GUIGNOL FOR A VARIABLE TIMING DEVICE FOR A TURBOMACHINE

Abstract

A control arm (30) for a variable pitch control device of an aircraft turbomachine, this control arm being articulated respectively to a control box (12), a synchronizing bar (9), a piston rod (11) of an actuator (A), and a turnbuckle (6a), the control arm having an articulation portion to the control box comprising, on the one hand, a tab (36) and, on the other hand, a tubular portion (38) located at a distance from the tab (36), the tab and the tubular portion (38) having aligned orifices (40) configured to receive a common articulation axis of the control box (12). Figure for the abbreviation: Figure 5

Description

Title of the invention: GUIGNOL FOR A VARIABLE TIME-SETTING DEVICE FOR A TURBOMACHINE Technical field of the invention

[0001] The present invention relates to a bellcrank for a variable timing device of an aircraft turbomachine, as well as a timing device comprising such a bellcrank. Technical background

[0002] The variable-pitch stator vanes (also called VSV - acronym for Variable Stator Varies) of a turbomachine are carried by an external annular casing, generally of a compressor of the turbomachine. Each vane comprises a blade which is connected at its radially external end by a plate with a substantially circular contour to a radial cylindrical pivot which defines the axis of rotation of the vane and which is guided in rotation in a corresponding orifice of the external casing. The radially internal end of the blade of each vane generally comprises a second cylindrical pivot extending along the axis of rotation of the vane and guided in rotation in an orifice of an internal casing of the compressor.

[0003] The radially outer end of the outer pivot of each blade is connected by a lever or a connecting rod to a control ring moved in rotation around the outer casing by an actuator of the jack type or the like. The rotation of the control ring is transmitted by the connecting rods to the outer pivots of the blades and causes them to rotate around their axes.

[0004] The angular setting of the stator blades in a turbomachine is intended to adapt the geometry of the compressor to its operating point and in particular to optimize the efficiency and the pumping margin of this turbomachine and to reduce its fuel consumption in the different flight configurations.

[0005] Each of these blades is movable in rotation about its axis between a first “open” or “fully open” position in which each blade extends substantially parallel to the longitudinal axis of the turbomachine, and a second “closed” or “quasi-closed” position in which the blades are inclined relative to the axis of the turbomachine and thus reduce the air passage section through the blade stage.

[0006] Document FR-A1-2 856 424 of the applicant describes a device for variable timing of two adjacent rows of blades, which is shown in figures 1 and 2 and comprises:

[0007] - an actuator A fixed on a casing 1, - a control box 12 fixed to the casing 1, - control rings 5 ​​intended to be mounted rotatably around the casing 1 for the purpose of actuating the two rows of blades 2, - a first connecting system comprising a first bellcrank 7 with four articulations; the bellcrank 7 is articulated around a pivot 20 on the control box 12 and comprises a first arm 19 articulated on the piston rod 11, a second arm 17 articulated at one end of a synchronization bar 9, and a third arm 15 articulated at one end of a first turnbuckle 6a, one opposite end of which is articulated on a clevis 5a of the first ring 5, and - a second connection system comprising a second bellcrank 8 with three articulations; the bellcrank 8 is articulated around a pivot 21 on the control box 12 and comprises a first arm 18 articulated on an opposite end of the synchronization bar 9, and a second arm 16 articulated on one end of a second turnbuckle 6b, one opposite end of which is articulated on a clevis 5b of the second ring 5.

[0008] In the example shown in Figure 2, the arm 19 of the bell crank 7 is substantially flat. The end of the arm 19 connected to the piston rod 11 is located in a plane P which passes substantially through the middle of the axis 23 of articulation of this end. This plane P also passes through the opposite end of the arm 19 connected to the pivot 20.

[0009] However, in certain configurations responding to space problems, the opposite ends of the arm 19 connecting the bellcrank 7 to the piston rod 11 are located in two parallel planes spaced from each other. In operation, this type of configuration causes significant forces in the bellcrank which can wear quickly or even break. One of the main causes of this wear is the moment generated at the pivot. Indeed, the pivot connection to the control box receives a force offset from its center of rotation.

