Investigation On Equal-intensity Lightweight Design Of Diesel Engine Block Based On Virtual Technology

Internal combustion engine (I.C. engine) industry has advanced rapidly in ourcountry, especially single-cylinder diesel engine. From 1992, China has been thebiggest supplier of single-cylinder diesel engine in the world. But our country'sresearch and development technologies in this field are still behindhand and based onthe traditional experience mode. Therefore, the single-cylinder diesel enginecompanies in home can not meet the demands of the local and international markets.Under the background, the modern design mode of diesel engine is conducted in thisthesis. S1100 diesel engine block from Sifang group corporation of Zhejiang provinceis investigated in order to reduce the weight of the block. The main contents are asfollows:Firstly, the paper describes the applications of Modern Design Theory andMethod in I.C. engine industry. Some technical issues are discussed, such as FiniteElement Method (FEM), dynamic design, optimization design, CAD/CAE, concurrentdesign and so on. It is concluded that virtual design will be the trend of modern I.C.engine design method.Secondly, the exterior vibration experiment on S1100 diesel engine is performedin this dissertation. In the experiment, the vibration rule of the whole engine is foundout so as to provide the necessary experimental data for the design of dynamiccharacteristics of the engine block. Meanwhile, the experiment on vibration severityof S1100 diesel engine is carried out to evaluate its overall performance and providesthe parameter for the evaluation of lightweight design of the block.Thirdly, the Finite Element Analysis (FEA) is applied in the light-duty design inorder to obtain the stress distributions of the diesel engine block. Some factors whichhave effects on the precision of numerical analyses are discussed in detail, such as thechoice of element type and size, the simplification of excitation loads, the definitionof boundary conditions and so forth. The Experimental Modal Analysis (EMA) isconducted to determine the natural frequencies of the engine block. The finite elementmodel of S1100 block is verified by comparing the FEA data to EMA data. Under twotypical operating conditions, the intensity of the block is calculated by the finiteelement software MSC NASTRAN. The acquired results are further analyzed, whichprovide the basis for the modification design of this engine block. Based on the stressdistributions, the paper conducts the lightweight design of S1100 diesel engine blockaccording to the equal-intensity and block design principles. Eventually, the FEM isreapplied to examine the intensity and the modal characteristics of the modified dieselengine block.Finally, the prototype of the modified block is manufactured with the weightreduction of 6kg. The modified diesel engine has passed the reliability testing for 200hours. The investigations on the vibration of the modified diesel engine are performed.The results show that the dynamic characteristics of the modified engine block is evenbetter than that of the original and then verify the rationality of the modificationscheme.Based on all of the work above, it is concluded that the modern design mode ofdiesel engine conducted in the paper is feasible and will be helpful for our country'sI.C. engine industry development in future.