Underwater vehicle comprising a propulsion chain and associated method

The present invention relates to a kinematic chain of an underwater vehicle. The invention also relates to an underwater vehicle and a method of dismantling such a kinematic chain.

The invention relates to the field of underwater vehicles and more particularly to the field of underwater propulsion.

It is known underwater vehicles comprising an outer shell and a sealed shell surrounded by the outer shell. The sealed hull comprises a rear partition forming a barrier between an immersed medium, accessible for a fluid coming from an exterior of the underwater vehicle, and an internal medium of the sealed hull, not accessible to the fluid.

Such submarines include propulsion kinematic chains comprising a propeller connected to a rotating drive shaft which is driven by a motor disposed inside the sealed hull. The drive shaft is in rotary contact with a submerged bearing supported by the outer shell, with another submerged bearing supported by the aft bulkhead and a carrier bearing disposed within the sealed shell. The propulsive forces between the drive shaft and the sealed hull come from the propeller and are transferred by the carrier bearing which includes a main stop. The supporting bearing, the main thrust bearing and the engine are fixed to the watertight hull cabins, which are welded in a lower part of a propulsion compartment in the watertight hull.

However, during the submersion of the underwater vehicle, the waterproof hull deforms. The elements of the propulsion chain then move relatively with respect to each other. For example, the carrier bearing, the main thrust bearing and the motor move vertically during compression of the sealed shell. Consequently, the propulsion chain is off-center relative to an axis of rotation of the propeller because of these deformations. Certain elements, in particular those of the propulsion chain, receive overloads. Overloads lead to rapid aging of these elements. In addition, the decentering of the propulsion chain results in a high noise emission from the chain and causes seawater to leak into the sealed hull.

There is therefore a need for an underwater vehicle exhibiting improved behavior during immersion and exhibiting better acoustic discretion.

For this, the present description relates to an underwater vehicle comprising an outer hull and a sealed hull surrounded by the outer hull, the hull

watertight delimiting a watertight space of the underwater vehicle, the watertight hull comprising a supporting structure delimiting an opening,

the underwater vehicle further comprising a propulsion chain comprising:

- a drive motor,

a drive shaft driven by the drive motor, the drive shaft extending in a longitudinal direction and passing through the opening,

- a propeller rigidly fixed to the drive shaft, and

- at least one front bearing in rolling contact with the drive shaft, the front bearing being rigidly fixed to the supporting structure, the front bearing being configured to transmit longitudinal forces between the drive shaft and the supporting structure .

According to particular embodiments, the underwater vehicle comprises one or more of the following characteristics, taken in isolation or in any technically possible combination:

the front bearing comprises a sealing device configured to prevent circulation of a fluid between the sealed space and an immersed space outside the sealed hull;

- the engine is rigidly fixed to the supporting structure;

a motor shaft is connected to the drive shaft via a junction, the junction being elastically deformable at least in the longitudinal direction;

- The front bearing comprises a plurality of bearings, each bearing comprising rollers, each roller being configured to rotate about an axis of rotation, the axis of rotation of a roller of the bearing being inclined relative to the axis of rotation of another roller of the bearing;

- the front bearing comprises a sealing device configured to prevent circulation of a fluid between the sealed space and an immersed space outside the sealed hull, and the sealing device and the plurality of bearings are spaced apart between them by a distance of less than 200 millimeters in the longitudinal direction, preferably less than 100 millimeters;

- The front bearing is further configured to transmit transverse forces, the transverse forces being perpendicular to the longitudinal forces;

- the underwater vehicle comprises a rear bearing fixed to the outer hull, the rear bearing being in rolling contact with the drive shaft; and

- The supporting structure comprises a coaming projecting from a rear surface of the supporting structure.

The present description also relates to a method of dismantling the propulsion chain of an underwater vehicle comprising an outer hull and a sealed hull surrounded by the outer hull, the sealed hull delimiting a sealed space of the underwater vehicle, the waterproof shell comprising a supporting structure delimiting an opening,

the underwater vehicle further comprising a propulsion chain comprising:

- a drive motor,

a drive shaft driven by the drive motor, the drive shaft extending in a longitudinal direction and passing through the opening,

- a propeller rigidly fixed to the drive shaft, and

- at least one front bearing in rolling contact with the drive shaft, the front bearing being rigidly fixed to the supporting structure, the front bearing being configured to transmit longitudinal forces between the drive shaft and the supporting structure , the method comprising:

- the sliding of the propeller in the longitudinal direction towards the outside of the underwater vehicle,

- sliding of the rear bearing towards the outside of the underwater vehicle, and

- the sliding at least of the drive shaft and the front bearing outwards.

