Design Of A Variable-connecting VCR Engine And Analysis Of The Main Parts

With the energy situation has become more critical, more stringent emission, the modern engines have been pursuing high-power, high-performance, low-power, high life expectancy, low pollution, diversification and new structures. However, General engine failed to meet that has good dynamic performance but also has good fuel economy and emissions.And the problems of the engine at idle condition, at starting condition and low load conditions are still not solved. Therefore, the research of engines focus on the development of low power consumption, high power.According to the design team for the invention patent "variable connecting rod type VCR engine connecting rod mechanism", the structure and dynamic properties of a variable connecting rod type VCR engine mechanism is studied. This paper studied a VCR(Variable Compression Ratio) engine of variable connecting rod. The main parts of the structure is designed and calculated by the reliability. And the three dimensional model is built. Finally the feasibility of the VCR mechanism is verified by using static analysis and dynamic analysis.The main research contents of this paper are as follows:①A variable connecting rod of VCR engine is proposed by the structural parameters of F1 C engine and design of National invention patent "variable connecting rod type VCR engine connecting rod mechanism" for the Research Group. This paper has took the crank and connecting rod mechanism of the VCR engine as the research object, realized a design that the compression ratio can be changed according to change the length of the connecting rod. The relationship of the change between the variable connecting rod and compression is analyzed and calculated by the motion law of the hydraulic cylinder and the connecting rod.②The working principle and stress of the crank and connecting rod mechanism of VCR engine is analyzed. The main parts of the structure sizes are determined and the strength is checked. The model crank and connecting rod mechanism is built by a 3D design software- CATIA V5,and provided a model for simulation study.③ Variable connecting rod simulated statics by a finite element analysis software-ANSYS Workbench. The stress and strain changes of connecting rod, piston rod and cylinder in Variable in the connecting rod were affected by the external stress are investigated. The rationality of VCR scheme and structure are verified.④The VCR engine mechanism has carried on the kinematics and dynamics simulation by dynamics analysis software-ADAMS. Effects of performance of the engine in different speed and different load are investigated. The feasibility of the VCR mechanism scheme is verified.The results show that: the proposed technical solution of a VCR mechanism of variable connecting rod mechanism is reasonable and practicable, the structure is basically stable, the main parts of the design to meet the strength requirements, and improve the engine power and emission can be achieved.