Cowling for an aircraft turbomachine compressor rotor

Abstract

The invention relates to a cover (40) for a compressor disc (24) for an aircraft turbomachine (1), the cover comprising: - a body (42), intended to be fixed to a compressor disc (24) by means of fixing screws (34), the body (42) having a generally symmetrical shape of revolution about a central axis (Y) and having an annular cavity for containing all the screw heads of the fixing screws (34); - a movable cover (44) closing the annular cavity of the body (42) and having at least one screw hole for the passage of a screwing tool, the movable cover (44) being rotatable about the central axis (Y) relative to the body (42), so as to allow modification of the angular position of the screw hole(s) relative to the body (42). Figure 4.

Description

Title of the invention: Hood for an aircraft turbomachine compressor rotor. Technical field

[0001] The present invention relates to the field of aeronautics. It relates more particularly to a cover for a compressor disc of an aircraft turbomachine, as well as to an assembly of a compressor disc and such a cover. State of the art

[0002] Turbomachinery used for aircraft propulsion includes a gas generator. The gas generator includes, in particular, from upstream to downstream with respect to the direction of gas flow, a rectifier, a low-pressure compressor, and a high-pressure compressor.

[0003] Certain components of an aircraft turbomachine operate in a hostile environment and are exposed to high temperatures. This is the case, for example, with high-pressure compressor rotors, which are rotating elements. These high temperatures induce thermal stresses that can affect the service life of these components.

[0004] To prevent excessive heating, it is known to ensure ventilation of the compressor discs by circulating an airflow near these elements. However, certain protruding elements present on the discs, such as screw heads, are likely to generate viscous heating of the ventilation air when it encounters these elements. To remedy this problem, it is known to provide a cover to protect all the screws securing a compressor disc. Such a cover is shown in [Fig. 1], which shows a perspective cross-sectional view of a cover C attached to a compressor disc D. The cover C is in the form of a hollow, annular piece, having a first wall PI and a second wall P2, each wall having a series of opposite holes T1, T2. As shown in [Fig.[l] The holes T1 in the first wall P1 allow the cover C to be attached to a compressor disc D via the disc's mounting screws V, while the holes T2 in the second wall P2 provide access to the heads of the mounting screws V and allow the passage of a screwing tool. By covering the protrusions formed by the screw heads of the disc D, the cover in [Fig. 1] drastically reduces the viscous heating mentioned above. However, its effectiveness can be further improved. Indeed, the holes T2 in the second wall P2, although not protrusions, . They still generate viscous heating when they encounter ventilation air.

[0005] The objective of the present invention is to provide a cover for a rotating turbomachine disc which makes it possible to overcome the disadvantages of the prior art, and in particular those set out above. Description of the invention

[0006] To this end, the invention relates to a compressor disc cover for an aircraft turbomachine, the cover comprising: - a body, intended to be fixed to a compressor disc by means of fixing screws, the body having a general symmetrical shape of revolution around a central axis and comprising an annular cavity intended to contain all the screw heads of the fixing screws; - a movable cover closing the annular cavity of the body and having at least one screw hole for the passage of a screw tool, the movable cover being movable in rotation around the central axis relative to the body, so as to allow modification of the angular position of the screw hole(s) relative to the body.

[0007] Thus, by providing a hood with a rotating movable cover, the movable cover having at least one screw hole, it is possible to modify the angular position of the movable cover and therefore of the screw hole(s), in order to successively position the screw hole (or one of the screw holes) opposite each fixing screw location and to allow normal access to each fixing screw. The movable cover thus presents a smooth surface except for one or more very limited holes. The hood according to the invention therefore has a predominantly smooth external surface, thereby drastically limiting the viscous heating observed on known hoods.

[0008] The hood according to the invention may include one or more of the following optional features, considered alone or according to all possible combinations.

[0009] According to one feature, the body has a bottom wall of annular shape, extending radially around the central axis, the bottom wall being connected to a first circumferential wall, or internal circumferential wall, and to a second circumferential wall, or external circumferential wall, the bottom wall delimiting with the internal and external circumferential walls the annular cavity of the body.

