FR3005683A1 - PROPELLER BLADE NOT CARRIED FOR A TURBOMACHINE - Google Patents

Abstract

Non-ducted propeller blade for a turbomachine, comprising a blade connected to a foot (36) engaged in a groove (44) of complementary shape to a plate (34), and means (30) for axially retaining the foot of dawn in this groove, which are mounted on the plate upstream and downstream of the blade root, characterized in that these retaining means comprise means (40) bearing radially outwardly, relative to the axis of rotation of the helix, on means (52) complementary to the plate.

Description

TECHNICAL FIELD The present invention relates to a non-faired propeller blade for a turbomachine as well as to a propeller (s) without propped (s) comprising such a blade. STATE OF THE ART In the preferred application of the invention, although not exclusive, the blade or the blade is intended to be mounted in a turbomachine doublet propellers propulsion contrarotative or non-ducted fan, designated in English "Open rotor" or "unducted fan". However, it could also, without departing from the scope of the invention, be mounted on a conventional turboprop. As a reminder, an open rotor type turbomachine mainly comprises, along a longitudinal axis and inside a cylindrical nacelle, carried by the structure of the aircraft (like the rear part of the fuselage of an airplane), a part "Gas generator" and a "propulsion" part (only the nacelle part covering the gas generator is fixed while the nacelle parts, in which are housed the rotating housings, are rotatable). The propulsion part comprises the two coaxial and counter-rotating propellers, respectively upstream (before) and downstream (rear), which are mounted in rotary ring housings with a polygonal ring of the turbomachine and which are driven, in inverse rotation with one another, for example, by a suitable mechanism driven by a power turbine located at the outlet of the gas generator part, with the vanes of the helices extending radially outside the nacelle. To allow the optimal operation of the turbomachine according to the different flight phases encountered, the vanes of the counter-rotating propellers can rotate in the radial housings of the rings. For this, they are rotated about their respective pivot axes, by a suitable orientation system to vary the setting of the blades during flight, that is to say the pitch of the propellers. For example, the blades can vary according to the system, from + 90 ° to 30 ° for the flight phases, from + 30 ° to -30 ° for the ground and reverse phases, and to have a fast return to 90 °, in the flag position, in the event of malfunction in flight (engine failure), for which the vanes are erased relative to the direction of advance of the aircraft and offer the least possible drag.

Each blade generally comprises a foot which is engaged in a groove of complementary shape of a plate for its retention radially outwardly, relative to the axis of rotation of the helix. The plate generally comprises a cylindrical portion forming a pivot and defining a radial axis of rotation and wedging of the blade.

The groove of the plate opens axially upstream and downstream and axial retaining means of the blade root are mounted on the plate, upstream and downstream of the blade root, and cooperate with the foot to block it axially in the groove. In the current technique, the retaining means are relatively complex and comprise heavy and bulky parts that are fixed by means of the screw-nut type on the plate or even solutions where one does not distinguish the pivot of the dawn. In operation, these parts are subjected to centrifugal forces and their radial outward retention is provided by the aforementioned screws which are thus subjected to very large forces that can damage them. In case of breakage of these screws, the axial retaining parts of the blade roots are then no longer retained radially outwardly, and can therefore be detached from the plate, which is very problematic. The present invention is intended in particular to provide a simple, effective and economical solution to this problem. DESCRIPTION OF THE INVENTION The invention proposes a non-ducted propeller blade for a turbomachine, comprising a blade connected to a foot engaged in a groove of complementary shape to a plate, and axial retaining means of the blade root. in this groove, which are mounted on the plate upstream and downstream of the blade root, characterized in that these retaining means comprise bearing means radially outwardly, with respect to the axis of rotation of the blade. the helix, on complementary means of the plate. In other words, the plate of the blade comprises retaining means radially outward of the blade root retaining means. The forces to which the latter retaining means are subjected in operation, because of the centrifugal forces, are thus directly subjected to the plate. The risks of rupture and loss of axial retention means of the blade root are therefore very limited. Advantageously, the retaining means comprise an upstream lock and a downstream lock, each lock comprising a flat plate mounted in at least one recess of the plate and extending substantially perpendicularly to the longitudinal axis of the blade root. Each latch can be supported by one of these flat faces on the blade root, in the mounting position. The groove preferably comprises at each of its axial ends two recesses facing one another and in which are intended to be engaged portions of the corresponding lock. Each latch may extend transversely in the groove of the platen and include portions, such as opposed end portions, housed in the recesses of the platen. In the case where the groove is dovetail section, the recesses can be located on lateral surfaces of this groove. The plate may comprise at least one lateral, radial or axial window communicating with the or each recess for the passage of a latch and its mounting in the recess. Each window is thus configured to allow the passage through it of a lock and its mounting in the recess or recesses above.

