Reduction of Engine Induced Vibrations in a 150 cc Scooter 2001-26-0038
Ride discomfort due to engine induced vibrations has always been an important issue of concern in two wheelers. This paper discusses the efforts taken to reduce the transmission of engine induced vibrations to the chassis and thereby improving ride comfort of a 150 cc, two stroke scooter.
At the start of this exercise, the vibration measurement methodology was established to achieve high accuracy and repeatability. Correlation between subjective test results on road and objective test results in the laboratory was also established.
Subsequently, scatter of vibration levels in mass production was quantified. Detailed evaluation of these mass production vehicles and a study of various parameters helped to identify the most sensitive parameter contributing to the production variation. The parameter “Assembled Radial Stiffness (ARS)” of the big end engine mount showed maximum impact on vibration levels. Different parameters causing variation of ARS, despite engine mounts and crankcase being as per design were studied. A simple test procedure was devised to check this parameter on production line, to reduce production variation. Further, detailed study of the engine mounts and subsequent modifications in the mounts enabled to reduce overall vibration levels.