Calculation of the required minimum of a motor oil level on cylinder-piston group moving surfaces of the automotive diesel

Abstract

BACKGROUND: Theme of this article is actual because issues of the reliable and cost-effective opera-tion of augmented automotive piston engines are still not solved. An important aspect of solving the problem is rational oil supply of the cylinder-piston group. AIMS: The purpose of this work is the required minimum motor oil level estimation for the hydrodynamic lubrication of the cylinder-piston skirt pair. There were set and solved the tasks of determining the volume of motor oil capable of filling: 1) cavities of the flat-topped surface of the cylinder; 2) a raised surface of the piston skirt and 3) the piston skirt clearance. The object of study is an automotive diesel. METHODS: Three types of analytical determination of the total volume of the cavities of the rough surface and the piston skirt clearance were used as methods for estimation of a motor oil level. RESULTS: It was found, that the estimation with the well known formula for oil volume (a method 1) gives the overevaluated result of oil level estimation, in comparison with methods 2 and 3, which taking into account the real geometry of cavities and roughness parameters. The advantage of method 3 was determened by criteria of generalization and of simplicity to apply. Using the method 3, the estimated volume of motor oil ensured the hydrodynamic lubrication mode of the cylinder piston skirt pair of the object of study was obtained. CONCLUSION: The analytical expressions obtained by method 3 can be recommended to optimize the piston engine lubrication systems for reducing the friction and wear losses as well as to minimize a risk of oil starvation and increased oil consumption through burning.