A Certain Type Of Diesel Engine Crank Rod System Reliability Analysis

Diesel engine is civil and military vehicles, engineering machinery, ships and power station’s the main power units. The crank rod system of the diesel engine is the most important moving parts, which is responsible for the transformation between crankshaft rotation movement and piston linear motion. Due to big load and bad working environments, the crank rod system’s failure mode and failure mechanism are complicated and changeable, which restrict and affect the entire diesel engine’s reliability level directly.The paper makes crank rod system of the12150L diesel engine the research object. In the qualitative analysis of reliability, sums up finishing diesel engine crank rod system’s the failure, the failure mechanism and the harm influence. From the point of the kinematic accuracy of the mechanism, analyzes the piston of the crank rod system movement, and the impact of the key moving pair’s wear.From the angle of the reliability,study the distribution of institutions precision. The main content of this article are as follows:First of all, carry out failure mode and effect and harm degree analysis (FMECA) to12150L diesel engine’s crank rod system including the system definition, the whole organization’s failure mode and effect analysis of (FMEA) and harm degree analysis (CA), finally rolled into FMECA table and summarize the failure mode and harm, which is the reliability of qualitative analysis for the follow-up work.Then, apply effective length model and continuous contact model to crank rod system synthetically for the probability of crank rod system modeling. Deduce the expression of piston motion position errors’ mean and variance in the error analysis method. Analyse the affection of institutions wear simply, and deduce expressions of influence contains wear. Make parameters of12150L diesel engine calculation example and calculate its reliability. Carry out Monte Carlo method to it for the position error of movement simulation modeling analysis, whose results and theoretical derivation results are compared to test and verify the probability model of institutions, theoretical derivation expression and the reliability calculation method.Finally, to establish processing manufacturing cost objective function, design length dimension tolerance, pin and socket tolerance, and sports vice clearance, which are taken as variables, and determine the relationship between variables and all variables’ value range. Specify the reliability indexes as constraint conditions, use the optimization toolbox which MATLAB software provides for institutions precision optimization to find tolerance values and clearance value which produce the lowest cost. And with the different groups of reliability index and cost index plot a graph, analysis the relationship of processing cost and reliability to determine reasonable reliability indexes.