FR3146945A1 - BALL JOINT LINKAGE SYSTEM FOR ACTUATING A MOVING PART OF AN AIRCRAFT TURBOMACHINE - Google Patents

Abstract

The invention relates to a ball joint connection system (801) for actuating a moving part of an aircraft turbomachine. The system (801) comprises a first part (803) comprising an opening (807) and orifices (809), an axis (811) inserted into the orifices (809) and held in said orifices (809) by means of fixing means (813) and bushings (815), a second part (805), and a ball joint (819), integral with the second part (805), allowing the rotation of the second part (805) around the axis (811). Furthermore, the axis (811), the fixing means (813) and the bushings (815) are configured so that, when the system (801) is assembled, the ball joint (819) is tightened at its ends in the direction of the axis (811) so that the translation of the ball joint (819) along the axis (811) is prevented and a clearance (821) allows the axis (811) to translate in its direction. Figure for abstract: Fig. 8

Description

BALL JOINT LINKAGE SYSTEM FOR ACTUATING A MOVING PART OF AN AIRCRAFT TURBOMACHINE

The invention relates to the field of the kinematics of moving parts of an aircraft turbomachine. It relates in particular to a ball joint connection system for actuating a moving part of an aircraft turbomachine.

In an aircraft turbomachine, to regulate the flow rate of the airflow circulating in a vein and avoid the pumping phenomenon or to evacuate debris present in said vein, it is known to use variable discharge valves.

Such valves may be in the closed position and cause no change in the flow of air through the vein in which they are mounted or in the open position in which all or part of the flow is diverted to another vein through the opening.

There , from patent application WO-A1-2020/007847, shows an aircraft turbomachine 100 which extends longitudinally along an axis X.

The turbomachine 100 comprises a fan 104, an inner shroud 105 and an outer shroud 106. The fan 102 is rotated about the axis X of the turbomachine 100 in order to suck in an air flow which is separated by the inner shroud 105 between a first drive air flow of the turbomachine, called the primary flow, and a second thrust air flow, called the secondary flow. The inner shroud 105 extends substantially along the axis X of the turbomachine 100 and the outer shroud 106 extends outside the inner shroud 105.

The primary air flow extends internally to the inner shell 105 in a primary vein V1 while the secondary flow extends externally to the inner shell 105 in a secondary vein V2. The inner shell 105 and the outer shell 106 delimit the secondary vein V2 for the circulation of the secondary air flow.

The turbomachine 100 comprises a compressor 101 for accelerating the primary flow, a combustion chamber 102 for energizing it and a turbine 103 driven by the energized air flow in order to drive the compressor 101.

Typically, in an aircraft turbomachine of this type, the compressor 101 comprises variable discharge valves which are configured to move between a closed position, in which circulation of the air flow from the primary vein V1 to the secondary vein V2 is prohibited, and an open position in which circulation of the air flow from the primary vein V1 to the secondary vein V2 is permitted.

There (from patent FR-B1-2982904) and the show, in an embodiment according to the prior art, the various parts which allow the movement (also referred to as kinematics), around an axis 201, of the variable discharge valves and which can be, for example, integrated into a compressor.

In this example, a control ring 203 is rotated by hydraulic cylinders 205 and is connected to a gate 207 for each variable discharge valve 209 by complex articulation devices called bell cranks (shown in more detail in ).

There shows the force transmission chain, going from a cylinder 205 to a door 207 of a variable discharge valve 209, which allows the movement of this variable discharge valve 209 and, in particular, the passage from an open position to a closed position by a rotation around the axis 201 (visible in the figure). ).

In this example, the force is transmitted from the connecting rod 205b of the cylinder 205 to a first bell crank 301 called the master bell crank. This causes the opening (or closing) of the door 207 (located on the right in the figure) by means of a connecting rod 303 (the door 207 being articulated by a hinge 305).

The force is then transmitted from the master bell crank 301 to the control ring 203 (to which all the variable discharge valves 209 are connected) and then from the control ring 203 to a second bell crank 307 called the slave bell crank. The slave bell crank 307 in turn causes the door 207 of a variable discharge valve 209 (located on the left on the ) via a connecting rod 309.

Furthermore, the seal 311 and the seal holder 313 on the one hand, the shoe 315 on the other hand, respectively allow good sealing of the assembly when the valves are in the closed position and optimal movement of the control ring 203 when the assembly is set in motion.

In this force transmission chain represented at the , all the circles surrounding a mechanical connection, in particular surround ball joints between different parts of the chain. Thus, many ball joints are present in this force transmission chain used to operate variable discharge valves.