[0010] The present invention provides a solution to this problem, which is simple, effective and economical. Summary of the invention

[0011] The present invention provides a bellcrank for a variable timing device of an aircraft turbomachine, this bellcrank comprising a single-piece body comprising a first articulation part configured to be connected to a control box of the device, a second articulation part configured to be connected to a synchronization bar of the device, a third articulation part configured to be connected to a piston rod of an actuator of the device, and a fourth articulation part configured to be connected to a turnbuckle of the device, the third part comprising a first tab which comprises a first orifice configured to receive an articulation axis of the piston rod and which extends in a plane P substantially perpendicular to the axis of this orifice, characterized in that the first part comprises a second tab extending substantially in said plane P, and a tubular portion at a distance from said plane P, the second tab and the tubular portion comprising aligned orifices which are configured to receive a common articulation axis of the control box and which are substantially parallel to the first orifice.

[0012] In the absence of the second leg, the pivot connection of the bellcrank to the control box would receive a displaced force, relative to the center of rotation passing through the middle of the tubular portion. The presence of the second leg makes it possible to take up at least part of the moment which is applied during operation at the tubular portion and the pivot, and thus to limit the stresses of force transmission in the bellcrank. The fact of not modifying or moving the articulation axes of the bellcrank makes it possible not to modify the setting law.

[0013] The puppet according to the invention may comprise one or more of the following characteristics, taken in isolation from one another or in combination with one another:

[0014] - said body comprises an L-shaped arm which comprises two substantially per branches pendicular, a first of these branches being connected to the tubular portion and the other of these branches being connected to the first and second legs;

[0015] - the body comprises third and fourth legs substantially parallel between they and said plane P, these third and fourth legs comprising first aligned orifices for receiving a common axis of articulation of said turnbuckle, and second aligned orifices for receiving another common axis of articulation of said synchronization bar;

[0016] - the tubular portion has a length greater than a distance between said third and fourth legs;

[0017] - the tubular portion is separated from the second leg by a distance greater than or equal to a thickness of this second leg.

[0018] The present invention also relates to a variable timing device for an aircraft turbomachine, comprising at least one bellcrank as described above.

[0019] Advantageously, the device is suitable for controlling at least two annular rows of fixed blades, the blades of each row being distributed around an axis inside a casing and each comprising at their radially external end a pivot defining a substantially radial axis for setting the blade, the device comprising:

[0020] - an actuator comprising a cylinder intended to be fixed on the casing and a rod of piston,

[0021] - first and second control rings intended to be rotatably mounted around of said casing, each control ring being intended to be connected by connecting rods to the pivots of the blades of one of said rows,

[0022] a control box,

[0023] - a first connection system comprising a first bell crank as defined above- above, this first bell crank being articulated respectively on the control box, on the piston rod, at one end of a synchronization bar, and at one end of a first turnbuckle, an opposite end of which is articulated on a yoke of the first ring, and

[0024] - a second connecting system comprising a second bell crank which is articulated respec tively on the control box, on an opposite end of the synchronizing bar, and on one end of a second turnbuckle, an opposite end of which is hinged on a clevis of the second ring.

[0025] Preferably, the control box comprises a housing for receiving the tubular portion of the first bell crank, this housing being delimited between two walls of the control box which are substantially parallel and which comprise mounting holes for said common axis of articulation of the control box, one of these walls being intended to be inserted between the tubular portion and the aforementioned second tab.

[0026] The present invention also relates to a turbomachine, in particular for an aircraft, comprising at least one device as described above. Brief description of the figures

[0027] The invention will be better understood and other details, characteristics and advantages of the invention will appear on reading the following description given by way of non-limiting example with reference to the appended drawings, in which:

[0028] [fig. 1] figure 1 is a partial schematic perspective view of a turbomachine;

[0029] [fig.2] figure 2 is a schematic perspective view of a wedging device variable of the turbomachine of figure 1;

[0030] [fig.3] figure 3 is a schematic perspective view of a non-planar guignol and of a control box for a variable timing device of a turbomachine;

[0031] [fig.4] figure 4 is a schematic perspective view of a wedging device variable according to the invention;

[0032] [fig.5] figure 5 is a schematic perspective view on a larger scale of a puppet of the device of figure 4;

[0033] [fig.6] figure 6 is another schematic perspective view of the guignol of the figure 5 ; and

[0034] [fig.7] Figure 7 is a graph showing the impact of the force transmitted by the actuator of the device, on the reactions at the high and low ends of a puppet. Detailed description of the invention

[0035] Figure 1 shows a part of an aircraft turbomachine and in particular of a compressor, here high pressure, of the turbomachine.

