Mount Force Reduction in a Scooter Engine Mounting System

Crank balance factor and phase of crank balance tuning to minimize an engine mount forces by experimental methods during vehicle development is a time consuming process. The degree of crank balance factor and phase of crank balance optimization achieved relying on this approach alone is highly dependent upon the development engineer's experience. This situation should be helped if the initial crank balance factor and phase of crank balance provided to the development activity is near optimum. Engine mount forces are very crucial as they are primarily responsible for vibration of the vehicle. This paper discusses a method of modeling a scooter engine mounting system to predict mount forces and to minimize the mount forces by optimizing the crank balance factor and phase of crank balance. The engine mounting system under study is for a single link toggle mechanism used for scooter engines. A planar multi-body dynamics approach is used to model the system considering engine excitation forces, suspension and tire forces. Using an embedding technique, the governing equations are reduced to the independent acceleration equations and solved using a 4th order Runge-Kutta method for the independent co-ordinates and velocities. The dependent accelerations and mount forces are then obtained. The simulated acceleration results are used to validate the model which is compared with experimentally measured data. An optimization algorithm is then developed to minimize the mount forces that are transmitted to the vehicle frame by optimizing crank balance factor and phase of crank balance.