[0010] According to one feature, the movable cover has a general annular shape with its axis coinciding with the central axis and is at least partially inserted between the inner circumferential wall and the outer circumferential wall.

[0011] According to one feature, the inner circumferential wall comprises an element of internal guidance and the external circumferential wall includes an external guide element, the guide elements ensuring guidance of the movable cover in rotation around the central axis while preventing translational movement of the movable cover in a direction parallel to the central axis.

[0012] According to one feature, the internal guide element is a rib forming a projection from a radially external surface of the internal circumferential wall and extending circumferentially around the central axis, and the external guide element is a rib forming a projection from a radially internal surface of the external circumferential wall and extending circumferentially around the central axis, the movable cover having an internal circumferential groove and an external circumferential groove cooperating respectively with the internal and external guide elements.

[0013] According to one feature, the body is formed by two body parts symmetrical with respect to a plane including the central axis, and the movable cover is formed by two cover parts symmetrical with respect to a plane including the central axis.

[0014] According to one feature, the hood has a number of screw holes less than or equal to 4, and for example equal to 1.

[0015] The invention also relates to an assembly of a turbomachine compressor disc and a hood as defined above, the hood being fixed to the disc by means of a plurality of fixing screws, the screw hole or at least one of the screw holes cooperating with a rotational locking element of the movable cover.

[0016] According to a feature of this assembly, the rotation blocking element or elements of the movable cover is a screw head of a fixing screw penetrating at least partially into the corresponding screw hole, or an element attached to a fixing screw head penetrating at least partially into the corresponding screw hole.

[0017] The invention also relates to an aircraft turbomachine, comprising at least one hood as defined above, or an assembly of a compressor disc and a hood conforming to that defined above.

[0018] The invention also relates to an aircraft comprising at least one propulsion assembly comprising a turbomachine as defined above. Brief description of the drawings

[0019] [Fig-1] The [Fig. 1], already described, is a partial perspective view of a known compressor disc cover.

[0020] [Fig.2] Fig.2 is a schematic cross-sectional view of a turbomachine comprising a high-pressure compressor, at least one disc of which is equipped with a cover conforming to the invention.

[0021] [Fig.3] The [Fig.3] is a detail view of the high-pressure compressor of the turbomachine of the [Fig.2], showing a compressor disc equipped with a hood according to the invention.

[0022] [Fig.4] The [Fig.4] is a partial schematic perspective view cut off from a compressor disc equipped with a cover according to the invention.

[0023] [Fig.5] The [Fig.5] is a view analogous to the [Fig.4], showing the body of the hood and the fixing screws.

[0024] [Fig.6] The [Fig.6] is a view of the whole of the [Fig.4] seen in section.

[0025] [Fig.7] The [Fig.7] is a detail view of the [Fig.5].

[0026] [Fig.8] The [Fig.8] is a half view of the whole of the [Fig.4] seen from the front.

[0027] [Fig.9] Fig.9 is a detail view similar to that of Fig.7, showing a first example of rotational blockage of the movable ring.

[0028] [Fig. 10] The [Fig. 10] is a view analogous to that of the [Fig.7], showing a second example of blocking the rotation of the movable ring.

[0029] [Fig. 11] The [Fig. 11] is a partial schematic perspective cutaway view of a compressor disc equipped with a hood according to the invention, the body of the hood being formed of two parts.

[0030] Fig. 12 is a front view of the compressor disc and the cover of Fig. 11. Detailed description

[0031] Figure 2 represents an aircraft turbomachine 1 according to the invention, in this example a turbofan engine (shown without the normally associated nacelle). The turbomachine 1 has an air inlet 2 through which a gas flow enters the turbomachine. The gas flow is accelerated by a fan 3. Downstream of the fan 3, the gas flow is split into a primary flow entering an internal annular channel 4, or primary channel 4, and a secondary flow entering an external annular channel 5 surrounding the internal annular channel 4, or secondary channel 5. In the primary channel 4, the primary flow successively passes through an inlet straightener 6 and a gas generator.In the example, the gas generator comprises, from upstream to downstream (with respect to the direction of gas flow), a low-pressure compressor 7, a high-pressure compressor 8, a combustion chamber 9, a high-pressure turbine 10 and a low-pressure turbine 11, and a gas exhaust casing 12 to which an exhaust nozzle (not shown) is connected. The secondary stream 5 is defined in part by a blower casing. 13 surrounding the blower 3 and by a nacelle surrounding the turbomachine (not shown).