[0036] The compressor comprises stages of compression blades, each stage comprising an annular row of fixed or stator blades and an annular row of moving or rotor blades. The rows of blades extend around the same axis which is the longitudinal axis of the turbomachine.

[0037] The first row of blades, that is to say those located furthest upstream in the compressor (with reference to the flow of gases, from upstream to downstream, in the turbomachine), is called the inlet rectifier or RDE. The next row of fixed blades, located downstream, is called the stage 1 rectifier or RDI.

[0038] The blades of the RDE and RDI rows are surrounded by an annular stator casing 1 centered on the axis of the turbomachine. Only one blade 2 is shown in the drawing.

[0039] Each blade 2 comprises a blade which is connected at its radially external end by a plate with a substantially circular contour to a radial cylindrical pivot 3 which defines the axis of rotation of the blade and which is guided in rotation in a corresponding orifice of the external casing 1. The radially internal end of the blade of each blade generally comprises a second cylindrical pivot extending along the axis of rotation of the blade and guided in rotation in an orifice of an internal casing of the compressor (not shown).

[0040] The radially outer end of the outer pivot 3 of each blade is connected by a lever or a connecting rod 4 to a control ring 5 moved in rotation around the casing 1 by a variable setting device. The rotation of the ring is transmitted by the connecting rods 4 to the outer pivots 3 of the blades 2 and makes them rotate around their axes.

[0041] The timing device, better visible in Figure 2, is used for the simultaneous variable timing of the two rows RDE and RDI and comprises:

[0042] - an actuator A comprising a cylinder 10 fixed on the casing 1 and a piston rod 11, - a control box 12 fixed on the casing 1, - a first connection system comprising a first bellcrank 7 with four articulations; the bellcrank 7 is articulated around a pivot 20 on the control box 12 and comprises a first arm 19 articulated on the piston rod 11, a second arm 17 articulated at one end of a synchronization bar 9, and a third arm 15 articulated at one end of a first turnbuckle 6a, one opposite end of which is articulated on a yoke 5a of the control ring 5 of the RDE row, and - a second connection system comprising a second bellcrank 8 with three articulations; the bellcrank 8 is articulated around a pivot 21 on the control box 12 and comprises a first arm 18 articulated on an opposite end of the synchronization bar 9, and a second arm 16 articulated at one end of a second turnbuckle 6b, one opposite end of which is articulated on a yoke 5b of the control ring 5 of the RDI row.

[0043] To limit the chain of dimensions and facilitate the assembly of the assembly, the actuator A and the connection systems are carried by the control box 12 which is fixed on the casing 1. This box 12 comprises one or more lugs 12a for fixing to the casing, for example by means of the screw-nut type and comprises means 13 for fixing the cylinder 10 of the actuator A. The box 12 further comprises housings for mounting the bell cranks 7, 8 and holes for mounting the pivots 20, 21 for articulating the bell cranks, or even an additional pivot 22 for guiding the synchronization bar 9. The articulation axes of the pivots 20, 21 and of the arms of the bell cranks 7, 8 are substantially parallel.

[0044] The translation of the piston rod 11, by retraction or extension with respect to the cylinder 10, causes a rotation of the bellcrank 7 around the axis of its pivot 20. This rotation will on the one hand generate a translation of the turnbuckle 6a and therefore a rotation of the control ring 5 of the row RDE, as well as a displacement of the synchronization bar 9. This causes a rotation of the bellcrank 8 around the axis of its pivot 21, which will result in a translation of the turnbuckle 6b and therefore a rotation of the control ring 5 of the row RDI.

