Jouji Kimura

Crankshaft Torsional Vibration Characteristics in a Vee-Type Six-Cylinder Diesel Engine

Engines have been designed to avoid low-harmonic-order resonant torsional vibration in a commonly-used engine speed range, but the authors have found that, in some engines, especially turbo-charged engines, a significant degree of a low-harmonic-order exciting torque acts on the crankshaft. In these engines, the amplitude of non-resonant low-harmonic-order torsional vibration is almost as large as that of the resonant one and the amplitude of non-resonant vibration can not be controlled by a damper. Accordingly, to investigate the characteristics of non-resonant low-harmonic-order torsional vibration is important. This paper describes the characteristics of non-resonant and resonant torsional vibration for a vee-type six-cylinder diesel engine.Copyright

Generating Mechanism of Oilpan Moan Noises of Diesel Engines

The noise of diesel engines operating at low idle is an important noise evaluation criterion in both commercial vehicles and passenger cars. At low idle, a quiet, pleasant noise is required. Therefore, any unusual noises that occur at low idle represent a serious problem, and the noises must be prevented. This paper presents the characteristics of the moan noise, which is an unusual noise that radiates from the oilpan at low idle, and the mechanism by which the moan noises are generated in a diesel engine. In addition, a means of preventing the moan noises is discussed.Copyright

Analysis for Strain on Torsional Damper Rubber and Torsional Vibration on Crankshaft for a Diesel Engine

A torsional damper is attached to a crankshaft pulley to control torsional vibration. Torsional strain is produced on the rubber when it is placed between the damper plate and the damper ring. The authors know from our experience that, in some engines, especially in turbo-charged engines, such a significant degree of strain is produced on the damper rubber at a resonant engine speed that the rubber is torn off in two pieces. This paper presents a method of estimating strain caused by torsional vibrations and discusses the relationship between the crankshaft torsional vibration and the strain.Copyright