[0032] Each compressor 7, 8 comprises several stages, each stage comprising a row of moving blades and a row of fixed blades. The fixed blades are attached to compressor housings, the moving blades being attached to rotating discs. The fixed blades and housings together form the stator 20 of the compressor, and the moving blades and rotating discs together form the rotor 22 of the compressor.

[0033] As can be seen in [Fig. 3], which partially shows the rotor 22 of the high-pressure compressor 8, the rotor 22 comprises annular discs 24 that rotate about the central axis X of the turbomachine and are axially separated from each other. Each disc 24 includes a radially external portion 24a for mounting blades 26, which are regularly distributed around the circumference of the corresponding disc 24. Each disc 24 further includes a rim 24b connecting the radially external portion 24a to a radially internal balancing portion 24c. The discs 24 are connected to each other by ferrules 28. The ferrules 28 can be integrally formed with some of the discs 24 and bolted to other discs 24.

[0034] In the example of [Fig. 3], the disc 24 located in the center of the figure is without a ferrule. The discs 24 located axially upstream and downstream of the central disc 24 comprise ferrules 28 having radial flanges 30 bearing on upstream faces 24d and downstream faces 24e of the central disc 24, and fixed to the central disc 24 by means of bolts 32.

[0035] Each bolt 32 has a fixing screw 34 comprising a head 34a bearing on a flange 30. Each bolt 32 further has a nut 36 cooperating with the threaded part of the corresponding fixing screw 34, the nut 36 bearing on the opposite flange 30.

[0036] The fixing screw 34 passes through openings provided in the flanges 30 and in the disc 24.

[0037] As seen in [Fig.3], the central disc 24 is equipped with a cover 40 according to the invention, allowing to cover all the fixing screws 34.

[0038] The hood 40 of [Fig.3] is shown in more detail in figures 4 to 10.

[0039] Figures 4 and 6 to 8 schematically represent a compressor disc, such as the compressor disc 24 of [Fig.3], equipped with a hood 40 according to the invention.

[0040] As can be seen in particular in figures 4 to 8, the hood 40 comprises a body 42, intended to be fixed to a compressor disc 24 by means of fixing screws 34, and a movable cover 44, mounted for rotation on the body 42.

[0041] The body 42 has a general symmetrical shape of revolution around a central axis Y coinciding with the axis of rotation of the disk 24 to which it is assembled, and coinciding with the central axis X of the turbomachine 1 in operating configuration.

[0042] In the example, the body 42 has an annular bottom wall 420 extending radially around the central axis Y. The bottom wall 420 is connected to two radially spaced circumferential walls 422, 424 extending circumferentially around the central axis Y, namely an inner circumferential wall 422 and an outer circumferential wall 424. The assembly formed by the bottom wall 420 and the inner 422 and outer 424 walls defines an annular cavity 426 extending 360° around the axis Y. This annular cavity 426 is closed by the movable cover 44, which is rotatably mounted on the body 42, near the ends of the circumferential walls 422, 424 opposite the bottom wall 420.

[0043] The bottom wall 420 is intended to rest on a surface of the disc 24, and to be clamped against the disc 24 by means of the fixing screws 34.

[0044] As can be seen in particular in [Fig.7], which is a detail view of [Fig.6], the bottom wall 420 has a plurality of holes 420a for the passage of the fixing screws 34. The annular cavity 426 of the body 42 has dimensions enabling it to contain all the heads 34a of the fixing screws 34 when they are in their tightening position.

[0045] As can be seen in Figures 4 and 6 to 8, the movable cover 44 closes the annular cavity 426 of the body 42 by presenting a smooth outer surface 440 which prevents the viscous heating observed with the known cover of [Fig. 1]. In the example, the movable cover 44 has a generally annular shape.

