All Title Author
Keywords Abstract


Investigations on Oil Flow Rates Projected on the Casing Walls by Splashed Lubricated Gears

DOI: 10.1155/2012/365414

Full-Text   Cite this paper   Add to My Lib

Abstract:

In order to investigate the oil projected by gears rotating in an oil bath, a test rig has been set up in which the quantity of lubricant splashed at several locations on the casing walls can be measured. An oblong-shaped window of variable size is connected to a tank for flow measurements, and the system can be placed at several locations. A series of formulae have been deduced using dimensional analysis which can predict the lubricant flow rate generated by one spur gear or one disk at various places on the casing. These results have been experimentally validated over a wide range of operating conditions (rotational speed, geometry, immersion depth, etc.). 1. Introduction Splash lubrication is traditionally used in low- to medium-speed enclosed gears such as automotive gearboxes in which the lubricant is projected by the rotation of the gears. The main disadvantages are (i) the generation of significant power losses by churning and (ii) the absence of precise control in terms of lubricant supply. Based on a number of studies [1–10], there is general agreement on the fact that losses increase with rotational speed and immersion depth. Although lubricant churning can be considered as a major source of power loss in gearboxes, splash lubrication also contributes to the regulation of gear bulk temperature since some heat is removed from the tooth faces by centrifugal fling-off as demonstrated by Blok [11]. Using a general thermal model of an automotive manual gearbox, Changenet et al. [12] have confirmed the influence of the heat exchanges between the oil sump and several rotating elements on the global thermal behaviour and emphasized, in particular, the role of the immersion depth. H?hn et al. [13] have conducted a number of experiments showing that lowering the oil level in the sump reduces churning losses but also leads to higher gear bulk temperatures. These results have been theoretically confirmed by Durand de Gevigney et al. [14]. From the above-mentioned studies, it seems possible to define an optimal lubricant level in the sump in order to reduce churning losses and, from a thermal viewpoint, ensure satisfactory gear-lubricant heat exchanges. However, as far as the authors know, the influence of the oil level on the lubricant circulation and flow has received scant attention in the open literature despite the practical importance of ensuring sufficient lubrication and cooling of sensitive elements such as bearings. Because of its intrinsically chaotic nature, splash lubrication properties are hardly predictable and a lot of the development for

References

[1]  A. S. Terekhov, “Hydraulic losses in gearboxes with oil immersion,” Vestnik Mashinostroeniya, vol. 55, no. 5, pp. 13–17, 1975.
[2]  E. Lauster and M. Boos, “Zum W?rmehaushalt mechanischer Schaltgetriebe für Nutzfahrzeuge,” VDI-Berichte, vol. 488, pp. 45–55, 1983.
[3]  R. J. Boness, “Churning losses of discs and gears running partially submerged in oil,” in Proceedings of the International Power Transmission and Gearing Conference: New Technologies for Power Transmissions of the 90's, pp. 355–359, Design Engineering Division, ASME, Chicago, Ill, USA, April 1989.
[4]  B. R. H?hn, K. Michaelis, and T. V?llmer, “Thermal rating of gear drives: balance between power loss and heat dissipation,” American Gear Manufacturers Association Document, 96FTM8, p. 12, 1996.
[5]  P. Luke and A. V. Olver, “A study of churning losses in dip-lubricated spur gears,” Proceedings of the Institution of Mechanical Engineers G, vol. 213, no. 5, pp. 337–346, 1999.
[6]  C. Changenet and P. Velex, “A model for the prediction of churning losses in geared transmissions—preliminary results,” Journal of Mechanical Design, vol. 129, no. 1, pp. 128–133, 2007.
[7]  C. Changenet and P. Velex, “Housing influence on churning losses in geared transmissions,” Journal of Mechanical Design, vol. 130, no. 6, Article ID 062603, 6 pages, 2008.
[8]  S. Seetharaman and A. Kahraman, “Load-independent spin power losses of a spur gear pair: model formulation,” Journal of Tribology, vol. 131, no. 2, Article ID 022201, 11 pages, 2009.
[9]  G. Leprince, C. Changenet, F. Ville, P. Velex, C. Dufau, and F. Jarnias, “Influence of aerated lubricants on gear churning losses—an engineering model,” Tribology Transactions, vol. 54, no. 6, pp. 929–938, 2011.
[10]  C. Changenet, G. Leprince, F. Ville, and P. Velex, “A note on flow regimes and churning loss modeling,” Journal of Mechanical Design, vol. 133, no. 12, Article ID 121009, 5 pages, 2011.
[11]  H. Blok, “Transmission de chaleur par projection centrifuge d’huile,” Société d’Etudes de l’Industrie de l’Engrenage, vol. 59, pp. 14–23, 1970.
[12]  C. Changenet, X. Oviedo-Marlot, and P. Velex, “Power loss predictions in geared transmissions using thermal networks-applications to a six-speed manual gearbox,” Journal of Mechanical Design, vol. 128, no. 3, pp. 618–625, 2006.
[13]  B. R. H?hn, K. Michaelis, and H. P. Otto, “Influence of immersion depth of dip lubricated gears on power loss, bulk temperature and scuffing load carrying capacity,” International Journal of Mechanics and Materials in Design, vol. 4, no. 2, pp. 145–156, 2008.
[14]  J. Durand de Gevigney, C. Changenet, F. Ville, and P. Velex, “Thermal modelling of a back-to-back gearbox test machine: application to the FZG test rig,” Proceedings of the Institution of Mechanical Engineers J, vol. 266, no. 6, pp. 501–515, 2012.
[15]  S. Candel, Mécaniques des Fluides—Cours, Dunod, Paris, France, 2nd edition, 1995.

Full-Text

comments powered by Disqus