AIRCRAFT TURBOMACHINE ASSEMBLY INCLUDING AN AUTOMATIC LUBRICANT DISTRIBUTION SHUT-OFF DEVICE DURING MECHANICAL DISSOLUTION BETWEEN TWO PARTS

Abstract

The invention relates to an assembly for an aircraft turbomachine comprising: - a fixed structure (20) of the turbomachine; - a rotating shaft (34) of the turbomachine; - a bearing (42a) for guiding the rotation of the rotating shaft; - a bearing support (46); - a mechanical decoupling device (48), forming a mechanical link between the bearing support (46) and the fixed structure (20), under normal operating conditions of the turbomachine; - a lubrication chamber (54); - a lubricant supply system (56) comprising an automatic lubricant distribution shut-off device (70), configured to automatically switch from an inactive lubricant distribution state to an active distribution shut-off state. Figure 2.

Description

Title of the invention: AIRCRAFT TURBOMACHINE ASSEMBLY COMPRISING AN AUTOMATIC LUBRICANT DISTRIBUTION SHUT-OFF DEVICE, WHEN MECHANICAL DECOUPLING BETWEEN TWO PARTS technical field

[0001] The invention relates to the field of aircraft turbomachinery, comprising a mechanical decoupling device between two parts of the turbomachine.

[0002] Preferably, the invention relates to the field of aircraft turbomachinery with fan(s), and, more particularly, to the means implemented within these turbomachinery to counteract the imbalance caused by a fan blade failure (from the English "Fan Blade Out"). This issue is addressed in several documents, including documents FR 2 752 024 A1, FR 2 888 621 A1, and document FR 2 966 208 A1.

[0003] The invention applies in particular to turbojets, and even more particularly to turbofan engines. STATE OF PRIOR ART

[0004] In the prior art, it is known that turbomachines exist in which a rotating shaft, for example a fan shaft, is guided in rotation by bearings. These bearings are carried by bearing supports, the latter being attached to a fixed structure of the turbomachine, for example a turbomachine casing, such as the intermediate casing in the case of a turbofan engine.

[0005] To cope with an incident causing an extreme dynamic situation, such as the loss of a fan blade, it is known to implement a mechanical decoupling device to ensure the fusible mounting of one of the bearing supports on the fixed structure of the turbomachine. Such a decoupling device thus ensures a mechanical connection between the bearing support and the fixed structure under normal operating conditions of the turbomachine. Furthermore, this fusible mechanical decoupling device is configured so that this mechanical connection is broken under the effect of a decoupling moment of predetermined magnitude occurring under accidental conditions such as those described above. The decoupling moment, originating from the rotating shaft which has undergone a significant imbalance, generates a rupture of the mechanical connection, followed by an accidental displacement of the bearing support relative to the fixed structure of the turbomachine.

[0006] The breaking of the mechanical link, as well as this accidental displacement of the bearing support, ensures that excessively high forces are not introduced into the fixed structure of the turbomachine, at the risk of causing much more severe damage to it.

[0007] In other words, under normal operating conditions of the turbojet engine, the fusible mechanical linkage is sufficiently strong to withstand the radial forces transmitted by the bearing, which serves to maintain the rotation of the shaft about its longitudinal axis. In an exceptional case, such as the loss of one or more blades driven by the shaft, the shaft experiences a significant imbalance, which causes extremely high radial forces in the turbojet engine structures, and in particular in the bearing supports and the housing to which these supports are attached. As mentioned previously, the fusible mechanical linkage is designed to break under the effect of a decoupling moment of predetermined magnitude, or greater than that, which then leads to the accidental displacement of the bearing support in its decoupled state.

[0008] While this accidental movement of the bearing support is indeed desirable to limit the transmission of extreme forces within the turbomachine, it can, however, present a drawback when this bearing support partially delimits a lubrication chamber. In this situation, the accidental movement of the support can cause a breach of the chamber's seal, and therefore unwanted lubricant leaks towards other parts of the turbomachine.