Other characteristics and advantages of the invention will become apparent on reading the following description of embodiments of the invention, given by way of example only and with reference to the drawings which are:

- Figure 1, a schematic view of part of a submarine comprising a propulsion chain, and

- Figure 2, a schematic view of part of the submarine showing forces present during propulsion of the underwater vehicle.

A part of an underwater vehicle 10 is shown in Figure 1. The underwater vehicle 10 is intended to be in an underwater environment, for example seawater. In the following, the underwater vehicle -marine 10 and simply referred to as submarine 10.

The submarine 10 comprises an outer hull 20, a watertight hull 22 and a propulsion chain 26.

A longitudinal direction L is defined for the submarine 10. The longitudinal direction L is the direction in which a propulsive force of the propulsion chain 26 is intended to be produced.

In the remainder of the description, the expressions “transversely” and “transverse” denote any direction perpendicular to the longitudinal direction L.

The outer shell 20 forms an outer structure of the submarine 10 delimiting an inner space 27. The outer shell 20 is intended to be in direct contact with the underwater environment.

The interior space 27 comprises a submerged space 28 and a sealed space 29. The submerged space 28 is delimited by an interior surface of the exterior shell 20 and an exterior surface of the waterproof shell 22. The sea water circulates in it. 'submerged space 28.

The outer shell 20 comprises a rear frame 30, corresponding to the rear end of the outer shell 20. The rear frame 30 comprises axisymmetric structures.

The waterproof hull 22 is located in the interior space 27. The waterproof hull 22 is an axisymmetric structure delimiting a waterproof space 29 of the submarine 10. For example, the crew and navigation instruments of the submarine 10 are located in the sealed space 29. The sealed space 29 is waterproof with respect to the exterior of the submarine 10.

The waterproof shell 22 comprises a rear bulkhead 31 and a supporting structure 32.

The rear partition 31 is a wall at the rear of the watertight hull 22 defining a hole 33.

The supporting structure 32 is a structure comprising a rear surface 42. The supporting structure 32 is rigidly fixed to the rear partition 31. For example, the supporting structure 32 is bolted to the rear partition 31.

The supporting structure 32 is the rear end of the waterproof shell 22.

The supporting structure 32 defines an opening 36. The opening 36 is configured to receive a portion of the propulsion chain 26.

The supporting structure 32 comprises a coaming 40. The coaming 40 is a structure projecting from the rear surface 42 of the supporting structure 32 in the longitudinal direction L.

The supporting structure 32 is rigidly fixed to the waterproof shell 22. For example, the supporting structure 32 is fixed by screws 38 to the waterproof shell 22 as shown in FIG. 1. A possible spacing between the sealed shell 22 and the supporting structure 32 is, for example, blocked by a sealing mass, not shown.

The supporting structure 32 is able to transmit forces between the sealed hull 22 and the propulsion chain 26.

The propulsion chain 26 is configured to generate a force for propelling the submarine 10.

The propulsion chain 26 includes a propeller 50, a drive shaft 52, a drive motor 54, a junction 56, a rear bearing 58, and a front bearing 59.

The propeller 50 comprises a circular crown 60 and a plurality of blades 61 fixed to the crown 60. The propeller 50 is configured to rotate about an axis of rotation R and to generate a propulsive force in the longitudinal direction L.

The axis of rotation R is parallel to the longitudinal direction L. The axis of rotation R is defined as the axis around which the drive shaft 52 is intended to rotate relative to the sealed hull 22 of the submarine. 10.

The drive shaft 52 is a propeller shaft connected to the propeller 50. The drive shaft 52 is, for example, a cylindrical shaft with a circular base extending in the direction of the cylinder. The circular base has, for example, a radius of between 30 millimeters (mm) and 200 mm, preferably between 80 mm and 120 mm. The drive shaft 52 extends between a rear end 62 and a front end 63 in the longitudinal direction L. The rear end 62 of the drive shaft 52 is rigidly fixed to the propeller 50. L ' front end 63 of drive shaft 52 is attached to junction 56.

The drive shaft 52 passes through the supporting structure 32, through the opening 36.

The motor 54 is, for example, an electric motor. The motor 54 comprises a stator and a rotor configured to rotate about the axis of rotation R. The rotor is fixed to a motor shaft 64.

The motor 54 is rigidly fixed to the supporting structure 32. The stator of the motor 54 is rigidly fixed to a fixing 65. The fixing 65 is fixed to the supporting structure 32. The motor 54 is centered on the axis of rotation R.

The junction 56 is an elastic coupling between the drive shaft 52 and the drive shaft 64.

