2nd ICAI 2022

International Conference on Automotive Industry 2022

Mladá Boleslav, Czech Republic

correctness of the gear mesh, and it is obvious that it would be ideal from the point of view of load capacity to be continuous over the entire tooth surface with smooth ramp ups. Sudden sharp transitions cause step changes in the force effects in the gearing and consequently vibration and noise in the gearing, especially at the first harmonic tooth frequency. They can also induce stress concentration and thus create pitting. Figure 1: Examples of contact patterns, above are the one path contact patterns, below is the total contact patterns, on the left side of the figure the gear load is about 2 Nm and on the right side is 30 Nm

Source: Škoda Auto, a.s., internal materials However, the contact pattern is altered by various changes in the effects exerted during operation on the gearbox containing the gears and on the gearing itself. These effects are mainly due to changes in operating torque load, operating temperature and input speed (Figure 2). These operational changes and their combination, also due to the variation of the engagement stiffness due to the changing engagement duration, induce changes in the deformation of the different parts, so that these deformations are not constant during operation (Lewicky, 2016). Gearbox housings deform, shafts deflect, gear racks bend, bearings deform. The teeth themselves bend and their surface deforms. Figure 2: Example of a change in the contact pattern caused by different deformations of the parts, in this case caused by a change in the magnitude of the load (low load on the left, high load on the right)

Source: Škoda Auto, a.s., internal materials

38