Connecting rod, particularly for the rotor of a turbomachine, adjustable in length including a locking system for the length adjustment

Abstract

Connecting rod (10), in particular of a rotor of a turbomachine, extending along an axial extension axis (X-X') comprising a connecting rod body (11) including a tapped hole and a connecting rod head (12) rotationally fixed to the connecting rod body (11) and comprising a connecting rod (13) including an external thread (13a) cooperating with the tapped hole of the connecting rod body (11), the connecting rod (10) further comprising a system (20) for locking relative rotation between the connecting rod head (12) and the connecting rod body (11).The locking system (20) further comprises a self-locking nut (23) screw-mounted on the connecting rod (13) of the connecting rod head (12) and configured to block the relative rotation between the connecting rod body (11) and the connecting rod head (12), said self-locking nut (23) comprising a deformable portion configured to be plastically deformable in the radial direction under the action of an external load on its external surface between an initial configuration in which the deformable portion has a circular cross-section and a deformed configuration in which the deformable portion has a non-circular cross-section and clamps the external thread (13a) of the connecting rod (13). Figure for the abbreviation: [Fig 2].

Description

Title of the invention: Connecting rod, in particular for the rotor of a turbomachine, adjustable in length comprising a length adjustment locking system Technical field of the invention

[0001] The present invention relates to the field of turbomachine engines comprising a member for transmitting movement between two moving mechanical parts.

[0002] More particularly, the invention relates to a connecting rod or rod mounted on an element of the rotor of the turbomachine, in particular a connecting rod connected to a discharge valve, called "variable bleed valve", acronym VBV in English terms of a discharge vein duct of a turbomachine, the role of which is to regulate the flow rate at the inlet of a compressor of the turbomachine, or a connecting rod connected to a blade of the stator or variable-pitch rectifier, called "variable stator vane", acronym VSV in English terms.

[0003] The invention also relates to a so-called pitch control connecting rod capable of transmitting the movements of a swashplate to blade sleeves of the turbomachine.

[0004] Generally speaking, the connecting rod according to the invention is mounted in all the kinematic systems of the turbomachine where a cylinder must transmit movement to mechanical parts. State of the prior art

[0005] The connecting rods used in kinematic systems are usually adjustable in length by relative rotation between the body and the head. The adjustment of the length of the connecting rod must, moreover, be able to be locked in order to avoid any misadjustment of the height of said connecting rod during operation.

[0006] It is known to use a nut locked in rotation by a cable to prevent the relative rotation of the body and the head of the connecting rod and thus the adjustment of the height of the connecting rod.

[0007] However, such a system for locking the relative rotation of the body and the head of the connecting rod is difficult to implement because of the short length of the cable, which makes it complicated to control the tension of the cable.

[0008] In addition, there is no keying to prevent the cable from being put in upside down, thus locking the tightening instead of loosening.

[0009] Finally, such a locking system is not satisfactory when it is subjected to a centrifugal force generated by the rotation of the rotor of a turbomachine.

[0010] There is a need to improve the relative rotation locking systems of the body and head of a connecting rod or connecting rod. Statement of the invention

[0011] The present invention therefore aims to overcome the aforementioned drawbacks.

[0012] The aim of the invention is therefore to propose a system for locking the relative rotation of the body and the head of a connecting rod capable of effectively locking said rotation both in an environment subject to centrifugal force and in an environment subject to strong vibrations.

[0013] The subject of the invention is a connecting rod or connecting rod, in particular for the rotor of a turbomachine, extending along an axial extension axis comprising a connecting rod body comprising an internal tapping or thread and a connecting rod head integral in rotation with the connecting rod body and comprising a connecting rod comprising an external thread cooperating with the tapping of the connecting rod body.

[0014] In other words, the axial length between the connecting rod head and the connecting rod body is adjustable by relative rotation between the connecting rod head and the connecting rod body.

[0015] By "length" is meant the dimension of the connecting rod along its extension axis.

