The Influence Of Variable Compression Ratio On Engine Performance And The Optimal Design Of Mechanism

Variable Compression Ratio(VCR)technology,medium and small load conditions can effectively improve engine power and economy,and can avoid knocking under heavy load conditions.This paper simulates and calculates the variable compression ratio coupled EGR technology For the potential to improve engine performance,a variable-height piston mechanism program was designed and optimized.This paper uses GT-Power software to establish a simulation model of a 1.4L direct-injection gasoline engine and verifies that the model is in good agreement with the original engine.The engine has been studied under different technical strategies at a speed of 2000r/min and different load conditions.The changes of various performance parameters are analyzed,and the potential for improving engine power and economy of the variable compression ratio technology under lean-burn conditions is analyzed.This paper compares and analyzes several variable compression ratio piston mechanism schemes designed in the early stage,compares the advantages and disadvantages of the hydraulic and electric drive modes,and finally determines the motor-driven variable height piston mechanism scheme,which is based on the entire ZS1100 single-cylinder engine Parameters are optimized,the original piston is designed into three parts: the upper piston body,the intermediate body,and the lower piston body.They are connected by trapezoidal threads,the torque transmission path is selected,the transmission mechanism is designed,and the 12 V DC drive with planetary reduction gear is selected according to the size of the piston pin.Motor,optimize the details of the matching of various parts.This paper uses CATIA software to establish a three-dimensional model of VCR piston components,and conducts mechanical stress simulation and thermo-mechanical coupling simulation on the VCR piston through the ANSYS Workbench finite element simulation platform,and analyzes the VCR piston under extreme compression and tension conditions.The mechanical stress and strain situation,the distribution cloud diagram of the stress and deformation of the various parts of the variable height piston under the actual boundary conditions are obtained,which verifies that the VCR piston mechanism can meet the design requirements,and analyzes the VCR piston under the simultaneous action of thermal load and mechanical load Changes in the amount of stress and deformation.At the end of this paper,the machining drawings of the various parts of the mechanism are drawn based on the three-dimensional model of the VCR piston,and the assembly test of the processed objects is carried out,and the feasibility of the mechanism is initially verified by electrification.