Performance Analysis And Optimization Of6M Motor Brake Air Compressor Crankshaft

As an important part of automobile braking system, the safety and reliability of braking air compressor are of great significance for people’s daily life. In addition, Vibration and noise which air compressor produces can pollute the environment and do harm to people’s physical and mental health. Crankshaft is a critical component of air compressor, whose performance can have a great influence on the whole machine. Therefore, the dynamic and static analysis on crankshaft plays an important role in improving the air compressor machine. In this paper crankshaft of a vehicle braking air compressor of6M is studied. Based on the design requirements, dynamic and static analysis to the6M crankshaft is carried out. What’s more, the crankshaft structure optimization and its improving measures are also put forward. Three optimization schemes are determined in the end of the paper.The main contents are as follows:1) According to the basic calculation parameters of automobile brake air compressor, the mechanism motion and crankshaft force of the connecting rod is analyzed calculation parameters include:geometric properties of the crankshaft、 the theory of displacement and the input power. Using simulation MATLAB software and simulation software ADAMS, piston displacement, piston speed, piston acceleration under variation with crank angle are obtained. Based on that, dynamics analysis of the various parts are finished, thus crankshaft load rule and characteristics in the process of working is got.2) Based on the mechanics model of connecting rod of air compressor crankshaft, the stress of the crankshaft for each turn60degrees and the crankshaft stress of six angles are calculated. The stress contours and strain contours、 the risk and the values of maximum stress and maximum deformation position of six kinds of working conditions are all obtained by using the static analysis. The results that obtained can meet the requirement of strength and stiffness of the crankshaft. The first eight order natural frequency and vibration mode are calculated by the using of modal analysis for a crankshaft. During the process of calculating, crankshaft resonance must be avoided caused by the approach of external excitation frequency and inherent frequency. 3) Based on the analysis of dynamic and static and software ANSYS WORKBENCH, a optimization model of crankshaft structure is built up.Making the largest composite stress of crankshaft as optimized object, choosing spindle neck diameterD1, crank pin diameterD2, spindle neck filletfl, spindle neck filletf2, crank pin filletf3and crank pin filletf4as design variables,The results of the three optimization schemes are as following:The largest composite stress calculated in scheme A is reduced by27.44%. The largest composite stress calculated in scheme B is reduced by27.96%. The largest composite stress calculated in scheme three is reduced by29.71%.Through the comparison of the three schemes above, scheme C has the best optimization effect. Scheme C is chosen as the final optimization scheme. Crankshaft fatigue analysis is based on the maximum stress after optimization. Crankshaft fatigue cumulative damage factor is0.0625, crankshaft life is16years.