[0009] Consequently, there is a need to prevent or limit these potential lubricant leaks from the housing after the fusible mechanical link between the bearing support and the fixed structure of the turbomachine has been broken. Description of the invention

[0010] To at least partially meet this need, the invention first relates to an assembly for an aircraft turbomachine comprising:

[0011] - a fixed structure of the turbomachine;

[0012] - a rotating shaft of the turbomachine;

[0013] - a bearing for guiding the rotation of the rotating shaft;

[0014] - a bearing support, comprising a first end supporting the shaft guide bearing, and a second end opposite the first end;

[0015] - a mechanical decoupling device, forming a mechanical link between the second end of the bearing support and the fixed structure, under normal operating conditions of the turbomachine, the mechanical decoupling device being configured so that said mechanical link is broken under the effect of a decoupling moment of intensity greater than or equal to a predetermined intensity occurring under accidental conditions, said decoupling moment originating from the rotating shaft and generating, after breakage of the mechanical link, an accidental displacement of the bearing support relative to the fixed structure of the turbomachine;

[0016] - a lubrication chamber in which the bearing is located, the chamber being partially delimited by the bearing support;

[0017] - a lubricant supply system, configured to distribute lubricant into the lubrication chamber.

[0018] According to the invention, the supply system includes an automatic lubricant distribution stop device, configured to automatically switch from an inactive lubricant distribution state to an active distribution stop state, upon said accidental displacement of the bearing support.

[0019] The invention thus makes it possible to take advantage of the accidental displacement of the bearing support to automatically stop the lubrication in the chamber. Therefore, even if this accidental displacement of the bearing support breaks the seal of the chamber, the amount of lubricant escaping from this chamber remains advantageously limited by the automatic shutdown of the lubricant distribution within this chamber.

[0020] The invention also has at least one of the following optional features, taken individually or in combination.

[0021] Preferably, the automatic lubricant distribution shut-off device is a passive device. Alternatively, it could be an active device, for example, capable of transmitting a closing signal to a solenoid valve of the lubricant supply system, after detecting accidental displacement of the bearing support.

[0022] In the preferred solution involving a passive design, i.e. without additional energy input, several realizations are possible.

[0023] Preferably, the automatic lubricant distribution shut-off device comprises a shut-off valve, as well as a retaining member attached to the bearing support, and configured to keep the valve in the open position under normal operating conditions, in order to keep the automatic lubricant distribution shut-off device in its inactive lubricant distribution state, the automatic distribution shut-off device also being configured so that the valve automatically moves into a shut-off position bringing the distribution shut-off device into its active distribution shut-off state, when the retaining member follows said accidental movement of the bearing support.

[0024] Preferably, the retaining member is a support on a movable shut-off element of the valve, and the movable shut-off element is subjected to a force forcing it towards its shut-off position, this force preferably resulting from lubricant pressure and / or an elastic return means. Alternatively, the retaining member could simply comprise a fusible part, designed to break under the aforementioned accidental conditions, in the same way as the fusible mechanical connection between the bearing support and the fixed structure of the turbomachine. In such a case, once the fusible retaining member is separated from the valve, its movable element can automatically reach its shut-off position under the effect of the aforementioned force. In both cases, the chosen design advantageously allows for a self-sealing principle of the valve.

[0025] Preferably, the supply system comprises a first line, as well as at least one second line connected to the first line via a fitting and supplied with lubricant by the first line. The automatic lubricant distribution shut-off device is configured to allow / prevent the flow of lubricant through the first line or through the second line. For greater efficiency, the automatic shut-off device preferably acts on the first line. If, on the other hand, it is intended to act on one or more of the second lines, or even on each of them, then such an automatic shut-off device is associated with each of the relevant second lines. Another possibility is to combine these two solutions to further guarantee the desired reliability of the automatic shut-off.

[0026] Preferably, the second pipe is integral with the bearing support, the shut-off valve is provided on the end so as to allow / prevent the circulation of lubricant through the second pipe, and the support member, cooperating with the movable shut-off element of the valve under normal operating conditions, is provided on the second pipe.

[0027] Preferably, the first pipe is a main lubricant supply pipe, and the second pipe is an internal distribution pipe to the lubrication chamber.

[0028] Preferably, the movable closing element of the valve is a ball or a butterfly.

[0029] Preferably, the rotating shaft is a blower shaft of the turbomachine. Alternatively, it could be any shaft of the turbomachine, driving blades rotating about the axis of that shaft.

[0030] Preferably, the fixed structure is an intermediate housing of the turbomachine.

