Abstract
Torsional vibration occurs at a crankshaft system of operating multi-cylinder reciprocating engine in mechanism. A torsional vibration rubber damper is generally used to control or reduce the torsional vibration appearing at the crankshaft system of small diesel engine for automobile. Since automotive diesel engines have recently become engine weight lightening and higher performance output, both the amplitudes and the frequencies of the torsional vibrations generate increasingly more than before. Therefore, the torsional rubber damper should be required as one of the most important engine vibration reduction devices. The torsional vibration rubber damper must be precisely designed to match with a crankshaft system of engine with which it is mounted in order to reduce sufficiently. However, the prediction difficulty of its dynamic characteristics gives damper designers the design of a torsional rubber damper with variable experiments. While this design method requires too much time for examination of the vibration reduction effects obtained from some torsional oscillation tests, it is doubt whether the designed torsional damper will be able to sufficiently reduce the torsional vibration in variable engine operations. This paper refers to influences of rubber shape and forced frequency on properties of test rubber specimens designed for contribution to damper design.
Furthermore, some important subjects on properties of rubber are described for design of shear-type torsional rubber dampers by using a rheological model. The rubber properties can be obtained from exciting vibration tests of rubber specimens with the changes of exciting frequency, amplitude and temperature. It is confirmed that the shape factor should be reduced to suppress the influence on rubber dynamic properties of external factors such as amplitude and frequency.