[0046] To allow access to the heads of the fixing screws 34 during the mounting and dismounting of the disc 24, the movable cover 44 of the hood 40 according to the invention has a limited number of screw holes 442, in this example a single screw hole 442. The number of screw holes 442 may, however, be greater than one while still retaining the advantages of the invention, and for example, equal to 2, 3, or 4. Generally, the number of screw holes will advantageously be less than or equal to 10% of the number of fixing screws required for fixing the disc 24.

[0047] The rotational movable nature of the movable cover 44 allows an operator, when tightening or loosening the fixing screws, to successively position the screw hole 442 (or one of the screw holes if there are several) opposite each fixing screw location. The screw hole(s) have a diameter allowing the passage of a fixing screw 34, as well as the passage of a screwing tool.

[0048] In the example shown in the figures, the movable cover 44 closes the annular cavity by being inserted into it. In order to guide the movable cover 44 in rotation while preventing translational movement of the movable cover along the central axis Y, the inner circumferential wall 422 and the outer circumferential wall 424 respectively comprise an inner guide element 428 and an outer guide element 430. The inner guide element 428 is a rib projecting from a radially external surface 422a of the inner circumferential wall 422, and extending circumferentially around the central axis Y, and the outer guide element is a rib projecting from a radially internal surface 424a of the outer circumferential wall 424 and extending circumferentially around the central axis Y.The movable cover 44 has an internal circumferential groove 444 and an external circumferential groove 446 cooperating respectively with the internal guide elements 428 and external guide elements 430. This cooperation between the circumferential grooves 444, 446 of the movable cover 44 and the guide elements of the body 42 ensures free rotation of the movable cover, while eliminating any freedom of movement along the central axis Y. In the example, the circumferential walls 422, 424 each have a radial rim 422b, 424b partially covering a portion of the external surface 440 of the movable cover 44.

[0049] It has been seen that the rotational mobility of the movable cover 44 allows an operator to position one or more of the screw holes at each of the fixing screws 34 during the mounting or dismounting of the disc 24. However, it is necessary to prevent any relative movement of the movable cover 44 and the body 42 under operating conditions, that is, when the cover 40 is mounted on a disc 24 of a turbomachine in operation. To this end, it is necessary to prevent the rotation of the movable cover 44 relative to the body 42 and therefore relative to the disc 24. Figures 9 and 10 show two examples of rotational locking of the movable cover 44, by means of one or more locking elements.

[0050] In the example of [Fig. 9], the locking element is one of the fixing screws 34, the head of which 34a is oversized compared to the other fixing screws 34. As can be seen in [Fig. 9], the dimensions of the screw head 34a are designed to allow it to extend to the movable cover 44, so that it can extend through the screw hole 442, thus blocking the rotation of the movable cover. Naturally, when mounting the disc 24, the fixing screw shown in [Fig. 9] must be installed last. Conversely, when removing the disc 24, this fixing screw must be removed first to allow the movable cover 44 to rotate and thus enable the removal of the other fixing screws.

[0051] In the example of [Fig. 10], a fixing screw 34 is provided, the head of which 34a is designed to cooperate with a cap 34b, forming the locking element when it is screwed onto the head of the screw 34a. As can be seen in [Fig. 10], the dimensions of the cap 34b are designed to allow it to extend to the movable cover 44, so that it can extend through the screw hole 442, thus blocking the rotation of the movable cover 44. As in the previous example, the cap 34b must be installed last when mounting the disk 24 and must be removed first when dismounting the disk 24.

[0052] When the movable cover 44 has more than one screw hole 442, a single locking element may be provided to ensure that the movable cover 44 is not rotated relative to the body 42 of the cover 40. It may also be possible to provide as many locking elements as there are screw holes 442 in order to avoid disturbances in the ventilation air caused by unclosed holes.

[0053] To allow easy assembly of the movable cover 44 and the body 42 of the hood 40, a removable body 42 is preferably provided, for example a two-part body. Figures 11 and 12 show an example of a two-part body 42.