[0031] The invention also relates to an aircraft turbomachine comprising at least one such assembly, this turbomachine preferably being a dual-flow turbomachine.

[0032] Other advantages and features of the invention will appear in the detailed, non-limiting description below. Brief description of the drawings

[0033] This description will be made with reference to the attached drawings, among which;

[0034] [Fig-1] represents a longitudinal cross-sectional view of a turbojet engine according to the invention;

[0035] [Fig.2] shows a longitudinal half-sectional view of part of the turbojet engine shown in [Fig.1], according to a first preferred embodiment of the invention;

[0036] [Fig.3] represents a cross-sectional view of part of the feeding system lubricant shown in [Fig.2], in a state such as occupied under normal operating conditions of the turbomachine;

[0037] [Fig.4] represents a view similar to that of [Fig.2], after breaking the bond mechanical connection between the bearing support and the fixed structure of the turbojet engine;

[0038] [Fig.5] represents a view similar to that of [Fig.3], in a state such that occupied after an incident which caused the mechanical link to break, as well as an accidental displacement of the bearing support;

[0039] [Fig.6] represents a view similar to that of [Fig.2], according to a second mode of preferred embodiment of the invention; and

[0040] [Fig.7] represents a view similar to that of [Fig.6], after breaking the bond mechanical connection between the bearing support and the fixed structure of the turbojet engine. DETAILED EXPLANATION OF PREFERRED METHODS OF IMPLEMENTATION

[0041] With reference first to [Fig. 1], an aircraft turbomachine 1, according to the invention, is shown. This is a twin-spool, turbofan engine. However, it could be a turbomachine of another type, for example a turboprop, without departing from the scope of the invention.

[0042] The turbomachine 1 has a longitudinal axis 3 around which its various components extend. It comprises, from upstream to downstream along a main direction of gas flow through this turbomachine, a blower 2, a low-pressure compressor 4, a high-pressure compressor 6, a combustion chamber 8, a high-pressure turbine 10 and a low-pressure turbine 12.

[0043] Conventionally, these elements define a primary channel 14a through which a primary flow 16a circulates, and a secondary channel 14b through which a secondary flow 16b circulates. In this dual-flow design, an intermediate casing 20 is provided, arranged downstream of the blower 2. The intermediate casing comprises a hub 22, radial arms 24, and an external ferrule 26 extending downstream a blower housing.

[0044] Here, the high-pressure turbine 10 and the high-pressure compressor 6 are connected by a high-pressure shaft 30, while the low-pressure turbine 12 and the low-pressure compressor 4 are connected by a low-pressure shaft 32, preferably passing through the high-pressure shaft 30. A rotating blower shaft 34 is also provided, driving the blower blades in rotation around the axis 3, on which the three shafts 30, 32, 34 are centered.

[0045] In the configuration shown, the blower shaft 34 is driven by means of a reducer 36, which is itself driven by the low-pressure shaft 32. A direct drive solution, without a reducer, is also possible.

[0046] With more specific reference to [Fig.2], a turbojet assembly 40 is shown, which is in the form of a first preferred embodiment of the invention, and which is shown in a configuration as adopted under normal operating conditions of the turbojet.

[0047] This assembly 40 first of all comprises a fixed structure, i.e. a part of the stator, which here includes at least a part of the intermediate housing 20, and preferably its radially internal part integrating the hub.

[0048] The assembly 40 also includes the rotating blower shaft 34, as well as an upstream guide bearing 42a and a downstream guide bearing 42b. These two bearings ensure, in particular, the rotational guidance of the shaft 34, and they can also contribute to the axial locking of this shaft. The downstream bearing 42b is supported by a bearing support 44, fixed to the intermediate housing 20 in a conventional manner.

[0049] Furthermore, the upstream bearing 42a is supported by a bearing support 46, fixed to the intermediate housing 20 via a mechanical decoupling device 48. Indeed, the bearing support 46 comprises a first end supporting the upstream bearing 42b, and a second end opposite the first end, attached to a fastening member 50 belonging to the intermediate housing 20. This fastening is achieved using the mechanical decoupling device 48, which forms a mechanical link between the second end of the bearing support 46 and the fastening member 50. This mechanical link, which is fusible as will be described below, is maintained under normal operating conditions of the turbojet engine.

