TURBINE FOR AN AIRCRAFT WITH A CENTERING AUTOMATIC ACTIVATED

1. Technical Field of the Invention

The invention relates to turbine engines for aircraft, particularly turbine engines comprising a free turbine of which a level is offset in a reduction gearbox.

2. BACKGROUND

A gas turbine engine comprises in known manner a gas generator and a free turbine mounted on a shaft, said power shaft. This power shaft is configured to be mechanically connected to a gearbox housing. The gear housing is, for example, in the case of a helicopter, a power transmission box connected to the (x) rotor (s) of the helicopter. When the power of the free turbine shaft and the gear housing are mechanically coupled, the power of the power shaft is transmitted to the power transmission box, thereby rotating the (s) rotor ( s) of the helicopter.

The free power turbine shaft is in turn driven in rotation by the free turbine which receives the gases produced by the gas generator and that relaxes, which allows to transform the kinetic energy of gas received in a power mechanically recovered by the power shaft.

The power shaft therefore comprises two ends, one end, said end of power, which is configured to be connected to the gearbox casing, and an opposite end, said free end, which typically carries the blades of the free turbine.

In addition, the current trend is to design directly built-in turbine gear boxes. Such turbine insert is configured to be directly connected to the gear housing and be maintained by the reduction gearbox. The mechanical connection between the power shaft and the gear box is then a flush connection. This recess may be a recess vertical, horizontal or oblique. This feature allows a significant weight saving on the overall drive train of the aircraft. Built a turbine engine has the added advantage of being dismantled without difficulty the gear box, eg for maintenance on the turbine engine.

In this context, it is planned to deport directly in the gear box bearings of the power end of the power shaft. This particular arrangement limits the axial length of the drive train formed by the engine and the gearbox housing. In addition, the connection between the engine and the gearbox is simplified by the removal of the transmission system: universal and system type "flectors" or "Bendix".

One of the technical problems that result of this arrangement of the bearing of the power end of the power shaft in the gear case is that the power shaft is no longer held by its power level when n is not embedded in the gear box. Therefore, in all situations where the turbine engine is not embedded in the gear housing - for example, during the transport of a turbine engine of a production site or a turbine engine maintenance to the installation site on the aircraft during storage of the turbine engine, etc. - there is a risk of deterioration of sealing systems and turbine engine bearings with radial deviation of the tree. For example, an eccentricity of the shaft can generate a degradation of a system dynamic type seal to carbon ring or lip seal. This lack of maintenance can also cause a rotor-stator contact in the case of a labyrinth seals powered by an air system, for example by a contact between a labyrinth tooth in radial contact with the non-latching power shaft .

3. Objectives of the invention

The invention aims to provide, in at least one embodiment of the invention, a turbine engine that overcomes at least some of the technical problems encountered by the turbine engine of the prior art.

The invention also aims to provide, in at least one embodiment of the invention, a gas turbine engine built in a gear box which is not susceptible to degradation of sealing systems and / or the turbine engine bearings, including when the turbine engine is mechanically separated from the

reduction gearbox.

The invention also aims to provide, in at least one embodiment, a built-in turbine engine which ensures maintaining the bearing of the end of power of the power shaft, even when the turbine engine is mechanically separated from the reduction gearbox.

The invention also aims to provide, in at least one embodiment, an aircraft, especially a helicopter, equipped with at least one turbine engine according to the invention.

4. Summary of the Invention

To do this, the invention relates to a gas turbine engine comprising a housing in which is arranged a gas generator and a free turbine mounted on a power shaft configured to be accoupléVdésaccouplé mechanically to a gearbox housing.

A turbine engine according to the invention is characterized in that it comprises at least one movable between a centering position, called the active position, in which it forms a bearing of said power shaft and corresponding to a mechanical uncoupling between said power shaft and said reducer housing, and a position, called the passive position, wherein it is spaced from said power shaft and corresponding to a mechanical coupling between said power shaft and said gearbox housing.