The junction 56 comprises, for example, a ball received by two mechanical blocks respectively fixed to the drive shaft 52 and to the motor shaft 64. The ball is lubricated. The junction 56 is configured to tolerate rotations of the drive shaft 52 and the drive shaft 64 around the ball joint. Further, junction 56 is configured to accommodate movement of drive shaft 52 relative to drive shaft 64.

The distance between the ball joint and each mechanical block is variable. The junction 56 is, for example, elastically deformable in the longitudinal direction L and / or transversely.

As a variant, the junction 56 comprises a double ball joint. Such a double ball joint comprises two ball joints forming a gimbal suspension.

The rear bearing 58 is a bearing submerged in sea water. The rear bearing 58 is configured to be cooled by sea water.

The rear bearing 58 is fixed to a metal structure 66. The metal structure 66 is a bearing chair fixed by screws to the outer shell 20. The metal structure 66 is fixed to the rear frame 30 of the outer shell 20. For example , the metal structure 66 is bolted to the rear frame 30. The metal structure 66 is removable.

The rear bearing 58 is intended to be in rolling contact with the drive shaft 52.

By the expression "rolling contact" is meant a lubricated connection between two elements configured to rotate relative to one another.

The rear bearing 58 is configured to transmit forces between the drive shaft 52 and the outer shell 20. For example, the rear bearing 58 is configured to transmit propulsive forces.

The front bearing 59 is a sealed bearing. The front bearing 59 is fixed to the supporting structure 32. The front bearing 59 is intended to be in rolling contact with the drive shaft 52. The front bearing 59 is centered on the supporting structure 32, with respect to the axis of rotation R.

The front bearing 59 is intended to transmit forces between the supporting structure 32 and the drive shaft 52.

The front bearing 59 is configured to transmit longitudinal forces and transverse forces.

For example, the front bearing 59 is configured to transmit thrust forces in the longitudinal direction L. The front bearing 59 is, moreover, a carrier bearing intended to support the weight of the drive shaft 52.

Preferably, the front bearing 59 forms a main stop configured to transmit the majority of the longitudinal forces.

The expression “majority of the forces” is understood to mean more than 50% of the corresponding forces, and preferably at least 75% of the corresponding forces.

Advantageously, the front bearing 59 is configured to transmit all of the longitudinal forces.

The front bearing 59 includes a housing 70, a seal, and a plurality of bearings.

The housing 70 is a metal housing housing the sealing device and the plurality of bearings. The housing 70 is centered and bolted to the supporting structure 32.

The sealing device is a lip seal. The sealing device comprises a first mechanical seal attached to the drive shaft 52 and a second seal is attached to the front bearing housing 59.

The first seal is supported on the second seal by springs fixed on the drive shaft 52 and disposed in the submerged space 28.

The sealing device further comprises a drip box, configured to recover any leakage of seawater passing between the first seal and the second seal. The drip box is located in the sealed space 29, inside the sealed shell 22.

The first gasket and the second gasket are in sliding contact with each other.

By the expression “sliding contact”, it is understood that the linings are in physical contact with one another and that the first lining is able to rotate with respect to the second lining.

The sealing device forms a fluid barrier between the interior space 27 and the sealed space 29. In other words, the sealing device is configured to prevent a flow of a fluid between the interior space 27 and the outside of the waterproof shell 22.

The sealing device is configured to be cooled by direct heat exchange with sea water circulating in the submerged space 28 between the sealed hull 22 and the outer hull 20.

Each bearing of the plurality of bearings is greased and configured to work in a sealed environment. Each bearing is centered with respect to the axis of rotation R.

Each bearing includes rings and rollers. Each roller is configured to rotate around an axis of rotation. The axis of rotation of one roller of the bearing is inclined relative to the axis of rotation of another roller of the bearing. Two rollers are respectively arranged in a conical manner.

Preferably, the sealing device is placed very close to the bearings in the longitudinal direction L. For example, the sealing device and the plurality of bearings are spaced from each other by a distance of less than 200 millimeters in the longitudinal direction L , preferably less than 100 millimeters.

The operation of the submarine 10 is now described. In particular, the propulsion of the submarine 10 by the propulsion chain 26 is described.

The motor 54 turns the rotor and the motor shaft 64 about the axis of rotation R. Through the junction 56, the drive shaft 52 and the propeller 50 are actuated.

In Figure 2, forces present on the propulsion chain 26 during propulsion are schematically shown.

On the rear bearing 58, transverse forces A1 are applied during propulsion. The rear bearing 58 transmits only transverse forces between the propulsion chain 26 and the outer shell 20. The rear bearing 58 does not transmit longitudinal forces.