Figures 4 to 6 illustrate in more detail three examples of ball joints of the force transmission chain described above.

In particular, the represents a ball joint connection system 401 between a bell crank 403 and a connecting rod 405, the represents a ball joint connection system 501 between a control ring 503 and a bell crank 505, and the represents a ball joint connection system 601 between a door 603 of a variable discharge valve and a connecting rod 605.

All these ball joint systems comprise an axle 407 inserted into through holes in one of the two parts (bell crank, control ring or door) and held in these holes by means of fixing means 409 (of the axle in the part in question) and bushings 411, positioned in these holes.

All ball joint systems also include a ball joint 413 which is integral with the other part (link, bell crank or link), which surrounds the axis 407 at an opening in the first part and which thus allows the rotation of the second part around the axis 407.

In the first two ball joint connection systems 401 and 501 described, where the axis 407 is respectively a screwed and wire-braked tapered axis and an axis with offset fixing, an operating clearance remains (intentionally) in the assembled system between the ball joint 413 and the bushings 411 which surround it so that the ball joint 413 is free to translate on the axis 407.

In the third described ball joint system 601, where the axle 407 is a smooth barrel screw which is tightened by a nut, the ball joint 413 is tightened between the two bushings 411 and no operating clearance is present in the axle/bushings/ball joint assembly, so that no translation in the direction of the axle is possible.

In the first case (systems 401 and 501), the movement of the ball joint on the axle causes wear on the axle. For example, the shows an axle 701 (with remote fixing) after its use in a ball joint connection system according to the prior art. The axle 701 clearly has a corrosion zone 703 and a wear zone 705 which are the consequence of the movements of the ball joint around the axle 701.

In the second case (system 601), the tight holding of the ball joint and the absence of operating play in the axle/bushings/ball joint assembly results in hyperstaticity of the assembly, i.e. at least one degree of mobility of the part concerned is eliminated several times (i.e. more times than necessary).

The present invention provides a solution to these drawbacks.

Thus, one objective of the invention is to reduce the sources of wear of parts of a ball joint system used for the actuation of a variable discharge valve.

For this purpose, the invention according to a first aspect relates to a ball joint connection system for actuating a moving part of an aircraft turbomachine, said system comprising:

- a first part comprising an opening and through holes positioned opposite each other, on either side of said opening;

- an axle inserted into the orifices and held in said orifices by means of fixing means and sockets, positioned in said orifices, between said axle and said first part;

- a second room; and,

- a ball joint, integral with the second part, and surrounding the axis at the opening of the first part, so as to allow the rotation of the second part around said axis,

said system being characterized in that the axis, the fixing means and the sockets are configured so that, when said system is assembled, the ball joint is tightened at its ends in the direction of the axis so that the translation of said ball joint along said axis is prevented and a clearance allows the axis to translate in its direction.

The system according to the invention may comprise one or more of the following features, taken in isolation from one another or in combination with one another:

- the moving part is a variable discharge valve, the first part is a variable discharge valve control ring and the second part is a bell crank.

- the moving part is a variable discharge valve, the first part is a gate of a variable discharge valve and the second part is a connecting rod.

- the moving part is a variable discharge valve, the first part is a bell crank and the second part is a connecting rod.

- when said system is assembled, two faces of the ball joint, located at the ends of said ball joint in the direction of the axis, bear on two faces of the sockets so that the ball joint is tightened at said ends.

- the fixing means comprise a screw head and a thread integrated into the axis, and a threaded nut complementary to said thread.
- the threaded nut is of the floating nut or barrel nut type.

- the sockets comprise a captive-type sliding socket positioned in a first orifice of the first part and a shrink-fit socket in a second orifice of the first part.

- the axis is a smooth barrel screw and the fixing means correspond to a head of said screw and a nut complementary to said screw.

The invention according to a second aspect also relates to a turbomachine comprising a control ring, a plurality of variable discharge valves and at least one system according to the first aspect.

The invention will be better understood with the aid of the following description, given solely by way of example and with reference to the appended drawings in which:

there is a schematic representation of an embodiment of a turbomachine according to the prior art;

there is a schematic representation of an embodiment of an assembly comprising a control ring and variable discharge valves according to the prior art;

there is a perspective view of an embodiment of a control ring and variable discharge valves according to the prior art;

there is a sectional view of an embodiment of a ball joint connection system according to the prior art;

there is a sectional view of an embodiment of a ball joint connection system according to the prior art;

there is a sectional view of an embodiment of a ball joint connection system according to the prior art;

there is an illustration of the wear of an axle used in a ball joint system according to the prior art;

there is a sectional view of an embodiment of a ball joint connection system according to the invention; and,

there is a sectional view of an embodiment of a ball joint connection system according to the invention.

