In recent years, automobile demand in the Indian market is growing up exponentially with more and more world-wide automobile manufacturers entering the Indian market. This has put tighter criteria in developing an automobile with the best overall performance at lower cost for the OEMs and auto component manufacturers to consider different aspects of a product during development stage. Noise, Vibration and Harshness (NVH) is one such product aspect, which is the most sensitive comfort requirement of an occupant and product quality cum cost to the manufacturer. With continuous improvements on noise reduction from the primary sources e.g. power-train and its sub-components of an automobile, the noise eminent from other sources like HVAC, wind, brakes, wipers etc. have become more perceivable to the in-vehicle occupants, especially for the car and SUV segment. This has made NVH as one of the key aspects of customer complaints or warranty, also applicable to auto-ancillaries, which are related to the product quality and consistency.
This paper deals with reduction of low frequency “clonk” noise, observed as a warranty claim on a Dual Proportioning Valve (DPV) used in an automobile hydraulic brake system. These valves are produced in large number with very low occurrence of noisy sample and this was to be brought down to ZERO. This was achieved with the aid of comparative analysis on noisy (NG) and non-noisy (OK) DPV assemblies based on the noise characterization and FRF based analysis. The root cause of the clonk noise was identified and its mitigation countermeasures were implemented within given design and production process constraints.