On the front bearing 59, transverse forces A2 and longitudinal forces B are applied.

The transverse forces A1, A2 are perpendicular to the longitudinal forces B.

The rotation of the propeller 50 generates a thrust in the longitudinal direction L which causes a displacement of the submarine 10. The longitudinal forces B are in particular thrust forces.

The front bearing 59 transmits transverse forces and longitudinal forces between the propulsion chain 26 and the sealed hull 22. In the example shown in FIG. 2, all of the longitudinal forces between the sealed hull 22 and the shaft d drive 52 is transmitted by the front bearing 59.

The rear bearing 58 forms a rear support and the front bearing 59 forms a front support for the propulsion chain 26. In the example shown, the front support and the rear support are the only supports between the propulsion chain 26 d. 'on the one hand and the outer shell 20 and the waterproof shell 22 on the other hand.

The propulsion chain 26 thus forms an isostatic system.

Due to this isostatic character, the submarine 10 as described has a number of advantages.

As the sealing device and the bearings are arranged in the housing 70, the propulsion chain 26 is particularly compact. In addition, the length of the propulsion chain 26 in the longitudinal direction L is reduced. As a result, more space is available in the waterproof shell 22.

Unlike the state of the art, in which the engine is carried by cabins in the sealed hull, the engine 54 of FIG. 1 is carried by the supporting structure 32. During the submersion of the submarine 10, the 22 waterproof hull and hull

outer 20 are deformed transversely. The motor 54 remains, during a deformation of the sealed shell 22 in immersion, centered on the axis of rotation R and centered with respect to the front bearing 59.

In the submarine 10, the propulsion chain 26 remains centered relative to a central axis, the sealed hull 22 at any depth.

As the front bearing 59 remains centered relative to the axis of rotation R, the mechanical load on the front bearing 59 is reduced. As a result, the submarine 10 exhibits improved acoustic discretion. In addition, the front bearing 59 has an increased service life.

The fact that the longitudinal and transverse forces are mainly transferred by the front bearing 59 thus makes it possible to avoid a decentering of the drive shaft 52 during a deformation of the sealed shell 22 or of the outer shell 20 in immersion of the submarine 10.

A transverse displacement of a support does not cause an offset of the front bearing 59 or of the rear bearing 58.

As the motor 54 is fixed to the supporting structure 32, the relative displacement between the motor 54 and the front bearing 59, also fixed to the supporting structure 32, is reduced. Consequently, the propulsion chain 26 is less sensitive to the contractions of the sealed hull 22.

In addition, as the sealing device is placed very close to the bearings, during a deformation of the sealed shell 22 in immersion, the first seal moves very little relative to the second seal of the sealing device. As a result, the sealing device is less tired and has a longer service life.

For example, the sealing device and the plurality of bearings are spaced from each other by a distance of less than 200 millimeters in the longitudinal direction L, preferably less than 100 millimeters.

As the sealer is cooled by direct heat exchange with seawater, no water pump is required to cool the sealer.

Furthermore, the propulsion chain 26 is simplified, in particular because the front bearing 59 includes the sealing device and bearings forming a thrust bearing and a bearing. In addition, the cumbersome cabins supporting the engine in the state of the art are eliminated, which makes it possible to save space in the sealed hull 22. In addition, the cabin supporting the main stop is eliminated, this cabin being in. practice difficult to stiffen.

The assembly and disassembly of the propulsion chain 26 is made simpler. In particular, the submarine 10 allows assembly or disassembly of the propulsion chain 26 from the rear of the submarine 10. Consequently, in particular maintenance is simplified.

To illustrate such simplicity, a method of dismantling the propulsion chain 26 is now described.

During the dismantling process, the propulsion chain 26 is removed from a stern, the aft end of the submarine 10, towards the rear.

During a first step, the propeller 50 is unscrewed and slid backwards. The propeller is slid in the longitudinal direction L towards the outside of the underwater vehicle 10. During a second step, the rear bearing 58 is slid towards the rear, towards the outside of the underwater vehicle 10. During a third step, the drive shaft 52, the front bearing 59 and the junction 56 are slid backwards, towards the outside of the underwater vehicle 10.

Then, the supporting structure 32 is unscrewed from the sealed shell 22 and the supporting structure 32, the fixing 65 and the motor 54 are removed towards the rear.

At the end of the dismantling process, the entire propulsion chain 26 is dismantled towards the rear of the submarine 10.

A method of mounting the propulsion chain 26 is now described.

First, the motor 54 and the attachment 65 are introduced into the sealed space 29 by the stern. The supporting structure 32 is fixed to the fixing 65 and the supporting structure 32 is screwed to the waterproof shell 22.

