity. The fuel-injection pump body receives not only this engine vibration by the method but also impact tute by the high-pressure injection. As this result, the sufficient performance cannot be demonstrated because large vibration deformations occur at the body and the camshaft of the fuel-injection pump. The vibration characteristics of the fuel-injection pump, which can reduce these vibration deformations, are necessary in order to lead to the performance.

Three types of cylinder head gaskets which were different in their structures and materials, were adopted for experimental study to describe cylinder head motions due to thermal cycle conditions. The experimental studies were conducted by measuring (1) the temperatures on the cylinder head gasket, the cylinder head, the cylinder block and head bolts,(2) the relative displacements of the cylinder head and block, (3) the axial tensions on the cylinder head bolts, and (4) the indicator diagram, on the engine testing with a specific thermal cycle. Following conclusions were obtained as the results; The effect of the change in circulating water temperature on the sealing function of cylinder head gaskets has become clear through this experimental study. The mutual relationship between the deflection of the cylinder head and the temperature at the gasket and its peripheral region, has been able to estimate sufficiently from the results of the measurement.

The production unit number of small diesel engine cars tends to decline except recreational vehicles in Japanese market in recent years, while the production unit number in Europe market keeps on increasing owing to the merits of the durability and the fuel consumption. The small diesel engines will have to be improved in the near future by solving major problems such as noise and vibration pollution, environmental pollution, improvement in performance of diesel engines, in order to expand the production of the engines. This paper refers to a basic study on the experimental and analytical methods for the reduction of resonant vibration in each vibration mode on some cylinder blocks of small high-speed diesel engines in rated engine speed range. Hammering test method, which is easy and useful for measuring frequency response functions, is carried out in the experiments.

The unknown characteristics of the bending vibration coupled with torsional vibration (hereafter called“coupled torsional, bending vibration”) are investigated from the experimental and analytical viewpoints. The torsional and bending vibration stresses of the crankshafts of a 6 cylinder, in - line engine and an 8 cylinder, V - type engine are measured first in order to investigate experimentally the characteristics of the coupled torsional - bending vibrations. Next, the displacements, moments and stresses of the torsional and bending vibrations of the above - mentioned crankshaft are calculated by 3 dimensional, forced vibration analysis of the crankshafting of the V 8 engine using the transfer matrix method, which has been developed by the authors. Finally, the experimental results are compared with the corresponding calculated results and the characteristics of the bending vibration stresses coupled with the large torsional vibrations are made clear.