246 TRANSMISSION COMPONENTS 15 24715 TRANSMISSION COMPONENTSSchaeffler Symposium 2018 customer requirements such as the design space and performance as well as take into considera tion all design and manufacturing restrictions Figure 7 For this purpose Schaeffler has developed the OptiKit optimization tool and integrated it in Bearinx With OptiKit users can integrate deve lopment goals and restrictions of their choice in the optimization and thus quickly find a system adjustment that meets the opti mum design and spec trum requirements The use of OptiKit can be demonstrated using the example of a friction optimized ta pered roller bearings on the pinion flange and pinion head of a rear axle transmis sion Figure 8 In the end friction was re duced again by more than 20 compared to the X Life T29D designs which were already low fric tion As criteria that are critical to functioning such as internal load distribution and contact pressure curves are included the required ser vice life is ensured In their initial condition the two bearings analy zed have a friction loss of nearly 12 Wh in a refe rence cycle for the design Here the opti mization goal is to re duce bearing friction without having to touch other boundary conditions such as manuf ac tur abil i t y design space and ser vice life requirements Step by step the OptiKit algorithm now approaches other pa rameter combinations that allow the reduc tion of friction losses which at the same time causes the ser vice life of the bearing to decrease It is only through an additional boundary condition that the service life requirement can be maintained during optimization Figure 9 shows the develop ment of the system friction and the service life evaluation over the course of the optimization run The optimization progression shows two areas that impressively demonstrate the new approach The system is consistently tuned towards permis sible design limits which results in a 15 friction reduction compared to manual bearing design Next the system is optimized further by adjusting the bearing precisely to the application in ques tion At the end of the optimization there is a bearing that was op timized with the spe cific characteristics of the adjacent system and the customer s development goals in mind The parameters that play a role here are shown in Figure 10 for the pinion head bearing and the pi nion flange bearing Inner diameter Outer diameter Bearing width Undercut width Contact angle Pitch diameter Rib width Number of rolling elements Rolling element diameter Rolling element length Rolling element chamfer Rolling element profile type Rolling element end face surface roughness Inner ring profile type Inner ring profile drop Outer ring profile type Outer ring profile drop Rib angle Rolling element end face radius Outer ring surface roughness Inner ring surface roughness Rolling element profile drop Rib surface roughness Rolling element surface roughness 6 Variety of parameters and influencing factors in the design and optimization of transmission bearings using a tapered roller bearing as an example D es ig n pa ra m et er s Lifetime requirements Design space requirements Suggested tuning D es ig n pa ra m et er s Design parameters Global optimum Design parameters 7 Comparison of the function of a classic optimization algorithm left and a real life optimization based on development requirements right 8 9 10 11 12 13 0 50 100 150 200 21 15 Ra tin g lif e re qu ire m en t Fr ic tio n lo ss in W h Iterations 8 Model of the rear axle drive to be optimized in Bearinx 9 Curve of the determined friction energy and service life evaluation based on optimization Both values are calculated using different design cycles that represent the respective target requirements

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