Sealing device for a rotating machine

1. A sealing device in a rotating machine having a housing for containing a fluid; a shaft rotatable with respect to the housing, the sealing device being provided between the shaft and the housing, said sealing device comprising:

a first labyrinth arranged between the shaft and the housing,

fins arranged in the first labyrinth,

a second labyrinth arranged between the shaft and the housing,

a cavity arranged between the first labyrinth and the second labyrinth, and

a duct having a first opening upward toward the inside of the housing and a second opening connected to the cavity for allowing air inside the housing to enter the cavity,

wherein

the first labyrinth includes a moving wall secured to the shaft and a fixed wall secured to the housing, and an annular clearance provided between the moving wall and the fixed wall,

said fins are directly secured to the moving wall for discharging the fluid entering the first labyrinth toward an inside of the housing, and

said fins and the annular clearance form a centrifugal pump.

2. The device as claimed in claim 1 , wherein the fixed wall of the first labyrinth comprises an orifice adjacent to one of the fins for discharging the fluid.

3. The device as claimed in claim 2 , wherein said orifice of the fixed wall opens between the annular clearance and the inside of the housing.

4. The device as claimed in claim 3 , wherein the orifice is arranged in an upper part of the rotating machine above a level of the fluid when the shaft is in a horizontal position and the rotating machine is subject to no acceleration.

5. The device as claimed in claim 2 , wherein the orifice passes through the fixed wall of the first labyrinth along an axial direction of the shaft.

6. The device as claimed in claim 1 , wherein, in a flow path of the fluid, the second labyrinth has a pressure drop greater than that of the cavity.

7. The device as claimed in claim 1 , wherein the fluid comprises oil.

8. The device as claimed in claim 1 , wherein the rotating machine is an electric machine.

9. The device as claimed in claim 1 , further comprising a baffle arranged between the housing and the shaft and situated downstream of the first labyrinth in a flow path of the fluid for preventing particles, which are presented in the air and surrounding the rotating machine, from entering the housing.

10. The device as claimed in claim 9 , wherein the baffle comprises a channel between the fixing wall of the first labyrinth and the shaft, and the channel connecting the annular clearance.

11. The device as claimed in claim 1 , wherein the fins are bar-shaped and spaced away from each other.

12. The device as claimed in claim 1 , wherein each of the fins extends along the moving wall and radially outwardly from the shaft.

13. The device as claimed in claim 1 , wherein

the first labyrinth further comprises a first ring continuously extending between the annular clearance and the cavity, and a second ring connecting with the annular clearance,

the fixed wall includes a first portion and a second portion,

the first ring is arranged between the first portion and the moving wall, and the second ring is arranged between the second portion and the moving wall, and

the fins are arranged in the second ring and facing toward the second portion of the fixed wall.

14. The device as claimed in claim 1 , wherein the second labyrinth comprises a moving wall secured to the shaft and a fixed wall secured to the housing, and a ring provided between the moving wall and the fixed wall.

15. The device as claimed in claim 14 , wherein the cavity connects with the ring of the second labyrinth and the annular clearance of the first labyrinth.

16. The device as claimed in claim 1 , wherein the moving wall of the first labyrinth is a disk, and the fins are directly secured to the disk.