[0050] The mechanical decoupling device 48 can take any form known in the prior art, such as an annular row of fusible bolts or screws, each passing through the second end of the bearing support 46 and the fastening member 50 of the intermediate housing 20. This device 48 is configured so that the fusible mechanical connection is broken under the effect of a decoupling moment. of intensity greater than or equal to a predetermined intensity, occurring under accidental conditions, for example following the loss of one or more blower blades 2a.

[0051] The assembly 40 also includes a lubrication chamber 54, in which the bearings 42a, 42b are located. This lubrication chamber 54 is partially delimited by the bearing support 46, as well as by the mechanical decoupling device 48 as long as the mechanical link it forms remains intact, that is to say as long as it is not broken under the effect of excessive loads.

[0052] Finally, the assembly 40 includes a lubricant supply system 56, configured to distribute lubricant into the lubrication chamber 54. Here, the system 56 comprises a first lubricant circulation line 58, preferably corresponding to a main lubricant supply line, located wholly or partly outside the lubrication chamber 54. The system 56 also comprises one or more secondary lubricant circulation lines 60, corresponding to internal distribution lines within the lubrication chamber 54, in that each is arranged wholly or partly inside this chamber. Here, a single secondary line 60 is shown, but it should be understood that each of the secondary lines 60 is connected to the first line 58 and is intended to distribute lubricant to different locations within the chamber 54.For this reason, the first pipe is called the main pipe, while the second pipes, arranged downstream and supplied with lubricant by the first pipe, are called lubricant redistribution pipes.

[0053] For at least one of these second pipes 60, the pipe end is engaged in a fitting 65, connecting the first pipe 58 to the second pipe 60, thus defining a bifurcation in the main flow path of the lubricant in the first pipe 58. This is preferably a leak-proof connection, for example using a seal 64 as shown in [Fig. 3], but allowing for easy disengagement, for the purposes described below. To achieve this, a sliding fit is possible, for example, between these two joined parts. The second pipe 60 is held in position by being fixed to the bearing support 46, either directly or indirectly, using suitable fastening means 68. In this way, the second pipe 60 and the bearing support 46 are fixed to each other.

[0054] At the end 65 of the first pipe 58, the pipe is equipped with an automatic lubricant distribution shut-off device 70. This device 70 includes a shut-off valve 72 provided on the end 65, so as to allow / prevent the flow of lubricant from this first pipe 58 through the second pipe 60. This is preferably a passive, self-sealing ball valve 74. The automatic distribution shut-off device 70 The lubricant, which is therefore passive in nature, also includes a retaining element 76 attached to the bearing support 46, in that it is fixedly supported by the fitted end of the second pipe 60. This is a push-button shaped support element 76, configured to hold the valve 72 in the open position under normal operating conditions, in order to keep the automatic lubricant distribution shut-off device 70 in an inactive lubricant distribution state. This state allows the lubricant from the first pipe 58 to flow through the second pipe 60, thanks to the push-button bearing on the ball 74, which forms the movable closing element of the valve 72.The pusher 76 thus counteracts another force Fl forcing the ball 74 towards its closing position, this force resulting preferably from the lubricant pressure within the nozzle 65 whose lubricant passage channel communicates with the lubricant flow path through the first channel 58.

[0055] In other words, under normal operating conditions of the turbojet engine, the pusher 76 pushes the ball 74 back, overcoming the force Fl applied by the lubricant to the ball, which allows the valve 72 to occupy its open position, placing the automatic lubricant distribution shut-off device 70 in its inactive lubricant distribution state. In this state, lubricant is introduced into the chamber 54 through the opposite end of the second pipe 60.

[0056] One of the features of the invention lies in the evolution of the state of the valve 72 in the event of an incident or exceptional problem leading to the loss of one or more blower blades 2a. In this accidental scenario, the fusible mechanical connection provided by the mechanical decoupling device 48 is designed to break due to the observed imbalance. Following this mechanical decoupling, which occurs under the effect of a decoupling moment of a magnitude greater than or equal to a predetermined magnitude, this decoupling moment originating from the blower shaft 34 also generates an accidental displacement of the bearing support 46 relative to the intermediate housing 20 to which it is no longer connected. This situation, occurring as a result of extreme dynamic loading, is shown in Figures 4 and 5.