In reference to the , we will now describe an embodiment of a ball joint connection system 801 for actuating a moving part of an aircraft turbomachine according to the invention.

In all that follows, the moving part is a variable discharge valve. However, those skilled in the art will appreciate that the invention applies to any moving part (relative to a reference point of the aircraft) of an aircraft turbomachine that must perform a movement linked to said ball joint.

The 801 system described with reference to the is a ball joint connection system between a first part 803 which is a bell crank and a second part 805 which is a connecting rod.

However, those skilled in the art will appreciate that the invention applies more generally to all ball joints which are involved in the kinematics (i.e. which contribute to their movement) of variable discharge valves.

In particular, the invention applies to all ball joint systems which are present in the force transmission chain involving (in order) the following parts: a cylinder, a connecting rod, a master bell crank, a control ring, a slave bell crank, a connecting rod and finally a door of a variable discharge valve and which lead to the actuation of the variable discharge valve.

The system 801 described in the following may be, for example, included in an aircraft turbomachine which also includes a control ring such as the control ring 203 described with reference to the and a plurality of variable relief valves such as the variable relief valves 209 described with reference to the also or still to the .
Such a system is intended to be mounted in an aircraft turbomachine (such as the turbomachine 100 described with reference to the ), for example in a compressor or between a low pressure compressor and a high pressure compressor.

In the non-limiting example shown in , the bellcrank 803 comprises an opening 807 and through orifices 809 positioned opposite each other, on either side of the opening 807. In this case, two portions 803a and 803b of the bellcrank 803 extend parallel to each other and form the sides of a U in which two orifices 809 are pierced, aligned one opposite the other and between which the opening 807 is located.

An axle 811 is inserted into the orifices 809 and held in said orifices 809 by means of, on the one hand, fixing means 813 and, on the other hand, bushings 815, positioned in the orifices 809, between the axle 811 and the bell crank 803.

In this case, in the non-limiting example shown, the axis 811 is a smooth barrel screw (which for example includes a sliding adjustment of type H7g6) and the fixing means 813 comprise a screw head 813a and a thread 813b which are integrated into the screw 811, and a threaded nut 813c (complementary to the thread 813b of the screw 811) which is a separate part.

Generally, in different embodiments, the fixing means may be integrated into the axis or separate from it. In all cases, these fixing means 813 contribute to maintaining the axis 811 in the orifices 809 when the system 801 is assembled (and potentially subjected to significant vibrations). In particular, these fixing means 813 prevent the axis 811 from exiting the orifices 809 by translation in its direction (i.e. the direction of the longitudinal extent of the axis 811).

In addition, the bushings 815 also contribute to maintaining the axle 811 in the holes 809 since the shape of the bushings is designed so that the axle 811 is tightened in the holes 809 via the bushings 815 when the system 801 is assembled.

In particular, in the embodiment shown in , the system comprises a first socket 815a which is a sliding socket, i.e. capable of translating (along its longitudinal extent) in the orifice 809 (in the upper part of the figure) in which it is positioned. In addition, it is a so-called captive socket since it has a clip 817 (which can also be a snap ring) which prevents the socket 815a from coming out of the orifice 809 once it is positioned in the orifice (in addition to a shoulder which forms the head of the socket).

Furthermore, the system 801 comprises a second sleeve 815b which is shrunk into the other orifice 809 (in the lower part of the figure). Unlike the first sleeve 815a, the second sleeve 815b cannot therefore translate once positioned in the orifice 809.

The ball joint connection system 801 also comprises a ball joint 819, secured to the connecting rod 805, and surrounding the axis 811 at the opening 807, so as to allow the rotation of the connecting rod 805 around the axis 811.

As a reminder, since this is a ball joint, the ball joint 819 not only allows rotation around the axis 811 but also rotations (or combination of these rotations) along all the axes of an orthonormal reference frame, one of the axes of which coincides with the longitudinal direction of the axis 811. The ball joint is therefore made between the bell crank 803 and the connecting rod 805 via the axis 811 and the ball joint 819.

A first specific feature of the invention lies in the fact that the axis 811, the fixing means 813 and the bushings 815 are configured so that, when the system 801 is assembled, the ball joint 819 is tightened at its ends in the direction of the axis 811 so that the translation of the ball joint 819 along the axis 811 is prevented. In other words, the shape and dimensions of these parts are designed so that once the system 801 is assembled, the translation of the ball joint 819 on the axis 811 (i.e. its sliding) is blocked.

