Noise Vibration Harshness development of transmission and drivetrains

Drivetrain Noise Vibration Harshness (NVH) Test System

The increasing complexity of modern powertrains is placing increasing demands on the Instrumentation and Test Systems. The downsizing of modern combustion engines is a challenge for Sound Engineering (Reduction of interior and exterior noise). Parallel development activities of key powertrain components (combustion engine, hybrid engine, transmission, etc.) require transmission and drivetrain testing activities at the earliest possible stage. The acoustic survey of the drivetrain outside the chassis as well as the torsional analysis is a must. The Test System must be flexible to develop various transmission types:

  • Manual Transmission (MT)
  • Automatic Transmissions (AT)
  • CVT-Transmission
  • Automated Manual Transmissions (AMT)
  • Double Clutch Transmissions (DCT)
  • Transmissions for Hybrid Electrical Vehicles (HEV)

AVL Approach

The success of NVH testing of modern and complex powertrains is defined by the acoustic behavior of the complete test cell.

AVL's Test System involves:

  • The load dynamometers are placed outside the test room
  • Low noise shaft bearings are used
  • Sound tight wall penetration is mandatory
  • Stiff shaft bearing supports with low distortion of the unit under test sound propagation is used
  • Big silencers are used to prevent fan noise

Benefits at a Glance

  • Airborne Noise Measurement
  • Farfield Measurement: total overview of noise radiation
  • Nearfield noise measurement: single component noise detection
  • Acoustic holography: noise source mapping
  • Sound intensity measurement: sound power radiation, sound power ranking of noise sources
  • Torsional Vibration Analysis
  • Torsional vibration excitation of transmission, clutch and coupling shafts using a primemover