[0016] The connecting rod further comprises a system for locking the relative rotation between the connecting rod head and connecting rod body.

[0017] Said locking system comprises a first notched washer mounted radially around the connecting rod of the connecting rod head and comprising an axial projection or anti-rotation lug intended to cooperate with a corresponding notch on the connecting rod body in a position for locking the relative rotation of the connecting rod body with respect to the connecting rod head and a plurality of axial notches extending in the direction opposite to the anti-rotation axial projection.

[0018] When inserting the axial lug of the first notched washer into the axial notch of the connecting rod body, said first notched washer is locked in rotation relative to the connecting rod.

[0019] Said locking system further comprises a second notched washer mounted radially around the connecting rod of the connecting rod head and comprising a plurality of axial notches extending towards the first notched washer and intended to cooperate with the notches of said first notched washer in the locking position.

[0020] The locking system further comprises a self-locking nut mounted by screwing onto the connecting rod of the connecting rod head and configured to tighten the notched washers against each other, engaging the respective notches, as well as the axial lug in the corresponding notch provided on the connecting rod body and to block the relative rotation between the connecting rod body and the connecting rod head in the locking position.

[0021] Said self-locking nut comprises a deformable portion configured to be deformed plastically formable in the radial direction under the action of an external stress on its external surface, for example a radial tightening of said external surface, between an initial configuration in which the deformable portion has a circular cross-section and a deformed configuration in which the deformable portion has a non-circular cross-section and comes to tighten, that is to say in tightening contact against, the external thread of the connecting rod.

[0022] This generates braking preventing any relative rotation of the connecting rod body with respect to the connecting rod head.

[0023] By "plastically deformable" is meant any element, by its shape or its material, configured to deform plastically under the action of an external stress without returning to its initial shape when said stress stops.

[0024] In other words, after deformation, the deformable portion retains its deformed shape.

[0025] In the deformed configuration, the self-locking nut can no longer unscrew relative to the connecting rod and holds the notched washers in a locked position.

[0026] Such a self-locking nut makes it possible to obtain satisfactory performance in locking the relative rotation of the connecting rod body with respect to the connecting rod head both in an environment subject to centrifugal force and vibrations.

[0027] Generally, the connecting rod is adjustable in length and the locking system allows the length adjustment to be locked by locking the relative rotation between the connecting rod body and the connecting rod head.

[0028] Advantageously, in the deformed configuration, the deformable portion of the self-locking nut has an ovoid-shaped cross-section, defined by a major axis and a minor axis at least 20% lower than the major axis.

[0029] For example, the self-locking nut has a total axial length of between 10 mm and 25 mm.

[0030] Preferably, the deformable portion of the self-locking nut has an axial length of between 30% and 50% of the total axial length of the self-locking nut.

[0031] Advantageously, the self-locking nut comprises a stepped hollow body extending axially along a longitudinal axis and successively comprising a bearing portion, a gripping portion connected to the bearing portion by a first shoulder and the deformable portion connected by the gripping portion by a second shoulder, said bearing portion being configured to come into axial support on the second notched washer in the position for locking the relative rotation of the connecting rod body relative to the connecting rod head.

[0032] By "shoulder" is meant any surface substantially normal to the elevation axis of a cylindrical part, here the extension axis of the nut, resulting from a variation sudden in diameter.

[0033] For example, the stepped hollow body of the self-locking nut is delimited radially by a stepped outer surface and a stepped inner surface and axially by a proximal end and a distal end opposite the proximal end, the stepped outer surface comprises a first surface forming the outer surface of the bearing portion, a second surface forming the outer surface of the gripping portion and a third surface forming the outer surface of the deformable portion.

[0034] For example, the first surface of the stepped outer surface of the self-locking nut has an outer diameter greater than the diameter of the second surface which in turn has an outer diameter greater than the diameter of the third surface.