[0057] Since the second pipe 60 follows the accidental movement of the bearing support 46, here generally upstream, its movement causes a disengagement of the end of the second pipe 60 from the end fitting 65, and therefore a separation between the two pipes 58, 60. This state is best represented on [Fig.5].

[0058] This allows the automatic lubricant distribution shut-off device 70 to automatically switch from its inactive lubricant distribution state to an active lubricant distribution shut-off state, simply due to the accidental movement of the bearing support 46. Indeed, the automatic distribution shut-off device 70 is configured so that the valve 72 automatically moves into a closed position, bringing the shut-off device 70 into its active distribution stop state, when the plunger follows the accidental movement of the bearing support 46. This is because, during such a movement of the plunger 76, indicating an accidental situation, the ball 74 of the valve 72 is subjected only to the force Fl applied by the lubricant in the nozzle 65. This ball 74 then closes the lubricant passage within the valve, which consequently automatically adopts its closed position, preventing the distribution of lubricant into the second channel 60, and therefore into the chamber 54. While in this state, the circulation of lubricant through the second channel 60 is prevented, the lubricant stopped in the nozzle 65 can nevertheless continue to flow downstream in the first channel 58, along its main path.

[0059] Advantageously, this passive, simple and reliable solution makes it possible to limit the amount of lubricant which escapes from chamber 54 after accidental displacement of the bearing support 46, through the passage 78 defined between the second end of this support, and the fixing member 50 of the intermediate housing 20.

[0060] Figures 6 and 7 illustrate a second preferred embodiment of the invention, which has many similarities with the first embodiment. Here, the second pipelines are not shown, but they are located downstream so that they can be supplied with lubricant by the main pipeline 58. The automatic lubricant distribution shut-off device 70 is fully integrated into the first pipeline 58 of the lubricant supply system 56. The valve 72 includes a butterfly-shaped movable shut-off element 74, rotatably mounted in the lubricant passage defined by the first pipeline 58.

[0061] Under normal operating conditions as shown in [Fig. 6], the automatic lubricant distribution shut-off device 70 assumes its inactive lubricant distribution state, with its valve 72 in the open position. This position is maintained by a pusher 76, which is directly connected to the bearing support 46, and which therefore follows the movement of the latter in the event of an incident causing mechanical decoupling of the support 46, relative to the intermediate housing 20.

[0062] The pusher 76 thus counteracts another force Fl forcing the butterfly 74 towards its position of closing the lubricant passage, this force Fl here preferably resulting from an elastic return means, such as for example a compression spring 80 arranged between an end of the butterfly, and a fixed part of the assembly 40.

[0063] In other words, under normal operating conditions of the turbojet engine, the pusher 76 pushes the butterfly valve 74 into a position allowing the lubricant to circulate through the first channel 58, overcoming the force Fl applied by the spring 80. This allows the valve 72 to occupy its open position, placing The automatic lubricant distribution shut-off device 70 in its inactive lubricant distribution state. In this state, lubricant is introduced into chamber 54, via the second pipe(s), which are themselves supplied by the first pipe 58.

[0064] In the event of an incident or exceptional problem leading to the loss of one or more fan blades 2a, the fusible mechanical connection provided by the mechanical decoupling device 48 is broken, and the decoupling moment also generates an accidental displacement of the bearing support 46, relative to the intermediate housing 20 to which it is no longer connected. This situation, occurring following an extreme dynamic load, is shown in [Fig. 7].

[0065] Since the pusher 76 follows the accidental movement of the bearing support 46, here generally upstream, its movement causes this pusher to disengage relative to the butterfly 74 of the valve 72, this butterfly then being subjected only to the force Fl of the spring 80. This therefore allows the automatic lubricant distribution shut-off device 70 to automatically switch from its inactive state of lubricant distribution to its active state of lubricant distribution shut-off, simply due to the accidental movement of the bearing support 46. This is achieved thanks to the butterfly 74, which closes the lubricant passage under the effect of the spring 80, and which therefore allows the valve to automatically adopt its closed position, preventing the circulation of lubricant through the first channel 58, and thus prohibiting the distribution of lubricant in the second channels and in the chamber 54.

