Horizontal Two-cylinder Diesel Engine Cylinder Head Heat Engine Coupled

The cylinder head is one of the most complex parts in the engine, the under side forms the combustion chamber with the top of piston, which endures high thermal and mechanical load during working cycles. Designed for marine and agricultural machinery and aiming at the existing technology problems of horizontal, one-cylinder or two-cylinder-diesel engine, the new, horizontal 2D25 diesel engine was designed and created for oneself. With the development of science and technology and the increasing of awareness to protect our survive environment, the demands for engine with better performance in operation, consumption, emission, noise, etc, has become more and more urgent. To meet these demands, a series of new technology are adopted, which means engine does bear higher mechanical load and thermal load. Furthermore, light-weight design method is adopted broadly. Thus the problem of engine structure liability is more serious than before. So during the course of designing, calculating and analyzing the temperature distribution, mechanical force field, and thermal stress distribution and thermo-mechanical coupling stress distribution that hot and mechanical load act on together in conformity with the force field of cylinder head. Finding out the hot load state of the cylinder head and comprehensive stress distribution situation to improve the cylinder head and its working dependability is significant.To obtain the temperature values of key dots in the fire deck surface of cylinder head under the declared working condition, adopted rigidity-plug temperature measurement method to test the temperature of key dots, analyzed the distribution condition of working temperature on the fire deck surface of cylinder head. Using the thermocouple to measure the temperature of the key dots which on the bottom surface of cylinder head. Through the temperature value that is measured, have calculated and analyzed the temperature field and heat stress distribution of the cylinder head under the declared working condition, also to analyze the differences between calculation temperature and tested temperature. Meanwhile, this paper also calculated and analyzed the mechanical stress of cylinder head include the preload pressure condition and the peak pressure condition, and the thermo-mechanical coupling stress field of cylinder head,which all under the declared working condition. Comparative analysis of the thermal stress and mechanical stress results to understand which one has made a dependence effect to the thermo-mechanical stress distribution.Through the above finite element analysis and temperature field research, we have had the results of the temperature field and the stress field and thermo-mechanical stress of the cylinder head. The calculation results show that the highest temperature of the cylinder head under the declared working condition is 346.3℃; The maximum thermal stress reach to 223.8MPa, occurs in the area where the largest regional temperature gradient have; The maximum mechanical stress is 208MPa. occurs in the places where the cylinder head bolts are installed; When the thermo-mechanical coupling stress work on the cylinder head, the maximum stress reach to 231MPa which on the bridge of the nose area of the cylinder head; The deformation of cylinder is not large, the maximum value of the cylinder head deformation is 0.102mm when cylinder working under the thermo-mechanical coupling stress; To sum up, the cylinder head has met the job requirements. This analysis methodology offered certain theoretical foundation for development and improvement of the new horizontal diesel engine cylinder head and provides a reference for the finite element analysis of other series of products.