[0054] As shown in Figures 11 and 12, the hood 40 comprises a body 42 formed of two body parts 42a, 42b and a movable cover 44 formed of two cover parts 44a, 44b. This configuration of the body 42 and the cover in two half-parts allows for easy assembly of the hood 40. Indeed, to assemble and fix the hood 40 to the disc 24, each cover part 44a, 44b is inserted into the corresponding body part 42, and then the body parts 42a, 42b are fixed to the disc 24 by rotating the cover parts 44a, 44b to successively insert and tighten the fixing screws 34.Advantageously, it is possible to join the body parts 42a, 42b before their attachment to the disc 24, by juxtaposing them and rotating the cover parts 44a, 44b so that the joining plane between the cover parts 44a, 44b is not parallel with the joining plane between the body parts 42a, 42b, as in the example of [Fig.12]. .

[0055] In the example of Figures 11 and 12, each cover portion 44a, 44b has a screw hole 442. However, it may be provided that only one of the cover portions 44a, 44b has a screw hole 442, so that the cover 40 has only one screw hole. It may also be provided that each cover portion 44a, 44b has more than one screw hole.

[0056] The elements of the hood 40 will preferably be made of a metallic alloy, for example a titanium-based alloy.

Claims

Demands

1. Hood (40) for compressor disc (24) (8) for aircraft turbomachine (1), the hood comprising: - a body (42), intended to be fixed to a compressor disc (24) by means of fixing screws (34), the body (42) having a generally symmetrical shape of revolution about a central axis (Y) and having an annular cavity (426) intended to contain all the screw heads of the fixing screws (34); - a movable cover (44) closing the annular cavity of the body (42) and having at least one screw hole (442) for the passage of a screw tool, the movable cover (44) being movable in rotation about the central axis (Y) relative to the body (42), so as to allow modification of the angular position of the screw hole(s) (442) relative to the body (42).

2. Hood (40) according to claim 1, in which the body (42) has a bottom wall (420) of annular shape, extending radially around the central axis (Y), the bottom wall (420) being connected to a first circumferential wall (422), or internal circumferential wall, and to a second circumferential wall (424), or external circumferential wall, the bottom wall (420) delimiting with the internal circumferential walls (422) and external circumferential walls (424) the annular cavity (426) of the body (42).

3. Hood (40) according to the preceding claim, wherein the movable cover (44) has a general annular shape with axis coincident with the central axis (Y) and is at least partially inserted between the inner circumferential wall (424) and the outer circumferential wall (424).

4. Hood (40) according to any one of claims 2 and 3, wherein the inner circumferential wall (422) has an inner guide element (428) and the outer circumferential wall (424) has an outer guide element (430), the guide elements (426, 430) ensuring guidance of the movable cover (44) in rotation about the central axis (Y) while preventing translational movement of the movable cover (44) in a direction parallel to the central axis (Y).

5. Hood (40) according to claim 4, wherein the internal guide element (428) is a rib projecting from a radially external surface (422a) of the internal circumferential wall (422) and extending circumferentially around the central axis (Y), and the external guide element (430) is a rib projecting from a radially internal surface (424a) of the external circumferential wall (424) and extending circumferentially around the central axis (Y), the movable cover (44) having an internal circumferential groove (444) and an external circumferential groove (446) cooperating respectively with the internal (428) and external (430) guide elements.

6. Hood (40) according to any one of the preceding claims, wherein the body (42) is formed by two body parts (42a, 42b) symmetrical with respect to a plane including the central axis (Y), and wherein the movable cover (44) is formed by two cover parts (44a, 44b) symmetrical with respect to a plane including the central axis (Y).

7. Hood according to any one of the preceding claims, having a number of screw holes (442) less than or equal to 4, and for example equal to 1.

8. Assembly of a compressor disc (24) and a cover (40) according to any one of the preceding claims, the cover (40) being fixed to the disc by means of a plurality of fixing screws (34), the screw hole or at least one screw hole (442) cooperating with a locking element (34a, 34b) in rotation of the movable cover (44).

9. Assembly of a compressor disc (24) and a cover (40) according to the preceding claim, wherein the or each rotation-locking element of the movable cover (44) is a screw head (34a) of a fixing screw (34) penetrating at least partially into the corresponding screw hole (442), or an added element (34b) on a fixing screw head (34) penetrating at least partially into the corresponding screw hole (442).

10. Aircraft turbomachine (1), comprising at least one cowling (40) according to any one of claims 1 to 7, or an assembly of a compressor disc (24) and a cowling (40) according to any one of claims 8 and 9.