A turbine engine according to the invention is equipped with a mobile centering device adapted to be placed in an active position in which it forms a bearing of the power shaft, which allows self-holding the power shaft to the engine when separated from the gearbox housing. Further, when the power shaft is mechanically connected to the gear casing, the mobile centering device is in a passive position in which it is radially spaced from the power shaft so as to release the shaft from excessive strain.

A turbine engine according to the invention is therefore particularly for forming a turbine engine built in a gear box.

Such a turbine engine built thus comprises at least one movable centering between an active position wherein the centraliser forms a bearing of said power shaft when said turbine engine is separated from said reducer housing and corresponding to a mechanical uncoupling between said power shaft and said gear housing, and a passive position, wherein the centraliser is spaced from said power shaft when said turbine engine is recessed on said gearbox housing and corresponding to a mechanical coupling between said power shaft and said gearbox housing.

Also, in all situations where the turbine engine is not built on the gear limp - storage of the turbine engine disassembly / reassembly of the turbine engine, turbine-powered transport, etc. - the free power turbine shaft is held in position by the movable centering device, which then is in the active position and form a bearing of the power shaft.

In practice, the power shaft comprises at least one bearing near each of its ends. The end near the gear box is called power end and the other end is called the free end. The bearing of the free end is formed by a bearing housing on the housing of the turbine engine. The bearing of the power end is formed by the movable centering device in the active position. Once embedded in the gear housing, the bearing is directly formed by the gear case, which then replaces the bearing formed by the movable centering device in the active position.

Advantageously and according to the invention, at least one movable centering - preferably, each mobile centering - is configured to automatically switch from said active position to said inactive position upon mating of said shaft power to said gearbox housing and to pass automatically said passive position to said active position during uncoupling of said shaft power to said gearbox housing.

According to this advantageous variant, the transition from the passive position to the active position is automatic and concomitant mechanical separation between the gear housing and the power shaft and the passage from the active position to the passive position is automatic and concomitant to embedding the turbine engine to the gear box.

This passage from the active position to passive and vice versa being

automatic mounting / dismounting a gas turbine engine on a reduction gearbox requires less vigilance relative to a non-equipped mobile centering turbine engine. Indeed, the mobile centering means forming a bearing of the power shaft is automatically switched in place during disassembly of the turbine engine and the shaft centraliser releases automatically when the turbine engine is mounted on the gear housing. The operation of a turbine engine according to this variant of the invention is therefore particularly easy for an operator during the assembly / disassembly of the turbine engine.

Advantageously and according to the invention, at least one movable centering - preferably each mobile centering - comprises a tapered guide ramp having an axis parallel to the axis of said power shaft, and shaped to a conical portion of said housing so that the sliding said guide ramp on said conical portion of said housing moves radially centering said movable with respect to said power shaft.

According to this variant, the mobile centering device includes a tapered guide ramp formed in a tapered portion of the turbine engine casing. This guide ramp being of axis parallel to the axis of the power shaft, the slope of the ramp is inclined relative to the axis of the power shaft. Also, slippage of the centralizer on the conical portion of the housing causes a movement of the centraliser relative to the power shaft, from the active position to the passive position and vice versa, according to the direction of movement of the centraliser relative to the conical portion housing.

Advantageously, a gas turbine engine according to the invention comprises at least one spring mounted perpendicularly to said power shaft, between said housing and a movable centering device, and at least one axial spring extending between said housing and movable centering device, said springs being fixedly mounted relative to the housing and slidable relative to the movable centering device, and being configured to be able to exercise a resultant force which opposes the spontaneous sliding of said guide ramp on said conical portion of said housing toward said housing.

According to another variant, these springs are replaced by other equivalent elastic means.

According to yet another variant, the springs or resilient means are inclined with respect to the axis of the power shaft.

According to these variants, the springs (or equivalent elastic means) opposing the spontaneous sliding of the guide ramp on the tapered portion toward the housing. In other words, in the absence of an external constraint, the conical ramp of the centering device is not in contact with the tapered portion of the casing. In the absence of an external stress, the springs push the mobile centering device to the power shaft, so that it can form a bearing of the power shaft. The springs being slidable along the traveling centralizer mounted and fixed relative to the housing, each spring ensures the movement of the movable centering in a privileged direction without forcing the movement of the centraliser in the perpendicular direction.

