REDUCING VIBRATION OF A 2-CYLINDER OUTBOARD MOTOR BY THE PENDULUM MOTION MOUNT METHOD

In order to reduce the vibration of the 4-stroke 2-cylinder outboard motor, the vibration of the outboard motor was analyzed theoretically. By using a 2 dimensional kinetic model, the equation of motion was obtained. Vibration acceleration at handle and the excitation forces to the hull were described by solving these equations. Through this analysis, the theory of isolating vibration by the pendulum motion mount method is established by finding the design condition which isolates vibration effectively. The method was applied to the design of the outboard motor. The mount location was optimized to minimize vibration, and the mount structure was designed for endurance. The body of the outboard motor was designed to optimize its vibratory characteristics in order to avoid resonance. Experimental verification of the newly developed 4-stroke 2-cylinder small outboard motor revealed that the effectiveness of vibration reduction was equal to, or better than, that of the outboard motor equipped with a 1st order balancer.