Analysis of the Operational Behavior of a High-Speed Planetary Gear Stage for Electric Heavy-Duty Trucks in Multi-Body Simulation
Stricter emission limits accelerate the development of electric trucks, especially for urban distribution traffic. The use of electric motors instead of diesel engines confronts gearbox development with the challenge of higher engine speeds and higher requirements on transmission acoustics. Planetary gearboxes are often used for this purpose, as they allow high transmission ratios in reduced assembly space.
Dynamic multi-body simulation (MBS) is used for detailed dynamic modeling of drive trains. The interaction of gears and shafts in planetary gearboxes requires, especially for NVH-analysis, advanced simulation methods due to the sophisticated kinematics and the more sensitive displacement behavior. Dynamic simulation methods for cylindrical gears usually describe the tooth contact based on analytical equations or consider only one rotational degree of freedom, which leads to uncertainties in the simulation results. Misalignments are therefore, either simplified or not considered at all. The authors developed a method that combines the advantages of the quasi-static FE-based tooth contact analysis with the advantages of an integrated approach in the MBS.
In this paper the operational behavior of a high-speed planetary gear stage for electric heavy-duty trucks is analyzed in dynamic MBS. The method for the tooth contact analysis in the MBS is used for the simulation of planetary gearboxes. Different mesh sequences and model configurations for planetary gearboxes are compared and the effects on the operational behavior are evaluated. In addition to the dynamic transmission error, the dynamic tooth flank pressures are analyzed. Furthermore, dynamic misalignments in the tooth contact and the load sharing behavior in dynamic operating conditions are evaluated. In the simulation, the misalignment of the gears is directly taken into account by means of a penetration calculation in every time step. The presented method allows a well-founded prediction of the operational behavior of planetary gear stages, considering the dynamic interaction of the components.
Authors: Christian Westphal, Jens Brimmers, & Christian Brecher
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