[0045] In the example shown in Figure 2, the arm 19 of the bell crank 7 is substantially flat. The end of the arm 19 connected to the piston rod 11 is located in a plane P which passes substantially through the middle of the axis 23 of articulation of this end. This plane P also passes through the opposite end of the arm 19 connected to the pivot 20.

[0046] However, in certain configurations responding to space requirements, the connecting bell crank of the control box 12 to the piston rod 11 has ends articulated in two planes P and P' which are parallel and spaced apart from each other, as illustrated in FIG. 3.

[0047] In operation, this type of configuration causes significant forces in the bell crank 24 which can wear quickly or even break. One of the main causes of this wear is the moment generated at the pivot 20. Indeed, the pivot connection to the control box 12 receives a force offset relative to its center of rotation located at the plane P'.

[0048] The invention proposes a solution to this problem, one embodiment of which is illustrated in Figures 4 to 6.

[0049] In this embodiment, the bell crank 30 comprises a single-piece body comprising:

[0050] - a first articulation part 30a configured to be connected to the control box 12, - a second articulation part 30b configured to be connected to the synchronization bar 9, - a third articulation part 30c configured to be connected to the piston rod 11 of the actuator A, and - a fourth articulation part 30d configured to be connected to the turnbuckle 6a.

[0051] The third part 30c comprises a first tab 32 comprising an orifice 34 configured to receive the articulation axis 22 of the piston rod 11. This tab 32 extends in the plane P which is substantially perpendicular to the axis of the orifice 34.

[0052] The first part 30a comprises, on the one hand, a second tab 36 extending substantially in the plane P, and, on the other hand, a tubular portion 38 at a distance from this plane P. The tab 36 and the tubular portion 38 comprise aligned orifices 40 which are configured to receive a common axis of articulation of the control box 12 and which forms the aforementioned pivot 20.

[0053] In the example shown, the body of the bell crank 30 comprises an L-shaped arm 42 which comprises two substantially perpendicular branches 42a, 42b. A first branch 42a is connected to the tubular portion 38 and a second branch 42b is connected to the legs 32, 36. The legs 32, 36 extend in the plane P, in substantially opposite directions.

[0054] The arm 42 therefore supports the tubular portion 38 which is kept at a distance from the tab 36. This distance J may be greater than or equal to the thickness E of the tab 36. The arm 42 is connected here to the upper end of the tubular portion 38.

[0055] The body of the bell crank 30 further comprises third and fourth legs 44, 46 substantially parallel to each other and to the plane P. These legs 44, 46 are spaced apart from each other and comprise first aligned orifices 48 for receiving a common axis 50 for articulation of the turnbuckle 6a, and second aligned orifices 52 for receiving another common axis 54 for articulation of the synchronization bar 9.

[0056] The legs 44, 46 extend here along the branch 42a of the arm 42, on the same side thereof. The leg 44 is located above the leg 46 and passes substantially through the upper end of the tubular portion 38. The leg 44 passes substantially through the middle of the tubular portion 38.

[0057] It is therefore understood that the tubular portion 38 has a length greater than the distance between the lugs 44, 46. This distance is chosen to accommodate the end of the synchronization bar 9 as well as the end of the turnbuckle 6a.

[0058] As seen in Figure 5, the control box 12 includes a housing 56 for receiving the tubular portion 38 of the bell crank 30. This housing 56 is delimited by two walls 56a, 56b of the control box 12 which are substantially parallel and which include mounting holes for the pivot 20.

[0059] The lower wall 56b is intended to be inserted between the tubular portion 38 and the tab 36 and therefore has a thickness less than the distance J. The pivot 20 passes through the orifices of the tab 36, of the tubular portion 38 and of the walls 56a, 56b.

