The Key Technology Of The Diesel Engine Design Phase Reliability Study

Diesel engines played an essential role in the national economy as power suppliers for vehicles, construction machinery, ships and power-station machines. Reliability was significant to warrant the running of diesel engine as an important technique.In the design stage of diesel engines, separated reliability jobs couldn't afford the needs of improvement for diesel engines'reliability and got the expecting effect because of lacking an integrated framework for them. Furthermore, separated reliability jobs were always leading to low efficiency and reworks. It increased loads to designers, complained and boycotted by them. It decreased advances from the reliability jobs. This thesis presented a framework for the reliability jobs in the design stage of diesel engine by analyzing the reliability works in the engines'life cycle for meeting this condition. It integrated the failure mode and effect analysis (FMEA), failure data analysis, reliability allocation and reliability prediction into this framework and studied the key techniques and methods.We revised the traditional FMEA mode which based on the risk priority number in order to use it in the design stage of diesel engines. The preventing measures and detective measures were divided and evaluated, and then two detection indicators were being got after evaluation. A new failures risk sorting and processing principles were proposed based-on two different risk priority numbers. Additionally, a fuzzy logical inference method was used in the FMEA failure risk sorting process. It took some advantages, especially easy to understand for designers. Furthermore, a case study was offered in two methods, FMEA sorting method which included two risk priority numbers and FMEA sorting method based on the fuzzy logical inference, and then got the similar results.The sources of failure data and their features in the whole engine life cycle were analyzed. Also, this thesis proposed an analysis process for the first failure data of engines. Additionally, the field date of diesel engine maintenance was analyzed based on the FMEA jobs.The reliability allocation indexes and their transformation were discussed and then proposed a new allocation method based-on the reliability variation. The coefficient of the variation could be obtained using a comprehensive evaluation based-on the analytical hierarchy process. In the process, the authority of experts could be measured by coefficient of authority.At last, this thesis discussed seven facets in the reliability prediction problem. It generalized different facets in the reliability prediction. Additionally, a new prediction method was proposed which based on the reliability variation. It combined with the FMEA for diesel engines and then it was possible for reliability prediction updating company with the FMEA's update.