Thermoelastohydrodynamische Betrachtung des Kolben-Buchse-Kontakts in Hochdruckpump

  • Thermoelstohydrodynamic consideration of the piston/cylinder contact in high-pressure pumps

Fischer, Felix Lukas; Schmitz, Katharina (Thesis advisor); Rienäcker, Adrian (Thesis advisor)

Düren : Shaker Verlag (2021)
Book, Dissertation / PhD Thesis

In: Reihe Fluidtechnik 105
Page(s)/Article-Nr.: xii, 150 Seiten : Illustrationen, Diagramme

Dissertation, RWTH Aachen University, 2020

Abstract

The global challenge of reducing CO2 emissions in the transport sector and the ever stricter exhaust gas legislation for gasoline and diesel engines has manifold and fundamental effects on the periphery of the internal combustion engine. In modern diesel engines, which are powered by a common rail system, there is a need for the fuel to be atomized as finely as possible. One way to achieve this is to increase the injection pressure. In the common rail high pressure pump, the piston/cylinder contact is therefore subject to an increasing load. The sealing gap between piston and cylinder, which is in the order of a few micrometers, must seal the high rail pressure of up to 3.000 bar. The temperature increase that the fuel in the sealing gap experiences leads to a deformation of piston and cylinder as well as a deterioration of the efficiency of the pump due to increased leakage. The numerical mapping of the critical piston/cylinder contact in the high pressure pump must be able to be carried out safely for the design.In the present work a microgap test rig is developed and tested, which allows the validation of this calculation on an abstracted level. Therefore, a concept study for the different abstraction levels of the tribological test chain is carried out and the requirements for such a microgap test rig are determined. In the following a design is presented and manufactured. The special boundary conditions and sensitivities of the test stand development are discussed. The functional verification of the microgap test stand is carried out with up to 3.000 bar operating pressure. The reproducibility of the results is proven and the characteristics of the high pressure microgap are described. A sensitivity and robustness analysis is then performed. Using a TEHL simulation, the most important physical effects in the microgap are identified and discussed. The further analysis includes special effects of the present tribocontact. Furthermore, the suitability of the microgap for the validation of a commercial TEHL tool is discussed. To close the tribological test chain, two further levels of abstraction will be developed experimentally and the results of the microgap tests will be transferred to these levels.

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