Front enclosure which is sealed during the modular dismantling of a turbojet with reduction gear

1. A bypass turbojet engine comprising:

a fan driven by a fan shaft supported by at least two first bearings each having a rotating ring and a fixed ring,

a turbine shaft supported by a second bearing having a fixed ring and a rotating ring,

said turbine shaft driving said fan shaft through a rotational speed reducer, said rotational speed reducer and said first and second bearings being received in a lubrication vessel,

said lubrication vessel forming a ring that is coaxial with the turbine shaft, and comprising a casing having fixed portions and movable portions, said fixed and movable portions being interconnected by first, second and third seals,

said rotational speed reducer having an input wheel shaped so as to receive the torque transmitted, through drive means, by said turbine shaft,

wherein said movable portions of the casing comprise, from upstream to downstream:

said fan shaft extending from said first seal and carrying the rotating ring of each of said at least two first bearings,

a downstream extension casing extending between said fan shaft and said second seal,

said drive means extending between said second seal and said rotating ring of the second bearing, said drive means comprising a drive ring engaged with said input wheel and an intermediate drive shaft carrying said rotating ring of the second bearing, and

a downstream end of the intermediate drive shaft connected to said third seal.

2. The turbojet engine according to claim 1 , wherein a first end portion of the intermediate drive shaft is positioned radially between said rotating ring of the second bearing and said upstream end of the turbine shaft, and wherein a second, opposite end portion of the intermediate drive shaft supports the third seal.

3. The turbojet engine according to claim 1 , wherein the intermediate drive shaft and the drive ring are coaxial with said turbine shaft.

4. The turbojet engine according to claim 3 , wherein an O-ring is disposed between a downstream portion of the drive ring and a corresponding radial face of the intermediate drive shaft.

5. The turbojet engine according to claim 3 , wherein said intermediate drive shaft comprises a portion which is shaped so as to cooperate with the turbine shaft and receive the torque to be transmitted to the rotational speed reducer, said portion being positioned between said rotating ring of the second bearing and said turbine shaft.

6. The turbojet engine according to claim 5 , further comprising, axially in the region of said second bearing, a journal supporting a rotor of the turbojet engine, wherein said portion of the intermediate drive shaft is positioned between said rotating ring of the second bearing and said journal.

7. The turbojet engine according to claim 1 , wherein said first and third seals are of a rotor/stator type and are positioned in the region of one of the at least two first bearings and the second bearing respectively, and wherein said second seal is of the rotor/rotor type and is positioned lengthwise between said turbine shaft and said fan shaft.

8. The turbojet engine according to claim 7 , wherein said second seal is configured to be supported, firstly, by the downstream extension casing of said fan shaft and, secondly, by said drive ring.

9. The turbojet engine according to claim 7 , wherein said second seal comprises a movable labyrinth seal.

10. The turbojet engine according to claim 1 , wherein the internal diameter of each of the elements of the movable portions of said lubrication vessel is greater than that of the turbine shaft.

11. The turbojet engine according to claim 1 , wherein a clutch formed by a series of circumferentially extending teeth is positioned inside the drive ring.

12. The turbojet engine according to claim 1 , wherein the drive ring is retained axially in support against the rotational speed reducer by an axial retainer ring.