NVH Analysis of an Axle Drive with Bevel Gearset

Abstract

This study evaluates the Noise, Vibration, and Harshness (NVH) performance of an E-Axle equipped with a bevel gearset. By analyzing the influence of pinion mounting distance (H), the study demonstrates how dynamic simulation and design optimization can minimize vibrations and improve acoustic performance. Results show that optimized mounting configurations significantly reduce acceleration amplitudes and sound pressure levels (SPL), providing valuable insights for efficient and reliable gear design.

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Introduction

Bevel gears are commonly used in automotive E-Axles to transmit power between intersecting shafts. Their spiral design enables smooth operation and enhances load capacity, but achieving optimal NVH performance remains challenging. Factors such as gear geometry, misalignment, and mounting tolerances play crucial roles in the vibrational and acoustic behavior of the system. This study investigates the effect of pinion mounting distance on NVH performance using a flexible multibody simulation approach.

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Methodology

Gear Design and Simulation:

  • The bevel gearset was modeled with detailed geometric and material properties, incorporating ease-off topography and misalignment parameters.
  • A flexible multibody dynamics (MBD) model was developed, combining the Craig-Bampton modal reduction technique and penalty contact formulation for accurate simulation of gear interactions.

Analysis Scope:

  • Various pinion offsets (± 0.1 mm, ± 0.5 mm) were tested under realistic operational loads.
  • Virtual accelerometers were placed on the E-Axle housing to measure vibrational responses.
  • Campbell diagrams and SPL calculations were used to assess dynamic behavior and acoustic performance.
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Results on NVH Behavior

  1. Vibration Analysis:

    • A negative pinion offset (-0.1 mm) reduced accelerations significantly compared to the neutral position, demonstrating improved vibrational stability.
    • Further negative offset (-0.5 mm) led to increased accelerations, indicating an optimal range for pinion adjustment.

  2. Acoustic Performance:

    • SPL analysis revealed a 2.0 dB reduction in noise levels at the optimal pinion offset.
    • Positive offsets increased both vibration amplitudes and SPL, underscoring the importance of precise mounting configurations.

  3. Validation:

    • Results align with practical observations, where pinion offset is often optimized experimentally to minimize transmission error and noise.
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Discussion

This study highlights the critical role of mounting distance in the NVH performance of bevel gear systems. By leveraging advanced MBD techniques, engineers can simulate and optimize gear dynamics without relying solely on physical prototypes. The findings provide a framework for:

  • Reducing transmission errors through precise gear alignment.
  • Improving acoustic performance by mitigating critical resonances.

Conclusion

The simulation-driven approach used in this study effectively minimizes NVH issues in bevel gear E-Axles. By optimizing pinion mounting distance, significant reductions in vibration and noise were achieved, enhancing system performance and reliability. Future work will incorporate experimental validation to further refine the virtual test bench methodology.