Design Method of Number of Teeth for Low Noise Gears Considering Human Aural Characteristics

Abstract

Recently, increased user demand for quiet vehicle environments has resulted in the need to develop low-noise gears that do not generate noises that are harsh on to the human aural. The principal method for reducing meshing transmission error has been to gear design with as many teeth as possible. However, while these design methods have focused on decreasing gear noise, they have not considered the relationship between gear noise and the background noise of vehicle interiors. In fact, it would appear that no research considering the human aural characteristics associated with gear noise under these conditions has been conducted to date. Furthermore, the problem of gear noise on background noise in vehicle has increased as the use of hybrid engine technology in vehicle has become more pervasive in recent years. The proposed technique for reducing gear noise involves gear design that frequency control of gear noise by changing the number of teeth. The technique described here considers human aural limit and the influence of masking, and how these are affected by the tooth settings of low noise gear. This was achieved by assessing human aural characteristics in the unique acoustic environment of the vehicle interior. Then, the relationship between the number of teeth and the sound pressure level of gear noises was investigated. It was found that the proposed method of varying the number of teeth was effective for designing gears with optimal human aural characteristics.