Politecnico di Torino - Corso Duca degli Abruzzi, 24 - 10129 Torino, ITALY

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Electrohydrostatic system for clutch assisted actuation

actuatorsAutomotive systemsCar clutchesMechatronic devicesX-by-wire Systems


The invention regards an actuation system able to perform the disengagement of a clutch in ground vehicles with automatic gear shifting. This solution can attain elevated performance while ensuring energy consumption efficiency, reduced actuator envelope and simplicity in its layout.

Technical features

This invention exploits a hydrostatic transmission driven by an electric motor to yield a controlled actuation system.
The controlled angular displacement of the electric motor (1) is transmitted to a fixed-displacement gear pump (2) through a mechanical joint (3). This action yields a volumetric displacement inside a hydraulic circuit. Therefore, this volume of fluid acts on the piston of an actuator (4) to attain linear motion.
The proposed solution can integrate a valve (5) (e.g. an on/off valve or a proportional valve) to keep the clutch in a disengaged position. A further measure to guarantee safety consists in the inclusion of a pressure-relief valve (6).
The control of this actuator can be improved using a dedicated electronic control unit (7) and a sensor for the feedback of the linear position of the hydraulic actuator (8).

Possible Applications

  • Clutches for automotive systems with automatic gear shifting;
  • Clutches for industrial machinery;
  • Linear positioning systems.


  • High efficiency;
  • Improved performance;
  • Compactness;
  • Simplicity;
  • Low costs;
  • Robustness.