NGD3.0 Diesel Engine Research On Design And Sealing Performance Of Cylinder Head Gasket

With the continuous improvement of power and performance of diesel engine,higher requirements are put forward for its sealing performance.At present,researchers will improve the sealing performance of the engine,mainly focusing on the engine power and fuel combustion is adequate.As one of the important indicators of engine performance,the sealing performance of engine is mainly designed by the experience of designers,which hinders the improvement of engine sealing performance to some extent.This paper takes NGD3.0 diesel engine as the research object,designs the matching cylinder gasket of engine from the bottom of product development,and studies the sealing performance of the engine.The research content mainly includes the following parts:(1)The model reconstruction of diesel engine cylinder block and cylinder head is completed by using reverse engineering technology.The point cloud data of the engine was obtained by using Handyscan 3D handheld laser scanner,and the structural parameters of the complex water channel inside the cylinder head were obtained by using silicone turnover technology;The point cloud data is preprocessed by Geomagic Studio software,and the model reconstruction of cylinder block and cylinder head is completed in CATIA by using reverse / forward hybrid modeling method;In Solid Works,the forward modeling of the engine bolts is carried out,and the forward modeling of the cylinder gasket is carried out according to the subsequent two-dimensional drawings of the cylinder gasket,and the complete assembly of the diesel engine is completed.(2)According to the structural parameters and performance parameters of cylinder block and cylinder head of diesel engine,the matching cylinder gasket is designed.The material selection,structure selection and theoretical sealing force calculation of the cylinder gasket are completed;according to the cylinder block /cylinder head structure,the layout of the sealing rib is reasonably arranged,and the rib structures of the cylinder port,water hole,oil hole and bolt hole are designed,and the two-dimensional drawing of the cylinder gasket is drawn.Finally,the design of the cylinder gasket is completed.(3)In this paper,the nonlinear characteristics of cylinder head gasket are studied deeply.The compression and springback curve of cylinder head gasket is obtained by compression and springback experiment,and the material properties of cylinder head gasket are defined by compression and springback curve;Using ANSYS Workbench software,the nonlinear finite element analysis of the engine is carried out by using the method of simplifying the cylinder gasket;The results of the sealing force between the analysis data and the surface pressure experimental data are compared.The sealing force meets the sealing performance requirements,and the error is within a reasonable range.The rationality and reliability of the design of the cylinder gasket are verified.(4)Considering the influence of nonlinear factors,the influence of the thickness of the cylinder gasket seal coating and the thickness of the functional layer on the sealing performance of the engine was studied by using the method of simulated compression rebound experiment.The relationship between the thickness of the sealing coating,the thickness of the functional layer and the sealing performance of the cylinder gasket is obtained.The best thickness of functional layer and sealing coating is determined by interpolation fitting method.By adjusting the thickness of coating and functional layer of cylinder gasket,the sealing performance of cylinder gasket is improved.(5)The coupling analysis of NGD3.0 diesel engine with multi physical fields is carried out by using ANSYS Workbench software.The results of coolant velocity distribution,whole machine temperature distribution and whole machine displacement are obtained under the coupling effect of fluid thermal solid three fields.The sealing performance of diesel engine under the combined effect of coolant,thermal stress and mechanical load is explored.Through the above series analysis of the whole engine,it is verified that the designed cylinder gasket can meet the sealing performance requirements of the whole engine,and effectively improve the sealing performance of the engine.(6)The fatigue test of the designed cylinder head gasket of diesel engine is carried out.The stress and displacement of the cylinder pad under the action of 10 million mechanical loads are obtained through fatigue test.Finally,the designed cylinder pad can meet the service requirements of fatigue design life.