Noise control and experimental study of a highpressure oil pump enclosure

Abstract

The present experimental study has been conducted to evaluate the impact of an acoustic enclosure of high-pressure oil pump, which is used to reduce the noise emission of an automobile engine. The enclosure is double-layered and made of nylon 66 (PA66) as an outer structure and polyurethane foam as the inner material. The sound signals of the engine were measured separately without an acoustic enclosure and covered by the enclosure. The signals were measured with 5 microphones around the engine under two electric loading conditions (0% and 100% load). The results revealed that the sound pressure level (SPL) of the engine increased significantly with the high-pressure oil pump installed, and the gap between SPL was larger for 100% load than 0% load. Furthermore, the enclosure of high-pressure oil pump was effective to attenuate the engine noise at almost the entire audio frequency range. The SPL reduced approximately 2 dB within nearly the entire test frequency range, supporting the remarkable noise reduction effect of the high-pressure oil pump enclosure.