[0066] Of course, various modifications can be made by a person skilled in the art to the invention just described, solely by way of non-limiting examples. In particular, the elements of the different preferred embodiments are combinable and interchangeable, and in this regard, it is noted that in the figures, the elements bearing the same numerical references correspond to identical or similar elements. It is noted that either one or the other of the first and second preferred embodiments described above can be implemented, or both simultaneously. More generally, the automatic lubricant distribution shut-off device(s) is positioned to act on the circulation of lubricant either through the second line, or through the first line, or through both.In the case where it concerns only one of the two, it is preferentially the first pipe, namely the main pipe arranged furthest upstream in the lubricant supply system.

Claims

Demands

1. Assembly (40) for aircraft turbomachine comprising: - a fixed structure (20) of the turbomachine; - a rotating shaft (34) of the turbomachine; - a bearing (42a) for rotating the rotating shaft; - a bearing support (46), comprising a first end supporting the shaft guide bearing (42a), and a second end opposite the first end;- a mechanical decoupling device (48), forming a mechanical link between the second end of the bearing support (46) and the fixed structure (20), under normal operating conditions of the turbomachine, the mechanical decoupling device (48) being configured so that said mechanical link is broken under the effect of a decoupling moment of magnitude greater than or equal to a predetermined magnitude occurring under accidental conditions, said decoupling moment originating from the rotating shaft (34) and generating, after breakage of the mechanical link, an accidental displacement of the bearing support (46) relative to the fixed structure (20) of the turbomachine; - a lubrication chamber (54) in which the bearing (42a) is located, the chamber being partially delimited by the bearing support (46);- a lubricant supply system (56), configured to distribute lubricant into the lubrication chamber (54), characterized in that the supply system (56) includes an automatic lubricant distribution stop device (70), configured to automatically switch from an inactive lubricant distribution state to an active distribution stop state upon said accidental displacement of the bearing support (46).

2. Assembly according to claim 1, characterized in that the automatic lubricant distribution shut-off device (70) is a passive device.

3. Assembly according to claim 2, characterized in that the automatic lubricant distribution shut-off device (70) comprises a shut-off valve (72), as well as a retaining member (76) integral with the bearing support (46), and configured to maintain the valve (72) in the open position under normal conditions of operation, in order to keep the automatic lubricant distribution stop device (70) in its inactive lubricant distribution state, the automatic distribution stop device (70) also being configured so that the valve (72) automatically moves into a closed position bringing the distribution stop device (70) into its active distribution stop state, when the retaining member (76) follows said accidental displacement of the bearing support (46).

4. Assembly according to claim 3, characterized in that the retaining member (76) is a support member on a movable sealing element (74) of the valve (72), and in that the movable sealing element (74) is subjected to a force (Fl) forcing it in the direction of its sealing position, this force preferably resulting from a lubricant pressure, and / or an elastic return means (80).

5. Assembly according to claim 3 or 4, characterized in that the supply system (56) comprises a first pipe (58), as well as at least one second pipe (60) connected to the first pipe via a fitting (65), and supplied with lubricant by this first pipe (58), and in that the automatic lubricant distribution shut-off device is configured to allow / prevent the flow of lubricant through the first pipe (58), or through the second pipe (60).

6. 6. Assembly according to claim 5, characterized in that the second pipe (60) is integral with the bearing support (46), in that the shut-off valve (72) is provided on the end (65) so as to permit / prevent the circulation of lubricant through the second pipe (60), and in that the support member (76), cooperating with the movable shut-off element (76) of the valve (72) under normal operating conditions, is provided on the second pipe (60).

7. 7. Assembly according to claim 5 or 6, characterized in that the first pipe (58) is a main lubricant supply pipe, and in that the second pipe (60) is an internal distribution pipe to the lubrication chamber (54).

8. 8. Assembly according to any one of claims 4 to 7, characterized in that the movable sealing element (74) of the valve (72) is a ball or a butterfly.

9. 9. Assembly according to any one of the preceding claims, characterized in that the rotating shaft (34) is a blower shaft of the turbomachine.

10. Assembly according to any one of the preceding claims, characterized in that the fixed structure (20) is an intermediate housing of the turbomachine.

11. 11. Aircraft turbomachine (1) comprising at least one assembly (40) according to any one of the preceding claims, the turbomachine preferably being a twin-flow turbomachine.

Images