VR Pulley

vr-pulley for BISG applications

Intended for use with B-ISG and full Hybrid powertrains, IP has produced a new multi-mode crankshaft mounted VR-pulley technology. This largely passive device which packages within the standard pulley diameter provides all normal pulley functions including a crankshaft torsional damper. The VR-pulley gives the following functions and benefits.


  • B-ISG for gasoline and diesel passenger car engines
  • B-ISG for heavy-duty engines
  • Improved hybrid regenerative braking
  • Simplification of hybrid powertrains through integrated electric ancillary mode


  • In normal operation the drive to the pulley is via a one-way mechanism, as with many conventional de-coupler alternator drives. By engaging a simple clutch with a low power solenoid, the drive is transmitted via an epicyclic mechanism containing only simple spur gears creating a ratio that can be tuned to suit specific applications.
  • If the clutch is left open whilst the engine is stationary, the pulley is de-coupled from the crankshaft enabling the electrical machine to drive FEAD ancillaries through the belt.


  • Up to 3.5 x reduced electrical machine torque requirement for engine cranking
  • Verified 2.2 litre Diesel engine start at -30C
  • Major reduction in belt tension requirement
  • De-coupler function to improve dynamics and prevent belt squeal
  • Ancillary drive mode enabling electrical machine to drive engine ancillaries e.g. A/C compressor, water pump, vac pump etc., whilst engine is stopped
  • Re-optimised electrical machine can provide increased regeneration power in comparison to conventional B-ISG machines