The Technology Research Of Engine Assembly Error Analysis And Performance Prediction

Assembly is the final link in engine manufacturing process, which is also the most important and takes the most time over the entire engine manufacturer. Engine is a large mechanical products, its structure is very complicated. The accuracy of the engine assembly have a very important effect on the fatigue life of components and the operating performance of the engine. Therefore, the study of assembly errors of the critical engine parts is very important. Due to the sealing of the engine combustor and the precision of crank linkage assembly are the important index that evaluates the engine assembly quality and work performance, so this article will further study of the assembly error of crank connecting rod mechanism and the combustion chamber. For the assembly of crank and connecting rod mechanism, the precision of crank linkage assembly not only significantly affect the output power of the engine, and its assembly errors will be passed to the piston and cylinder wall, thus affecting the sealing of the enginer combustor. For the assembly of the engine combustor, the engine combustor is composed of cylinder, cylinder head and piston etc. The sealing of the engine combustor divided into the Sealing of the joint surface of cylinder and cylinder head, and the Sealing of piston and cylinder wall. The assembly way of sylinder and the cylinder head is threaded connection. The size of the bolt preload and the preload sequence effect the deformation of the connecting and the connected member, and also have a essential effect on the sealing of the joint surface. Specific contents are as follows:(1) First of all, the engine assembly error were studied in this pape. Than analysis of the assembly error factors influencing the performance of engine power. And analyzes the transmission mechanism for error source. In the end, calculates the clearance error between the piston and cylinder on the engine key parts deviation information.(2) Respectively set up block, cylinder head, cylinder head gasket, crankshaft, connecting rods and other critical engine parts using CATIA Part Design module. And respectively to complete the assembly of the ideal model and error model according to the engine key parts deviation information.(3) Respectively establish kinematics and dynamics simulation to the ideal model and error model(Geometric Position Error Model, Size Deviation Model, Rigid-Flexible Coupling Model) of Crank and Connecting Rod Mechanism in ADAMS. And to obtain the performance parameters at the engine working and actual working condition of engine internal load.Comparing the performance parameters of the output and to obtain assembly error influence on engine performance.Geting the actual working condition of the load as a foundation for the next step of analysis separation surface stress in ANSYS.(4) The finite element simulation analysis to sealing of the joint surface between the engine cylinder block and cylinder head.Due to the engine for the large complex entity model, in order to reduce the calculation time, increase work efficiency, so this paper will use the finite element pre-treatment powerful Hypermesh12.0 software to divide mesh.Then load the the actual working load obtained form the above on solid model in the ANSYS, and obtaine separation stress of the joint surface between the engine cylinder block and cylinder head.Finally, according to the value of separation stress on the joint surface under the actual load condition reversal to calculate the value of the bolt pre-tightening force.