Study On Design Of Automotive Exhaustmuffler And Its Expert System Development

Using exhaust muffler is the main way to control automotive engine exhaust noise.To this day, exhaust muffler performance precision prediction and accurate design is still a problem. Its design is still highly dependent on the experience. As a result, the design work of exhaust muffler is harder to grasp and many designers feel so confused. In the case of the domestic enterprises have yet to master the muffler core R&D technique, the development muffler design expert system has a great value to speed up the muffler design technique to transfer and promotion of industrial.First of all, by the approach of combination with the experiment and simulation analysis, it develops studies on the effect of a baffle seam on reactive muffler acoustics and the effect of the distance between inlet-tube and back wall in reverse flow extended-tube chamber muffler on pressure drop. It results three key conclusions:â‘ The baffle seam has undermined sound attenuation of resonant muffler or moves its resonant frequency.â‘¡In the reverse flow extended-tube chamber muffler, the distance between inlet tube and back wall has a greater impact than the outlet on pressure loss. In other words, if the inlet tube is shorter than the outlet tube, it can get a lower pressure loss.â‘¢There exists a critical distance between inlet tube and back wall in the reverse flow extended-tube chamber muffler. Less than this distance can cause pressure drop sharply rise. The critical distance is related to inlet-tube inner diameter. The discovery of objective laws is helpful for designers to choose parameters reasonably, and also reserves design rules and knowledge of the expert system for muffler design.Secondly, the performance evaluation of automotive exhaust muffler is still no unified approach and remains in the qualitative evaluation based on personal experience. This leads to the evaluation results arbitrary large and cannot be quantified. According to the present situation, it builds an evaluation system for multi-performance of automotive exhaust mufflers by establishing a series of indexes for each performance of mufflers and finds index's weighting base on Analytic Hierarchy Process (AHP). It shows that the evaluation system is suitable and feasible for multi-performance comparison by using the evaluation system to evaluate the measured results of 5 passenger car mufflers. This evaluation system can be used in comparing different mufflers quantitatively.Thirdly, by developing the reasoning technique of muffler design, its proposed solutions for case representation, case reasoning and case revise on muffler design. In particular, it presents a representation method of the internal structure of exhaust muffler, an algorithm for determining of structure topology relations and a means of judging reasoning results similarity. With those studies, it achieves case-based reasoning and rule-based reasoning in muffler design.Fourthly, aiming to expand the scope of reasoning in muffler design, it also developed rapid prototyping methods of exhaust muffler by feature-based parametric modeling technique and achieves automatic computing by secondary development of commercial FEM software.Finlay, it's built an expert system for automotive exhaust muffler design which names'ES2'. The system integrates a collection of functions such as reasoning, design, analysis. And a database with design cases, design knowledge and evaluation methods for muffler design is also included. Using the system for developing two cars'muffler, the measured results show that the system has a strong practical value and the designed muffler meets the practical requirements of engineering.The above studies cross vehicle engineering, artificial intelligence, image processing, management science and other fields. Comprehensive evaluation of the application of the muffler evaluation makes the design and evaluation more scientifically. The application of expert system in muffler design improves the design success rate. The techniques of automatic analysis and parametric modeling in the blend of the muffler design make the design more efficient. The Implement of the expert system for muffler design in automobile parts enterprises has practical significance to improve their muffler design level.