Transient thermal analysis of mixed-elastohydrodynamic contact of high performance transmission in a dry sump environment

Abstract

Fuel efficiency is one of the main concerns in the optimization of modern racing transmissions. The dry sump transmissions are the preferred choice for high performance racing applications. While it provides adequate lubricant for gear contacts, it minimises the system churning losses, and therefore enhances the system efficiency. An important aspect is assessing its thermal performance in removing the generated frictional heat. The generated heat in the highly loaded high shear contacts of racing transmissions should be dissipated through use of directed impinging oil jets and in an air-oil mist environment. The paper presents an integrated tribological and 3D computational fluid dynamics analysis for a spur gear pair, incorporated into an overall finite element model to evaluate the quantity of generated heat and its removal rate from the rotating gear surfaces. Furthermore, the temperature distribution in the circumferential direction is predicted and used to evaluate transient temperature distribution over representative race laps. Such an approach has not hitherto been reported in literature.

A system level computational model for thermo-tribological functioning of high-performance racing transmission with dry sump lubrication

“…The thermal analysis is performed using the integrated multi-physics model. Both the system model (multiple gears) and the component model (single gear as reported by Fatourehchi et al 29 ) are conducted. This is to investigate the effect of multiple oil jets on the convection heat dissipation rate.…”

“…A finite-element method is used to evaluate heat conduction of a gear pair in a dry sump environment. In this study, the introduced transient model of one gear tooth with a single oil jet 29 is further developed. Another gear with a connecting shaft is added to the model.…”

“…This indicates that heat dissipation through convection to ambient and conduction to the adjacent gear teeth as well as the connecting shaft is the only heat transfer mechanism during the rest of tooth rotation. Considering such concerns, Fatourehchi et al 29 recently developed a transient finite-element model of a gear tooth with a single oil jet to predict the real-time temperature distribution of the tooth under a race condition. Modelling a single gear tooth does not take into account the heat dissipation through adjacent jet-lubricated unloaded gears which required a system approach.…”

Influence of Nozzle Layouts on the Heat-Flow Coupled Characteristics for Oil-Jet Lubricated Spur Gears

“…Convective heat exchange occurs between lubricating oil, surrounding air, and solid gears. Considerable amounts of frictional heat are transferred by lubricating oil to push the gear to achieve a heat balance with the surroundings in the event of an excessive temperature, and thus heat convection of the meshing area is also closely related to lubricating oil [16][17][18]. Previous thermal elastohydrodynamic lubrication studies were limited to the distribution of temperature gradients in local contact areas.…”

Improvements in the mixed elastohydrodynamic lubrication and in the efficiency of hypoid gears

“…Only some of the related papers are referenced. [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19] The first paper on the full thermo-EHL analysis of gears was published in 1981. 20 In the last decades, many research works are directed towards the EHL analysis in different types of gears.…”