Bauteilnahe Testmethodik für Grenzreibungszustände von Gleitlagerungen

Translated title of the contribution: Component near test methodology for boundary lubrication of journal bearings

Philipp Bergmann

Research output: ThesisDiploma Thesis


Market, the environmental situation as well as the legislator demand constant reduction of polluting emissions of internal combustion engines. To satisfy this demand actions in downsizing and light weight design are performed to increase the specific performance. Furthermore lubricants with low viscosity are used to reduce friction losses and to increase the overall efficiency. The increasing hybridization of vehicles is a further action to reach the ambitious aims. Under theses circumstances the Start/Stopp technology as basic module of every hybrid class takes an enormous boom. The performed actions imply hindered conditions of operation for journal bearings and enlarge the area of boundary and mixed friction, in which journal bearings show a reduced carrying capacity, over a widened area of rotational speed. This situation gets worse due to Start/Stopp technology, which means for journal bearings a frequent passing through these areas of critical speed. Conventional journal bearings are not laid out for this kind of load, why it is necessary to push forward development. In the course of this diploma thesis a methodology to perform cheap and component equivalent tests at a reduced journal bearing system was developed based on former works. Therefore a journal bearing adapter in combination with a rotational tribometer TE92HS was used. Several material combinations were examined whereupon FVA oils were used as lubricants. The conclusions, which can be deduced from tests should provide the base for future development of the tribosystem itself or parts of a tribosystem. At the beginning of the thesis a comprehensive literature research was conducted, which included basics of tribology and journal bearings. For the following practical part of the thesis it was necessary to study the structure of journal bearings inclusive the used materials and the functionality of the Start/Stopp technology and its impact on journal bearings. To be able to perform tests in the area of boundary and mixed friction mechanical work needed to be done to increase exactness of measurements and provide technical preconditions. Two new measuring instruments got installed. On the one hand a sensor to measure acoustic emissions and on the other hand high speed data acquisition to measure data of coefficient of friction, contact potential and rotational speed with high frequencies. The measurement of the hydrodynamic pressure, which was installed during former works, delivered dependable results for the first time due to the improvements of the mechanical set up. These components upgrade the frame of already existing measured variables to make rich in content statements. Tests are assisted by hydrodynamic simulations performed with COMSOL, which were used to validate the performed actions on the mechanical set up and together with the measured variables of tests deliver a wide base to describe tribological systems. Performed tests show that the methodology delivers detailed statements of tribosystems behaviour. Influences of temperature, load, state of surface and material combination can be visualized. It turned out that the high speed data acquisition enables a possibility to evaluate future improvements of the mechanical set up. Finally recommendations and future steps were discussed.
Translated title of the contributionComponent near test methodology for boundary lubrication of journal bearings
Original languageGerman
  • Grün, Florian, Supervisor (internal)
  • Summer, Florian, Co-Supervisor (internal)
Award date13 Dec 2013
Publication statusPublished - 2013

Bibliographical note

embargoed until 11-11-2018


  • Tribology
  • Journal bearing
  • Boundary friction
  • Mixed friction
  • Methodology
  • Journal bearing equivalent system
  • Start/Stopp

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