The or each window can lead to a substantially radial side face or a radially inner face of the plate. Each lock is preferably formed in one piece. Each latch may comprise a fixing lug comprising a hole for passing a bolt locking screw in its mounting position. The screw can be screwed into a threaded hole of the plate or a wedge inserted between the blade root and the bottom of the groove. The present invention also relates to a turbomachine propeller (s) not careened (s), characterized in that the or each helix comprises at least one blade as described above.

DESCRIPTION OF THE FIGURES The invention will be better understood and other details, characteristics and advantages of the invention will become apparent on reading the following description given by way of non-limiting example with reference to the accompanying drawings, in which: FIG. 1 is a diagrammatic view in axial section of a turbomachine with coaxial and counter-rotating unchanging propellers; FIGS. 2 to 5 are partial diagrammatic perspective views of a non-ducted propeller blade according to a first embodiment of the invention; the invention, - Figures 6 and 7 are partial schematic perspective views of an alternative embodiment of a non-ducted propeller blade according to the invention, and - Figures 8 and 9 are partial schematic perspective views. of another embodiment of a non-faired propeller blade according to the invention.

DETAILED DESCRIPTION Reference is first made to FIG. 1, which schematically represents an aircraft turbomachine such as a non-faired fanless turbine engine 1, designated by the expression "open rotor" or "unducted fan". This turbine engine 1 usually comprises, from upstream to downstream in the direction of flow of the gas flow F inside a nacelle 2 of the turbine engine, a compressor part (s) 3, an annular combustion chamber 4, a part with turbines 5 whose downstream 6 drives, by means of a gearbox or epicyclic gearbox 7 and contrarotatively, two propellers 8, 9 aligned coaxially along the longitudinal axis A of the turbine engine and constituting the fan.

The propellers, namely the upstream propeller 8 and the downstream propeller 9, are arranged in radial parallel planes, perpendicular to the axis A, and rotate through the downstream turbine 6 and the gearbox 7 in directions of rotation. opposite rotation. As shown in Figure 1, the upstream propeller 8 comprises a rotating cylindrical casing 11, rotatably connected to a corresponding portion of the gearbox to rotate in one direction. This rotary casing 11 is supported by bearings on a fixed cylindrical casing of the turbine engine, bearings and fixed casing are not shown. The housing 11 terminates externally by a rotary ring-shaped hub 12 housed in the usual manner in the nacelle 2 and receiving, in cylindrical housings 13 formed radially in the side wall 14 of the hub, pivots 15 of the vanes 16 of the propeller 8. The blades thus project outwardly with respect to the nacelle. Similarly, the downstream propeller 9 comprises a rotating cylindrical housing 17, on one side rotatably connected to another part of the gear 7, to then turn in the opposite direction. This rotary casing 17, supported by bearings, terminates in a rotary ring-shaped hub 18 receiving, analogously to that previously, in cylindrical housings 19, the pivots 20 of the blades 21 of the propeller 9. In operation, and briefly, the air flow F entering the turbine engine 1 is compressed, then mixed with fuel and burned in the combustion chamber 4. The generated combustion gases then pass into the turbine part 5 and 6 to drive in reverse rotation , via the epicyclic reducer 7, the propellers 8, 9 which provide most of the thrust. The combustion gases are expelled through a nozzle 10 to increase the thrust of the turbine engine 1. Moreover, the vanes 16 and 21 of the upstream and downstream propellers are of the variable-pitch type, that is to say that they can rotate in their respective housings, around the radial geometric axes B of the cylindrical pivots by means of blade pitch control systems, so that they take, as recalled earlier, an optimal angular position according to the operating conditions of the turbine engine and the flight phases concerned.