Then, the junction 56, the drive shaft 52 and the front bearing 59 are introduced through the stern. The front bearing 59 is fixed to the supporting structure 32 and the junction 56 is connected to the motor shaft 64. In the next mounting step, the rear bearing 58 is mounted on the drive shaft 52. In the process of the following assembly step, the propeller 50 is screwed to the drive shaft 52.

As the propulsion chain 26 can be assembled outside the submarine 10, this makes it possible to pre-assemble or test the propulsion chain 26 in the workshop, independently of assembly of the submarine 10.

Furthermore, the assembly and disassembly method makes it possible to easily replace the propulsion chain 26 in order to adapt, for example, to the operational needs of the submarine 10 or to replace a faulty propulsion chain chain 26. In addition, the accessibility for maintenance of the propulsion chain 26 is improved.
CLAIMS

1.- Underwater vehicle (10) comprising an outer hull (20) and a sealed hull (22) surrounded by the outer hull (20), the sealed hull (22) defining a sealed space (29) of the underwater vehicle marine (10), the waterproof hull (22) comprising a supporting structure (32) delimiting an opening (36),

the underwater vehicle (10) further comprising a propulsion chain (26) comprising:

- a drive motor (54),

- a drive shaft (52) driven by the drive motor (54), the drive shaft (52) extending in a longitudinal direction (L) and passing through the opening (36),

- a propeller (50) rigidly fixed to the drive shaft (52), and

- at least one front bearing (59) in rolling contact with the drive shaft (52), the front bearing (59) being rigidly fixed to the supporting structure (32), the front bearing (59) being configured to transmitting longitudinal forces between the drive shaft (52) and the supporting structure (32).

2. An underwater vehicle according to claim 1, wherein the front bearing (59) comprises a sealing device configured to prevent circulation of a fluid between the sealed space (29) and an immersed space (28). outside the waterproof shell (22).

3. An underwater vehicle according to claim 1 or 2, wherein the motor (54) is rigidly fixed to the supporting structure (32).

4.- Underwater vehicle according to any one of claims 1 to 3, wherein a drive shaft (64) is connected to the drive shaft (52) via a junction (56), the junction (56) being elastically deformable at least in the longitudinal direction (L).

5. A submarine vehicle according to any one of claims 1 to 4, wherein the front bearing (59) comprises a plurality of bearings, each bearing comprising rollers, each roller being configured to rotate about an axis of rotation, the axis of rotation of one roller of the bearing being inclined relative to the axis of rotation of another roller of the bearing.

6. An underwater vehicle according to claim 5, wherein the front bearing (59) comprises a sealing device configured to prevent a flow of a fluid between the sealed space (29) and a submerged space (28). outside the sealed shell (22), and in which the sealing device and the plurality of bearings are spaced from each other by a distance of less than 200 millimeters in the longitudinal direction (L), preferably less than 100 millimeters.

7. An underwater vehicle according to any one of claims 1 to 6, wherein the front bearing (59) is further configured to transmit transverse forces, the transverse forces being perpendicular to the longitudinal forces.

8. An underwater vehicle according to any one of claims 1 to 7, wherein the underwater vehicle (10) comprises a rear bearing (58) fixed to the outer hull (20), the rear bearing (58) being in rolling contact with the drive shaft (52).

9. An underwater vehicle according to any one of claims 1 to 8, wherein the supporting structure (32) comprises a coaming (40) projecting from a rear surface (42) of the supporting structure (32).

10.- A method of dismantling the propulsion chain (26) of an underwater vehicle (10) comprising an outer shell (20) and a sealed hull (22) surrounded by the outer hull (20), the sealed hull (22) delimiting a sealed space (29) of the underwater vehicle (10), the sealed hull (22) comprising a supporting structure (32) delimiting an opening (36),

the underwater vehicle (10) further comprising a propulsion chain (26) comprising:

- a drive motor (54),

- a drive shaft (52) driven by the drive motor (54), the drive shaft (52) extending in a longitudinal direction (L) and passing through the opening (36),

- a propeller (50) rigidly fixed to the drive shaft (52), and

- at least one front bearing (59) in rolling contact with the drive shaft (52), the front bearing (59) being rigidly fixed to the supporting structure (32), the front bearing (59) being configured to transmitting longitudinal forces between the drive shaft (52) and the supporting structure (32), the method comprising:

- the sliding of the propeller (50) in the longitudinal direction (L) towards the outside of the underwater vehicle (10),

- sliding of the rear bearing (58) towards the outside of the underwater vehicle (10),

- the sliding at least of the drive shaft (52) and of the front bearing (59) outwards.