Engine mount design technique to address vehicle level Buzz, Squeak & Rattle

Abstract

In the highly competitive global automotive market and with the taste of customer becoming more refined, the need to develop high quality products and achieve product excellence in all areas to obtain market leadership is critical. Buzz, squeak and rattle (BSR) is the automotive industry term for the audible engineering challenges faced by all vehicle and component engineers. Minimizing BSR is of paramount importance when designing vehicle components and whole vehicle assemblies. Focus on BSR issues for an automobile interior component design have rapidly increased due to customer's expectation for high quality vehicles. Also, due to advances in the reduction of vehicle interior and exterior noise, engine mounts have recently been brought to the forefront to meet the vehicle interior sound level targets. Engine mounts serve two principal functions in a vehicle, vibration isolation and engine support. The objective of this paper to experimentally analyze the impact of conventional engine mount design on the rattle and whistling noise audible from the engine mounts when the vehicle is subjected to rough road conditions and pot holes at slow speeds. The test methodology demonstrates how to simulate and co-relate the actual vehicle level noise on a BSR 4 poster test rig. A design change is proposed to abate the rattle noise from engine mounts considering the numerous variables involved and without affecting the critical NVH (Noise, Vibration and Harshness) and durability performance parameters. The level of noise reduction achieved is quantified through the substantial reduction in BSR demerit score which in turn reflects the improvement in perceived quality of the vehicle, increased customer satisfaction index and improved JD power (JDP) ratings