Abstract
Keywords:
Starter Noise, Design of experiments, Noise source identification
Abstract
The starter motor noise is usually well identified by the customers since it is operated while the engine is quiet, and leaves distinct impressions of the vehicle. In this study DOE was applied to identify the noise source of gear reduction type starter motor with field coil in yoke since this process usually requires lengthy analysis and elaborate experiments. In the first stage of DOE, five factors, excluding static unbalance, are sorted out of all possible factors, which are considered as controllable independent variables. Overall noise level in dBA was the objective function of the smaller-the -better characteristics. The test results showed that the dynamic unbalance and misalignment of armature are the major factors. However, the error level of the first test was relatively high, indicating that there might be some missing major factors. In the second stage test the results showed that both static and dynamic unbalances are the dominant factors contributing to more than 80% of the overall noise, while the misalignment contributes around 12%. Error of the second test was about 4% that could be considered satisfactory. The noise level of the optimal product was predicted to be reduced by 19dBA, and verification test showed the average noise reduction of 16.8dBA with the standard deviation of 3.2dBA, and proved the usefulness of the whole DOE process.