The purpose of this paper is to show these effects in an abstracted micro gap test bench. Because of stronger emission laws, the ambition to raise the rail pressure in common-rail systems from the current 2500 bar to 3000 bar is a given. The pressure increase will allow fine atomization of fuel and therefore more efficient combustion. But within the technical system of the high-pressure pump, stronger thermal stresses of the piston–cylinder contact are expected. A pressure drop from such a high level causes high temperature gradients due to energy dissipation.
For a detailed examination, the critical piston–cylinder contact has been investigated in an abstracted test bench with a flat parallel gap and an equivalent thermo-elastohydrodynamic simulation model.
The simulation results show good accordance to the measurements of pressures, temperatures and leakages for pressures up to 3000 bar. Comparison with elastohydrodynamic lubrication results outlines the need to consider temperature and pressure effects viscosity and solid deformation for the simulation and design of tribological contacts at high pressures.
This paper describes a simulation method with high accuracy to investigate tribological contacts considering temperature effects on solid structures and the fluid film. The thermo-elastohydrodynamic lubrication simulation method is valid not only for piston–cylinder contacts in high-pressure pumps but also for journal bearings in combustion engines.
The research project “Diesel 3000 bar” (project number 18193 N/1) was financially supported by the Federal Ministry for Economic Affairs and Energy (BMWi) via the German Federation of Industrial Research Associations (AiF) (IGF number 18193 N). The authors would like to express gratitude for the financial support and also for the support by the working group during the project within the Research Association for Combustion Engines eV (FVV).
Özdemir, Ö., Fischer, F., Rienäcker, A. and Schmitz, K. (2019), "Thermo-elastohydrodynamic simulation of the piston-cylinder contact in high-pressure pumps at 3000 bar", Industrial Lubrication and Tribology, Vol. 71 No. 5, pp. 702-705. https://doi.org/10.1108/ILT-05-2018-0169
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