NVH Assessment, Source Identification and Noise Control of Excavator

Abstract

Noise, vibration and harshness (NVH) has gained importance in the field of off-highway machinery. Most of the countries have adopted stringent exterior and in-cab noise emission norms for such machinery. Hence it is important to consider NVH in design phase itself to accomplish legislation requirements. The objective of this study is to develop method to reduce noise and vibration problems related to exterior noise and in-cab noise of the excavator machine. Machine noise is the combination of mechanical noise, combustion noise and flow induced noise. During operating condition machine emits airborne noise, structure borne noise and fluid flow noise. Hence it is essential to identify transfer path of noise and vibration generating sources. Noise source ranking of the machine according to noise emission helps to identify dominating noise sources. Optimization of mount effectiveness and increased air intake and exhaust system insertion loss has helped to achieve legislation requirements in most of the cases. The change in engine mounted fan assembly from fixed fan to variable speed fan has significantly affected overall machine noise level. Combinations of these techniques have achieved machine exterior noise reduction by 3dB and in-cab noise reduction by 2dB of the excavator.