Rotary vacuum pump with a device for decoupling the driving motor

A rotary vacuum pump having a rotor and comprising, between the rotor and a driving motor, a control unit for operatively connecting the rotor to the motor only in periods in which the pump operation is required or desired, and for decoupling the pump from the motor in other periods, said control unit including

• a rotating member connectable to a motor output and arranged to be made integral for rotation with the pump rotor when the pump operation is required or desired, and to be disconnected from the rotor in the other periods;—a plurality of mechanical coupling elements, which are located between the rotating member and an element belonging to or integral for rotation with the pump rotor, and are arranged to take a coupling position in which they make the rotating member and the rotor integral for rotation, and a decoupling position in which they make the rotating member and the rotor independent of each other;
• actuating members hydraulically driven for mechanically actuating said coupling elements, which members are driven by said rotating member so as to take, in the periods where the pump is operating, a first position, in which the actuating members let said coupling elements freely displace in a direction depending on the rotation direction of the rotating member in order the coupling elements move to the coupling position, if the rotating member rotates in a direction required for the pump operation, or to the decoupling position, if the rotating member rotates in a direction opposed to the direction required for the pump operation, and so as to take, in the periods where the pump is not operating, a second position, in which said actuating members bring said coupling elements to the decoupling position;
• and in that the pump further includes:
• means for supplying liquid for the hydraulic drive of the actuating members, and wherein the rotating member defines, together with the actuating members, at least one chamber for containing said liquid, and wherein the supply means are arranged to supply with the liquid said at least one chamber when the actuating members are to be brought to or kept in their second position.