Figure: Measurements on the auxiliary units

Measurements on the auxiliary units

Problem: Slippage, belt vibrations, premature wear of the belt drive components

Goal: Precise design of the auxiliary units

Auxiliary drives such as the power steering pump or the air-conditioning compressor, which regulates the temperature in the vehicle, provide a high level of driving comfort. To prevent damage, correct belt tension must be ensured in the auxiliary drives at all times. If the tension is too low, this leads to slippage and belt vibrations and thus to premature wear of the belt drive components.

The functional tests on auxiliary drives (FEAD) and belt-starter-generator drives (BAS) comprise the measurement and evaluation of the slip and dynamic behavior of the entire belt drive system.
In figure above, the belt forces, tensioner movements and belt vibrations are important measured variables in addition to the high-resolution measurement of the rotational angle position of the crankshaft and all other belt pulleys. In addition, the operating state of the engine and the load conditions of the auxiliary units as well as the current torque of the BAS generator have a significant influence on the drive behavior. The evaluation is performed in time and spectral domain.

In hybrid drives, the state of charge of the battery plays a significant role. Here, most of the variables are available with sufficient resolution on the CAN BUS and can be recorded using the ROTEC CAN BUS board.
In BAS systems, the starting and stopping processes of the engine as well as the switching of the starter generator between engine and generator operation (recuperation) represent one of the most difficult dynamic states, which is why sensor technology with detection of the direction of rotation is required to record the correct speed ratios. For this task ROTEC provides appropriate sensor solutions such as encoder adaptation modules or quadruple sensors.

The recorded measured values are evaluated in the time and spectral domain.

Furthermore ROTEC ENGINEERING provides you with support and technical engineering know-how for problems related to vibration analysis of engines, transmissions and drive trains. With our know-how, we make a valuable contribution to your product in the areas of timing gear validation, valve train optimization, clutch design, transmission errors (TE), transmission optimization, oil supply optimization, powertrain measurement and optimization, current and voltage analysis, and the application of measurement technology.

Time domain analyses

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  • Belt loads
  • Bearing forces
  • Tensioner preload and damping forces
  • Force vector calculation depending on the tensioner position
  • Slip behavior in the overall transmission
  • Start and stop behavior
  • Speed gradient and peak torque evaluations

Spectral domain analyses

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  • Analysis of dynamic excitations
  • Verification of vibration dampers and coupling systems
  • Resonance behavior of the overall system
  • Change of natural frequencies over ambient condition
  • Dynamic peak loads

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