Conversely, if an external force is exerted on the centering device in the direction of the housing, the cam track slides on the tapered portion of the casing and thus departs radially from the power shaft.

For this purpose, advantageously and according to the invention, a mobile centraliser has a stop extending in a plane perpendicular to the axis of said power shaft opposite a bearing surface of the gear housing so that the coupling mechanical power between said shaft and said reducer housing generates a mechanical contact between said bearing surface and said abutment which causes, by compression of said springs, said sliding centering on said conical portion of said housing of said active position in which it forms a bearing of the power shaft to said passive position in which it is spaced from one shaft.

According to this variant, the contact between the bearing surface of the gear housing and the abutment of the mobile centering resulting from the installation of the turbine engine to the gear unit housing, automatically causes slippage of the centralizer on the conical portion of the casing and thus the spacing the movable centering of the power shaft. The mobile centering therefore automatically enters passive position. Conversely, when the turbine is separated from the gear housing, the abutment of the centering device is no longer constrained by the reducer housing, and thus the springs push the centering device to the power shaft, thus forming a support bearing the 'tree.

Advantageously and according to the invention, at least one movable centering - preferably each mobile centering - has a concave contact surface with said power shaft so that it at least partially surrounds said shaft in the active position.

According to another variant, at least one movable centering has a convex contact surface with said power shaft.

Advantageously, a gas turbine engine according to the invention comprises at least two movable centering devices arranged around said power shaft.

The invention also relates to an aircraft, particularly a helicopter, comprising at least one turbine engine according to the invention.

The invention also relates to a turbine engine and an aircraft equipped with a turbine engine, characterized in combination by all or some of the features mentioned above or below.

5. List of Figures

Other objects, features and advantages of the invention will appear on reading the following description given by way of non-limiting and which refers to the appended figures in which:

- Figure 1 is a schematic sectional view of a turbine engine built in a gear housing,

- Figure 2 is a schematic sectional view of a detail of a turbine engine according to an embodiment of the invention on which the centraliser is in passive position,

- Figure 3 is a schematic sectional view of a detail of a turbine engine according to an embodiment of the invention on which the centraliser is in active position,

- Figure 4 is a schematic sectional view of a detail of a turbine engine according to an embodiment of the invention with two mobile centering devices,

- Figure 5 is schematic line view in section of a detail of a turbine engine according to an embodiment of the invention equipped with three mobile centering.

6. Description of an embodiment of the invention In the figure, the scales and proportions are not strictly complied with, for purposes of illustration and clarity. Throughout the following detailed description with reference to the figures, unless otherwise indicated, each element of the turbine engine is described as it is arranged when the turbine engine is in horizontal mounting position on a reduction gearbox. This arrangement is particularly shown in Figure 1. Moreover, the term "axial" refers to locations along the central axis X'X of the turbine engine. The term "radial" refers to locations perpendicular to this central axis. Finally, the elements having the same reference symbols in different figures refer to like elements.

As shown in Figure 1, a gas turbine engine according to the invention comprises a housing 5 in which are mounted a gas generator and a free turbine 6 7. The free turbine 7 is integral with a power shaft 8. According to the embodiment of the figures, the 8 power shaft which carries the free turbine 7 and which connects the turbine engine to a gearbox housing 10, passes inside the gas generator shaft so that end 9 of the power of the power shaft is on the side of the gas generator. The gas generator 6 and its operation are described in detail and are well known in the art. The invention applies of course also to a gas turbine engine whose power shaft does not pass through the gas generator and whose

The power shaft 8 extends in the direction of the turbojet X'X. The power shaft 8 is further configured to be connected to a housing 10 such as a gear box of a helicopter power transmission. The mechanical coupling between the power shaft 8 and the casing 10 reducing not shown in detail in FIGS. The gear housing 10 for example comprises a first stage with a pinion 20 meshed leading adapted to be

by a pinion 8 of the power shaft in the vicinity of its end 9 of power.