[0060] Figure 7 shows schematically the reduction of the forces in the bellcrank 30 thanks to the invention. L corresponds to the height of the bellcrank 30 and therefore to the length of the branch 42b of the arm 42. The arrow F corresponds to the force transmitted by the piston rod 11 of the jack, the arrow RA corresponds to the reaction of the bellcrank at the upper end of the tubular portion 38, and the arrow RB corresponds to the reaction of the bellcrank as a function of the position of the lug 36 along the branch 42. The reduction of the forces in the bellcrank can be estimated via the following equilibrium equations:

[0061] - RA = Ll / L2xF RB = L / L2 x F

[0062] We therefore see that the more L1 tends towards 0 and the more L2 tends towards L, the more the reactions on the bellcrank decrease. This is what the proposed solution approaches with the tab 36 advantageously located in the plane P, that is to say with L = L2.

[0063] In a particular embodiment of the invention, L can be between 20 and 60 mm and is for example 40 mm.

Claims

Claims

1. Bell crank (30) for a variable timing device of an aircraft turbomachine, this bell crank comprising a single-piece body comprising a first articulation part (30a) configured to be connected to a control box (12) of the device, a second articulation part (30b) configured to be connected to a synchronization bar (9) of the device, a third articulation part (30c) configured to be connected to a piston rod (11) of an actuator (A) of the device, and a fourth articulation part (30d) configured to be connected to a turnbuckle (6a) of the device, the third part (30c) comprising a first tab (32) which comprises a first orifice (34) configured to receive an axis (22) of articulation of the piston rod (11) and which extends in a plane P substantially perpendicular to the axis of this orifice, characterized in that the first part (30a) comprises a second tab (36) extending substantially in said plane P,and a tubular portion (38) at a distance from said plane P, the second leg (36) and the tubular portion (38) comprising aligned orifices (40) which are configured to receive a common axis of articulation of the control box (12) and which are substantially parallel to the first orifice, the body comprising third and fourth legs (44, 46) substantially parallel to each other and to said plane P, these third and fourth legs comprising first aligned orifices (48) for receiving a common axis (50) of articulation of said turnbuckle (6a), and second aligned orifices (52) for receiving another common axis (54) of articulation of said synchronization bar (9).,

2. A bell (30) according to claim 1, wherein said body comprises an L-shaped arm (42) which comprises two substantially perpendicular branches, a first (42a) of these branches being connected to the tubular portion (38) and the other (42b) of these branches being connected to the first and second legs (32, 36).

3. A bellcrank (30) according to claim 1, wherein the tubular portion (38) has a length greater than a distance between said third and fourth legs (44, 46).

4. Guignol (30) according to one of the preceding claims, in which the tubular portion (38) is separated from the second leg (36) by a distance (J) greater than or equal to a thickness (E) of this second leg.

5. Variable timing device for an aircraft turbomachine, comprising at least one bellcrank (30) according to one of the preceding claims.

6. Device according to the preceding claim, for controlling at least two annular rows of fixed blades (2), the blades of each row being distributed around an axis inside a casing (1) and each comprising at their radially external end a pivot (3) defining a substantially radial axis for setting the blade, the device comprising: - an actuator (A) comprising a cylinder (10) intended to be fixed on the casing and a piston rod (11), - first and second control rings (5) intended to be rotatably mounted around said casing, each control ring being intended to be connected by connecting rods (4) to the pivots of the blades of one of said rows, - a control box (12), - a first connection system comprising a first bellcrank (30) as defined in one of claims 1 to 4, this first bellcrank (30) being articulated respectively on the control box, on the piston rod,at one end of a synchronization bar (9), and at one end of a first turnbuckle (6a) of which an opposite end is articulated on a yoke (5a) of the first ring, and - a second connection system comprising a second bellcrank (8) which is articulated respectively on the control box, on an opposite end of the synchronization bar, and on one end of a second turnbuckle (6b) of which an opposite end is articulated on a yoke (5b) of the second ring.,

7. Device according to the preceding claim, in which the control box (12) comprises a housing (56) for receiving the tubular portion (38) of the first bell crank (30), this housing being delimited between two walls (56a, 56b) of the control box which are substantially parallel and which comprise mounting holes for said common axis of articulation of the control box, one (56b) of these walls being intended to be inserted between the tubular portion (38) and the aforementioned second tab (36).

8. Aircraft turbomachine, comprising at least one device according to one of claims 5 to 7.

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