In the non-limiting example shown, when the system 801 is assembled, two faces (flat) of the ball joint 819 which are located at its ends in the direction of the axis 811, bear on two faces (also flat) of the sockets 815 so that the ball joint 819 is clamped at its ends and therefore cannot translate in this direction on the axis 811.

A second specific feature of the invention lies in the fact that once the system 801 is assembled, a clearance (of operation) 821 allows the axis 811 to translate in its direction. In other words, the ball joint 819 cannot translate on the axis 811 but the axis 811 itself can translate in the orifices 809 of the bell crank 803 in its longitudinal direction of extension. In the non-limiting example shown, the clearance 821 is located between the head of the sleeve 815a and the edge of the orifice 809 in which it is inserted.

There shows another embodiment of the invention in which the first part 803 is a variable discharge valve control ring and the second part 805 is a bell crank. In this example, the opening 807 is located in the middle of the thickness of the control ring 803.

Further, in the embodiment shown in , the threaded nut 813c is a floating nut whereas in the embodiment shown in , the threaded nut is a barrel nut. The latter has the advantage of being captive and of not causing any protuberance at the level of the control ring.

In addition to the examples shown in Figures 8 and 9, as mentioned above, the invention applies to all ball joints present in the force transmission chain which allows one or more discharge valves to be set in motion.

For example, in another embodiment not shown, the first part may be a gate of a variable relief valve and the second part a connecting rod.

In all cases, the ball joint 819 is tightened on the axis 811 and therefore cannot slide along the axis 811 while the operating clearance 821 allows the axis 811 to slide, according to its direction, in the orifices 809 (in addition to its rotational movement on itself).

In all cases also (i.e. for all embodiments), the fact that the ball joint is tightened on the axle reduces the wear of the axle which is linked to the friction of the ball joint on it. In addition, maintaining the ability of the axle to translate according to its direction also makes it possible to reduce its wear by potentially using a larger axle (according to its longitudinal extent in particular), and also by using bushings. Thus, the axles used can be more massive and protected by bushings (used as wear parts) and have a longer service life.
Finally, the operating clearance present in the assembled system makes it possible to avoid making the system hyperstatic, i.e. to avoid adding constraints which are not necessary for the proper functioning of the ball joint.

Claims (10)

Ball joint connection system (801) for actuating a moving part of an aircraft turbomachine, said system (801) comprising:
- a first part (803) comprising an opening (807) and through orifices (809) positioned opposite each other, on either side of said opening (807);
- an axis (811) inserted into the orifices (809) and held in said orifices (809) by means of fixing means (813) and sockets (815), positioned in said orifices (809), between said axis (811) and said first part (803);
- a second room (805); and,
- a ball joint (819), integral with the second part (805), and surrounding the axis (811) at the opening (807) of the first part (803), so as to allow the rotation of the second part (805) around said axis (811),
said system (801) being characterized in that the axis (811), the fixing means (813) and the sockets (815) are configured so that, when said system (801) is assembled, the ball joint (819) is tightened at its ends in the direction of the axis (811) so that the translation of said ball joint (819) along said axis (811) is prevented and a clearance (821) allows the axis (811) to translate in its direction.
The system (801) of claim 1, wherein the movable part is a variable discharge valve, the first part (803) is a variable discharge valve control ring, and the second part (805) is a bell crank.
The system (801) of claim 1, wherein the movable part is a variable relief valve, the first part (803) is a gate of a variable relief valve, and the second part (805) is a link.
The system (801) of claim 1, wherein the moving part is a variable relief valve, the first part (803) is a bell crank, and the second part (805) is a link rod.
System (801) according to any one of the preceding claims, wherein, when said system (801) is assembled, two faces of the ball joint (819), located at the ends of said ball joint (819) in the direction of the axis (811), bear on two faces of the sockets (815) so that the ball joint (819) is tightened at said ends.
System (801) according to any one of the preceding claims, in which the fixing means (813) comprise a screw head (813a) and a thread (813b) integrated into the axis (811), and a threaded nut (813c) complementary to said thread (813b).
System (801) according to claim 6, wherein the threaded nut (813c) is of the floating nut or barrel nut type.
System (801) according to any one of the preceding claims, wherein the bushings (815) comprise a sliding bushing (815a) of captive type positioned in a first orifice (809) of the first part (803) and a bushing (815b) shrink-fitted in a second orifice (809) of the first part (803).
System (801) according to any one of the preceding claims, in which the axis (811) is a smooth barrel screw and the fixing means (813) correspond to a head of said screw and a nut complementary to said screw.
Turbomachine comprising a control ring, a plurality of variable discharge valves and at least one system (801) according to any one of claims 1 to 9.