A turbine engine according to the invention further comprises a centralizer 12 mobile. The centering device 12 is carried by the casing 5 and can move from a position, called the active position, in which it forms a bearing 8 of the power shaft, and a position, called the passive position, wherein it is spaced from 8 the power shaft.

2 shows the centering device 12 in the passive position and Figure 3 shows the centraliser 12 in the active position.

The centering device 12 is configured and mounted on the housing 5 so that the working position corresponds to a disconnection between the power shaft 8 and the housing 10 and reducing the passive position corresponds to a mechanical coupling between the power shaft 8 and the gear housing.

To do this, the mobile centering device 12 includes a ramp 13 tapered guide axis parallel to the axis X'X of the 8 power shaft. This ramp 13 is shaped to a conical portion 14 of the casing 5 so that a force F parallel to the axis X'X axis exerted on the movable housing in the direction of the housing 5 can cause a displacement of the movable centering device 12 which the spaced radially from the shaft 8 power. This radial movement is obtained by sliding the ramp 13 on the guide portion 14 of the conical casing 5.

This force axis F parallel to the axis X'X is produced by the contact between an element of the casing 10 reducing agent such as for example the stator 21 of the gear 20 driving the gear 10 the housing, and a stop 15 of the movable centering which extends in a plane perpendicular to the axis X'X. This contact between the stator 21 of the pinion gear housing 10 and the stop 15 of the movable centering device 12 results from the recess of the turbine engine in the gear housing. In other words, when mounting the turbine on the gear housing, the contact between the stator 21 and the stop 15 occurs automatically, to generate the force F of axis X'X, and therefore the displacement of the centralizer 12 movable towards the passive position in which it is radially spaced from the shaft 8 power.

The turbine engine also includes according to one embodiment

advantageous shown in Figures 2 and 3, a radial spring 16, mounted between an axial IF portion of the casing 5 and the centering device 12 movable, and an axial spring 17 mounted between a radial portion 52 of the casing 5 and the centralizer 12 mobile. According to the embodiment of the figures, the radial portion 52 of the casing 5 is an extension of the conical portion 14 of the housing 5. Each spring has one end fixed relative to the housing and another end slidably relative to the movable centering.

These springs therefore possible to form a resultant force which opposes the spontaneous sliding of the mobile 12 centering on the conical portion 13 of the housing 5, towards the conical portion 13 of the casing 5.

In Figure 2, the springs 16, 17 are compressed by the action of the force

F. The movable centering 12 is moved into its passive position in which it is radially spaced from the shaft 8 of power and is not in mechanical interaction with the 8 power shaft. In this position, the landing of the end 9 of power of the power shaft 8 is directly formed by the gear housing 10. In particular, the centering of the power shaft 8 is directly carried out by the contact between the pinion 20 leading from the gear housing 10 and the end 9 of the power shaft. The contact between the pinion 20 and the power shaft 8 is shown schematically by reference 22 in Figure 2.

In Figure 3, the turbine engine is separated from the gear housing 10. In this situation, the force F has disappeared, so that the springs 16, 17 were able to relax to repel the mobile centralizer 12 of the housing 5. The movable centering device 12 is in its active position in which it is in contact with 8 the power shaft. This contacting occurs at a surface 18 of the movable contact 12 and a centralizer 11 of centering scope of the 8 power shaft. When the surface 18 of contact 12 movable centering device is in contact with the bearing surface 11 for centering the power shaft 8, the mobile centering device 12 forms a shaft support bearing 8 power. In Figure 3, the mobile centering device 12 is supported forced against the bearing surface 11 for centering, which allows to form a bearing of the 8 power shaft. The 8 power shaft is self-maintained. This is the operative position of the centering device 12 mobile.

According to an advantageous embodiment, the surface 18 of contact 12 movable centering is concave so that the centering device surrounds at least partially said power shaft 8 in the active position. This improves the maintenance of the power shaft 8 by the centering device 12 movable in the active position.