Each blade 16, 21 comprises a blade connected at its radially inner end to a foot, of dovetail section for example, which is fitted into a groove of complementary shape of a plate which carries the pivot 15, 20 of this dawn. The present invention relates to axial retention means of the foot of each blade in its mounting groove of the plate.

It is specified that, if the invention described here refers to a turboshaft turbine engine, it can be applied to a turboprop engine as well. FIGS. 2 to 5 show a first embodiment of the invention, in which the retaining means here comprise two bolts, respectively upstream 30 and downstream 32, which are mounted on the plate 34 upstream and downstream of the foot of blade 36 and which are retained radially outwardly by the plate. Each latch 30, 32 comprises a flat plate 38 and a bracket 39, one end of which is connected to a flat face of the plate. The plate 38 has a generally trapezoidal shape whose small base or upper side 40 is rectilinear and the large base or lower side 42 is rounded convex. These bases 40, 42 are connected to each other by rectilinear lateral edges each forming an angle of between 10 and 45 ° with respect to a radial axis passing through the blade. The shape and dimensions of the plate 38 of each latch 30, 32 are determined to allow the introduction of the latch in the groove 44 of the plate, as will be described in more detail in the following.

In the mounting position and as can be seen in Figures 4 and 5, the plate 38 of each latch 30, 32 is perpendicular to the longitudinal axis C of the blade root 36 and its upper side 40 is intended to be oriented radially towards outside.

The groove 44 of the plate 34 comprises, in the vicinity of each of its axial ends, recesses 46 for mounting one of the latches 30, 32. The groove 44 is here in dovetail section and defines two lateral surfaces 48 in which the recesses 46 are formed.

In the example shown, the plate 34 comprises a cavity 50 at each end of the groove 44, each cavity 50 having a parallelepipedal shape and extending substantially transversely to the axis C. The cavity 50 extends radially on a greater part of the radial dimension of the groove 44, since its radially inner bottom, and is partially closed at its radially outer end by wall elements 52 of the plate 34. The cavity 50 passes through the lateral surfaces 48 of the groove 44 forming the aforesaid recesses 46 which are thus closed at their radially outer ends by the above-mentioned wall elements 52, respectively. The cavity 50 has a thickness along the axis C which is slightly greater than that of the latch 30, 32 corresponding. The upstream and downstream side walls of the recesses 46 define means for axially retaining the lock. Each latch 30, 32 is engaged in the corresponding recesses 46 of the plate 34 in the following manner. The lock 30, 32 is positioned upstream or downstream of the groove 44, facing it, and so that its plate 38 is oriented perpendicular to the axis C and that its leg 39 is located on the opposite side to the groove.

The latch is moved in translation along the axis C until its plate 38 engages in the cavity 50 passing through one end of the groove 44. The ends of the groove 44 thus define windows. engagement and passing locks. The latch is then displaced in radial translation outwards until it engages in the recesses 46 and is supported by its upper side 40 on the wall elements 52 of the plate. In the example shown, a longitudinal shim 54 is inserted in the groove 44, between the blade root 36 and the bottom of the groove and has a length or longitudinal dimension greater than that of the groove so that its parts of axial ends protrude axially from the groove and extend radially inside the locks. The wedge makes it possible to prestress the flanks of the blade root against the lateral bearing surfaces of the groove. The shim 54 may have a length equal to the sum of the cumulative axial dimensions of the latches 30, 32 and the blade root 36, along the axis C. The lugs 39 for fixing the latches 30, 32 comprise orifices 56 screws 58 which are screwed into tapped orifices 60 of the ends of the shim 54. The screws 58 here have a radial orientation. In operation, the latches 30, 32 are retained radially outwardly by pressing their upper sides 40 on the wall elements 52 of the plate 34, are retained axially by pressing on the upstream and downstream radial walls of the recesses 46 of the 50, and are retained laterally in the cavity 50 via the screw 58. The embodiment of Figures 6 and 7 differs from the embodiment described above especially in that the latches 130, 132 are mounted upstream and downstream of the blade root, in the aforementioned recesses of the groove 144, via slots or side windows 160 opening on lateral radial faces 162 of the plate 134. Each latch 130, 132 comprises a plate planar, generally parallelepipedal shape, which is connected at one end to a bracket 139 substantially perpendicular to the plate. Each window 160 has a radially elongated shape and corresponds substantially to a lateral outlet of the cavity described above and provided at each end of the groove 144 of the plate 134. Each window 160 therefore communicates with a housing cavity of the lock, which here is engaged in the cavity and the recesses thereof as follows. The latches 130, 132 are positioned as shown in FIG. 6. Their plates are engaged in the cavities of the plate through the windows 160 by moving the latches in translation in a direction perpendicular to the axis C and the axis. of the blade, until their fixing lugs bear laterally on the plate 134. Screws (not shown) are then mounted in the orifices 156 of the tabs 139 of the locks and screwed into tapped orifices (not shown) of the plate 134 to lock the locks in their mounting positions where they can bear by their upper edges 140 right on the aforementioned wall elements of the plate.

