Research On Block Assembly’s Structural Design Compatibility Of Mid-Heavy-Duty Diesel Engines

Mid-heavy-duty diesel engine is widely used, but the diesel engines’design work has been always depending on internationally renowned companies such as AVL, FEV etc., which intangibly creat a technical barrier to domestic diesel industry. This paper make a research on several widely used and technique matured mid-heavy-duty diesel engines, making numerical analysis on engine parts and block assembly, and then summing up experience on structural design compatibility, providing reference data for the mid-heavy-duty diesel engine design work.In this paper, the finite element calculation is used to extract imaging stiffness of the key structure of diesel engine block assembly. On one hand, it’s used to evaluate the design of individual parts, on the other hand, it’s associated with the block assembly stiffness after dimensionless, to analyze the block assembly structural compatibility.The detail works are as follows:1. Creat finite element models of diesel cylinder head, liner and block, calculate the imaging stiffness of key structure, and dimensionless according to character. Compare the dimensionless volume and dimensionless stiffness, the results show that the dimensionless volume and dimensionless stiffness of several key structure of cylinder head and cylinder liner distribute within a certain range, it’s has a high meaning on guiding the structural design of cylinder head and liner.2. Based on the middle part oriented stiffness of more than ten kind of axial positioning of the upper end wet liner, and then using the response surface method to get the function of oriented stiffness and liner inner radius, wall thickness and span length for radial double support, thin-walled cylinder liner. And this can be directly applied to the liner structural design.3. Calculate on engine block assembly, extract the dimensionless stiffness of three key structure in the assembly state, and then using response surface method to get the compatibility of assembly stiffness and discrete parts stiffness.4. Conduct CFD calculation of cooling system, extract the temperature and convective heat transfer coefficient of the water cavity wall as a third type of boundary condition applied to the finite element model. Calculate the temperature distribution of the block assembly, make it the thermal boundary conditions for liner deformation.5. Calculate liner deformation on four case based on cold and hot states. Put up maximum and minimum effective deformation, effective roundness error and effective cylindricity error to assess the liner roundness deformation and put up distortion coefficient to assess liner distortion, then put forward the concept of tortuosity to evaluate liner distortion comprehensive.6. Apply response surface method to get the campatibility function of liner distortion and block assembly stiffness. The results display that explosive peak pressure has littlt effect to liner distortion and temperature’s effect is linear.