According to an advantageous embodiment shown in Figure 4, the turbine engine comprises two centering devices 42, 43 movable arranged around the 8 power shaft, diametrically opposed relative to each other. Each centraliser 42, 43 is movable for example a centralizer as described in connection with Figures 2 and 3.

According to another embodiment shown in Figure 5, the turbine engine comprises three centering devices 44, 45, mobile 46 uniformly distributed around the shaft 8 of the free power turbine of the engine. According to the embodiment of Figure 5, each centering device is identical to that described in connection with Figures 2 and 3, with the exception of the surface 18 contact each centralizer that is not concave, but convex in this embodiment.

According to other embodiments not shown in the figures, the turbine engine may include both concave and convex centering centering.

According to other embodiments not shown in the figures, the turbine engine may include more than three mobile centering distributed around the power shaft.

The invention also relates to a helicopter comprising at least one turbine engine according to the invention.

Also note that a mobile centering of a turbine engine according to the invention can usefully be fitted to a power shaft of an internal combustion engine (piston or rotor).

It can also be used for connection of a gas turbine of an aircraft propeller turboprop reducer (fixed wings).

CLAIMS

1. A gas turbine engine comprising a housing (5) in which is arranged a generator (6) and a gas turbine (7) freely mounted on a shaft (8) power configured to be coupled / uncoupled mechanically to a housing (10) reducer,

characterized in that said turbine engine comprises at least one centering device (12) movable between a position, called the active position, in which it forms a bearing of said shaft (8) of power and corresponding to a mechanical uncoupling between said shaft (8) power and said housing (10) reducer, and a position, called the passive position, wherein it is spaced from said shaft (8) of power and corresponding to a mechanical coupling between said shaft (8) of power and said housing (10) gearbox.

2. A turbine engine according to claim 1, characterized in that at least one centering device (12) mobile is configured to automatically switch from said active position to said inactive position upon mating of said shaft (8) of said power box ( 10) reducing agent and to be able to automatically switch between said passive position to said active position during uncoupling of said shaft (8) of power to said housing (10) gearbox.

3. A turbine engine according to claim 2, characterized in that at least one centering device (12) comprises a movable ramp (13) of conical with an axis parallel to the axis of guiding (X'X) of said power shaft, and shaped a portion (14) tapered from said housing (5) so that the sliding of said ramp (13) for guiding on said portion (14) tapered from said housing (5) moves said centraliser (12) movable relative to said shaft (8 ) power.

4. A turbine engine according to claim 3, characterized in that it comprises at least one spring (16) radially mounted perpendicularly to said shaft (8) power between said housing (5) and a centraliser (12) movable, and at least a spring (17) axially extending between said housing (5) and the centralizer (12) movable, said springs (16, 17) being fixedly mounted relative to the housing and slidable relative to the movable centering device, and configured to be able to exert a resultant force which opposes the spontaneous sliding of said ramp (13) on said guiding portion (14) of said conical housing (5) toward said housing (5).

5. A gas turbine engine according to claim 4, characterized in that at least one centering device (12) has a movable abutment (15) extending in a plane perpendicular to the axis (X'X) of said shaft (8) power facing a bearing surface of the housing (10) gear so that the mechanical coupling between said shaft (8) of power and said housing (10) reducing generates a mechanical contact between said bearing surface and said abutment (15) which drives, by compression of said springs (16, 18), the sliding of said centraliser (12) on said portion (14) of said conical casing (5) of said active position in which it forms a shaft bearing ( 8) power to said passive position in which it is spaced from the shaft (8) power.

6. A gas turbine engine according to one of claims 1 to 5, characterized in that at least one centering device (12) has a movable surface (18) of concave contact with said shaft (8) power so that it surrounds at least partially said shaft (8) of power in the active position.

7. A gas turbine engine according to one of claims 1 to 6, characterized in that it comprises at least two centering devices (42, 43; 44, 45, 46) movably arranged around said shaft (8) power.

8. Helicopter comprising at least one turbine engine according to one of claims 1 to 7.