The variant embodiment of FIGS. 8 and 9 differs from the embodiments described above, in particular in that the locks 230, 232 are mounted upstream and downstream of the blade root, in the aforementioned recesses of the groove 244 of FIG. the plate 234, via slots or radial windows 260 opening on a radially inner face 262 of the plate. Each lock 230, 232 comprises a flat plate, generally parallelepipedal shape, which can be connected to a bracket of the aforementioned type.

Each window 160 has an elongated shape and corresponds substantially to a radial outlet towards the inside of the cavity described above and provided at each end of the groove 244 of the plate 234. Each window 260 therefore communicates with a cavity for housing the lock, which is here engaged in the cavity and the recesses thereof as follows.

The latches 230, 232 are positioned as shown in FIG. 8. They are engaged in the cavities of the plate through the windows 260 by moving the latches in radial translation outwards, until their right upper edges 240 come in radial support on the aforementioned wall elements of the plate. Screws (not shown) can then be used to lock the latches in their mounting positions.

Claims (10)

REVENDICATIONS1. Propeller blade (16, 21) for a turbomachine (1), comprising a blade connected to a foot (36) engaged in a groove (44) of complementary shape to a plate (34), and means ( 30, 32) for axial retention of the blade root in this groove, which are mounted on the plate upstream and downstream of the blade root, characterized in that these retaining means comprise means (40) of support radially outwardly, with respect to the axis of rotation of the helix, on means (52) complementary to the plate. 2. blade according to claim 1, characterized in that the retaining means comprise an upstream lock (30) and a downstream lock (32), each latch comprising a flat plate (38) mounted in at least one recess (46) of the plate (34) and extending substantially perpendicularly to the longitudinal axis (B) of the blade root (36). 3. blade according to claim 2, characterized in that the groove (44) has at each of its axial ends two recesses (46) facing one another and in which are intended to be engaged parts of the latch (30, 32) corresponding. 4. blade according to claim 3, characterized in that, the groove (44) being dovetailed section, the recesses (46) are located on lateral surfaces (48) of this groove. 5. blade according to claim 3 or 4, characterized in that the plate (34) comprises at least one side window (160), radial (260) or axial communicating with the or each recess (44) for the passage of a latch (30, 32, 130, 132, 230, 232) and its mounting in the recess. 6. blade according to claim 5, characterized in that the window (160, 260) opens on a lateral face (162) substantially radial or on a face (262) radially inner of the plate (134, 234). 7. blade according to one of claims 2 to 6, characterized in that each latch (30, 32) is formed in one piece. 8. blade according to one of claims 2 to 7, characterized in that each latch (30, 32) comprises a bracket (39) having a hole (56) for passage of a screw (58) for locking the lock in its mounting position. 9. blade according to claim 8, characterized in that the screw (58) is screwed into a hole (60) threaded with the plate (34) or a shim (54) interposed between the blade root (36) and the bottom of the groove (44). 10. Turbomachine (1) propeller (s) unsheathed (s), characterized in that the or each propeller comprises at least one blade (16, 21) according to one of the preceding claims.