Design & Development of Partial Engine Encapsulation for Interior Noise Reduction in Commercial Vehicles

This paper focuses on partial encapsulation technique for reducing air-borne noise from the rocker cover of a commercial vehicle diesel engine. Due to increasing awareness, customers demand for improvised NVH (Noise Vibration and Harshness) performance in modern day vehicles. Better NVH performance implies better comfort for passengers as well as vehicle operator. This further increases the driver up time due to reduced driver fatigue. In order to improve NVH performance of existing vehicle and observe different noise and vibration zones, detailed noise and vibration mapping was carried out on one of our vehicle platform. It is observed that engine noise is one of the major contributors for interior noise, apart from road inputs etc. There are well established methods to reduce the inherent noise of the engine, but the same might affect other performance parameters including fuel efficiency and exhaust emissions, which are pain areas of major automotive industries due to stringent homologation norms. Engine top area partial encapsulation with barrier cover is designed considering various integration as well as heat load constraints at vehicle level. The designed barrier cover was developed as per retrofit able feature which also improves engine aesthetic. NVH performance trials were carried out with and without this developed prototype and compared the results to observe effectiveness of this noise barrier. It has been observed that using partial encapsulation 4-5% decrease in interior noise levels can be achieved. This paper also includes the challenges involved in designing and developing the part as per customer convenience without affecting engine performance and provide better ride comfort