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Hydraulic Function, Overview

Fig 1: Identifying Hydraulic Function Overview
GLL107828Courtesy of VOLVO CARS CORPORATION
  1. Cam disc
  2. Rollers
  3. Pressure valves
  4. Pressure limiting valve
  5. Control valve cover
  6. Oil pressure and temperature sensor
  7. Differential Electronic Module (DEM)
  8. Control valve/axial solenoid
  9. Accumulator
  10. Oil strainer
  11. Electrical feed pump
  12. Oil filter
  13. Suction valves
  14. Piston pump
  15. Working piston
  16. Wet disc package
  17. Bearings
  18. Compression springs

Active On demand Coupling (AOC) can be explained as a hydraulic pump.

The basic pressure in the system is built up by the electrical feed pump. This way the axial pistons are pressurized with oil so that they are pressed against the cam disc via the rollers. The axial piston builds up a working pressure which is conducted to the working piston via the pressure valves. This pressure creates a fixed connection between the input and output shafts. The maximum pressure is limited by the pressure limiting valve. The difference in speed between the input and output shafts is proportional in accordance with the oil pressure to the axial pistons. A large difference in speed between the input and output shafts provides high oil pressure to the axial pistons. The same speed on the input and output shafts provides lower oil pressure to the axial pistons. The oil pressure on the clutch driven plates is controlled by the control valve. The axial solenoid controls the control valve. A closed control valve provides maximum pressure to the clutch driven plates, which provides maximum power transmission. An open control valve provides minimum pressure to the clutch driven plates, which provides a limited power transmission.

The accumulator maintains the basic pressure in the system. The oil filter keeps the oil free from dirt and small particles which can damage the system.