THE PROPOSAL FOR A NEW SHORT HOMOLOGATION TEST OF THE CI ENGINE CYLINDER-PISTON ASSEMBLY

摘要

In this paper we have presented the proposition of the new 60-hour homologation test of the cylinder-piston assembly of CI engines and the criteria for the evaluation of its wear by the end of its working life on the basis of the results of the test. The testing and defining of the criteria have been performed in the IMR Institute, on the basis of years of experience in the homologation of the cylinder-piston assemblies using the standard 500h test, durability tests of various prototype engines (which are not shorter than 500h) and the data collected from the engines after the end of their working life. Analyzing these results the conclusion was drawn that it is possible to predict the cylinder-piston assembly wear after only 60 hours of testing, using the new criteria which we have developed and presented in this paper. Our research was based on these premises: cylinder-piston assembly obeys the law of the wear changes depending on the time; the evaluation of the length of working life of some machine part is possible to perform on the basis of the wear of the surfaces in friction contact after a certain period of time; proposed test is applicable on the other parts of the main engine mechanism because the cylinder-piston assembly is exposed to the extreme thermal and mechanical loads; the database formed for this research contains the representative sample of CI engines for the similar applications, which is sufficient for the estimation of the test and criteria. The results have been statistically processed and the criteria are presented in percentages of the highest permitted values of wear after the end of the characteristic periods of the standard test, which are adopted as wear tolerances. This method has been tested on several engines and the results show that the wear of the part being homologized can be estimated with sufficient certainty. The purpose of this paper is to present a possible alternative method for the long-term and expensive standard homologation tests, which take significant part in the engine's date of appearance on the market.