Device for reversing a blade of a runner unit
Embodiments of the present invention generally relate to a runner unit of a tidal power plant, and more particularly to a device for reversing a blade of the runner unit. The device according to the embodiments is lighter and more efficient with respect to known solutions which involve articulated mechanisms as it is based on a reversing servomotor including an annular piston which acts on the blade to be reversed.
1. A device for reversing a blade of a runner unit, the device comprising:
an annular lever fixed to a trunnion portion of the blade and rotatably mounted on the runner unit;
a main servomotor comprising a first piston cylinder adapted to reciprocate along a shaft of the runner unit and coupled to said annular lever so as to cause a first rotation of the blade until said first piston cylinder reaches a dead zone position, said annular lever comprising a pin eccentric with respect to an axis of rotation of said annular lever, said pin being hosted in a groove formed in said first piston cylinder;
a reversing servomotor including a second piston cylinder arranged to cause a further rotation of the blade from said dead zone position; and
a connecting rod having a first end connected to said second piston cylinder and a second end eccentrically fixed on said annular lever, wherein said second piston cylinder is annular-shaped and is arranged concentric with and surrounding said first piston cylinder, said first piston cylinder being received within second piston cylinder.
2. The device according to claim 1 , wherein said reversing servomotor is adapted to reciprocate along the shaft of the runner unit.
3. The device according to claim 1 , wherein said first end of said connecting rod has an eyelet arranged to cooperate with a pivot fixed on said second piston cylinder, wherein said eyelet is configured to establish a movement relative to said pivot during motion of said main servomotor.
4. The device according to claim 3 , wherein said pivot is located on an internal wall of said second piston cylinder.
5. The device according to claim 1 , wherein said reversing servomotor is oil-operated.
6. The device according to claim 1 , further comprising a nut arranged around said pin and within said groove.
7. The device according to claim 1 , wherein said main servomotor is oil-operated.
8. A system comprising:
a runner unit having a shaft and at least one blade rotatably mounted on the shaft; and
a device for reversing the blade, the device comprising:
an annular lever fixed to a trunnion portion of the blade and rotatably mounted on the runner unit;
a main servomotor comprising a first piston cylinder adapted to reciprocate along the shaft of the runner unit and coupled to said annular level to cause a first rotation of the blade until said first piston cylinder reaches a dead zone position, said annular lever comprising a pin eccentric with respect to an axis of rotation of said annular lever, said pin being hosted in a groove formed in said first piston cylinder;
a reversing servomotor including a second piston cylinder arranged to cause a further rotation of the blade from said dead zone position; and
a connecting rod having a first end connected to said second piston cylinder and a second end eccentrically fixed on said annular lever, wherein said second piston cylinder is annular-shaped and is arranged concentric with and surrounding said first piston cylinder, said first piston cylinder being received within second piston cylinder.
9. The system according to claim 8 , wherein said reversing servomotor is adapted to reciprocate along the shaft of the runner unit.
10. The system according to claim 8 , wherein said first end of said connecting rod has an eyelet arranged to cooperate with a pivot fixed on said second piston cylinder, wherein said eyelet is configured to establish a movement relative to said pivot during motion of said main servomotor.
11. The system according to claim 10 , wherein said pivot is located on an internal wall of said second piston cylinder.
12. The system according to claim 8 , wherein said reversing servomotor is oil-operated.