First-order vibration, which an engine generates, has been isolated by applying the pendulum motion mount method to a 4-stroke 2-cylinder outboard motor. First, the vibration of the outboard motor was theoretically analyzed using a two-dimensional kinetic model. Through this analysis, the theory of isolating vibration using the pendulum motion mount method was established by finding the conditions which isolate vibration effectively. Next, this method was applied to the design of an outboard motor. The mount location was optimized in consideration of both the function and the vibration, and the mount structure was designed in consideration of endurance. The body of the outboard motor was designed by optimizing the vibratory characteristics in order to avoid the resonance. The experimental verification using 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 an outboard motor equipped with a first-order balancer.
Article of Honda R&D Technical Review Vol.12 No.2 (119 - 126)