Aspects in the Synthesis of a Variable Compression Ratio Mechanism

CAR2017 International Congress of Automotive and Transport Engineering - Mobility Engineering and Environment

工业技术;运输工程

Mnescu, Bogdan^1 ; Ionu, Dragomir^1 ; Nicolae-Doru, Stnescu^2 ; Nicolae, Pandrea^2 ; Adrian, Clenci^2 ; Dinel, Popa^2

AKKA ROMSERV Bucharest, Romania^1

University of Piteti, Piteti, Romania^2

关键词: Approximate solution;    Characteristic elements;    Characteristic point;    Constraint functions;    Continuous functions;    Numerical procedures;    Triangular elements;    Variable compression ratio;   

Others  :  https://iopscience.iop.org/article/10.1088/1757-899X/252/1/012075/pdf
DOI  :  10.1088/1757-899X/252/1/012075

学科分类：工业工程学

来源: IOP

【 摘 要 】

The mechanism considered in this paper is a VCR one consisting in a crank, a shaft, an intermediate triangular element and a control lever and it was described in previous papers of the authors. The authors start from a classical crank-shaft mechanism for which the extreme positions are known. The first stage of the synthesis consists in determination of the constraint function which has to be fulfilled by the new mechanism so that the extreme position remain unchanged. The new step consists in imposing new conditions for the mechanism so that some new positions have to be obtained. The main hypothesis is that the positions of different characteristic points of the mechanism may be written as continuous functions of the certain input data. Due to aspect, the synthesis of the mechanism implies continuous variations of the output data and, consequently, there exists at least one solution for the synthesis process. In each case the authors determine the extreme positions of the piston. These extreme positions are also continuous functions of the input data. Two main approaches are discussed in the paper. One approach consists in the exact determination of the solution using a numerical procedure. The second one is an approximate one and consists in the determination of an approximate solution of the synthesis and verifying the deviation of this solution. For the new mechanism obtained by synthesis the authors determined the reduced velocities and accelerations of different characteristic elements. Some aspects of the wear are discussed with the aid of the reduced relative velocities.