[0035] Preferably, the stepped internal surface of the self-locking nut comprises an internal tapping or thread intended to cooperate with the external thread of the connecting rod of the connecting rod head and an internal surface devoid of thread and having a diameter larger than the diameter of the internal thread.

[0036] For example, the internal thread of the stepped internal surface of the self-locking nut extends at least along the deformable portion and the gripping portion and has an axial length of between 70% and 80% of the total axial length of the self-locking nut.

[0037] Advantageously, the support portion of the self-locking nut has an axial length of between 2.5 mm and 4.5 mm.

[0038] For example, the gripping portion of the self-locking nut has an axial length of between 2 mm and 10 mm.

[0039] For example, the second surface of the gripping portion of the self-locking nut comprises grooves intended to cooperate with a tool, for example a tightening wrench for screwing the nut onto the connecting rod.

[0040] For example, the bore of the first notched surface comprises an inner diameter greater than the outer diameter of the connecting rod of the connecting rod head.

[0041] For example, the second notched washer is radially delimited by a bore and an external surface.

[0042] Preferably, the bore of the second notched surface comprises an inner diameter greater than the outer diameter of the connecting rod of the connecting rod head.

[0043] For example, the connecting rod head further comprises an end portion extending from the connecting rod on the side opposite the connecting rod body and comprising a bore extending along a transverse axis, perpendicular to the extension axis and further comprising an articulation mounted in said bore.

[0044] For example, the joint may be a ball joint or a pivot.

[0045] The connecting rod thus makes it possible to transmit or transform a movement between two parts mobile mechanics.

[0046] Alternatively, it could be provided that the connecting rod body comprises, at its first end, a second connecting rod head provided with a second articulation.

[0047] For example, the connecting rod body comprises a body extending axially along the extension axis and provided with a first end secured to a mechanical part of the turbomachine and a second end secured to the connecting rod head.

[0048] For example, the second end of the connecting rod body is open.

[0049] For example, the connecting rod body comprises on its internal surface, the tapping or internal thread opening onto the second open end Brief description of the drawings

[0050] Other aims, characteristics and advantages of the invention will appear on reading the following description, given solely by way of non-limiting example, and made with reference to the indexed drawings in which:

[0051] [Fig.l], is a partial schematic view of a connecting rod in an unlocked position of relative rotation between the body and the head of the connecting rod, according to one embodiment of the invention;

[0052] [Fig.2], is a schematic view of the connecting rod of [Fig.2] in a locked position of relative rotation between the body and the head of the connecting rod;

[0053] [Fig.3], is a schematic view in partial axial section of the self-locking nut of the [Fig.2] ; and

[0054] [Fig.4], [Fig.5] are top views of the locking system, respectively in an unlocked position and a locked position of relative rotation between the body and the head of the connecting rod.

[0055] Detailed description of at least one embodiment

[0056] In the remainder of the description, we consider an orthonormal basis X, Y, Z, with X corresponding to an axis of extension or elongation in which we find:

[0057] - a longitudinal axis X, horizontal;

[0058] - a transverse axis Y, horizontal, perpendicular to the longitudinal axis X; and

[0059] - a vertical axis Z, orthogonal to the longitudinal axes X and transverse Y and extending from bottom to top in figures 1 and 2.

[0060] In the remainder of the description, the terms “axial” and “radial” are defined relative to the extension axis X-X' of a connecting rod or connecting rod 10.

[0061] By "connecting rod" or "link" is meant any organ for transmitting a movement between two moving mechanical parts.

[0062] Generally speaking, the invention relates to any connecting rod configured to be adjustable in length and to be mounted in all the kinematic systems of a turbomachine, in particular a turbomachine rotor.

[0063] As illustrated, the connecting rod 10 comprises a connecting rod body 11 and a connecting rod head 12 integral in rotation with the connecting rod body 11.

[0064] The connecting rod body 11 comprises a body 11a extending axially along the extension axis X-X' and provided with a first end 11b secured to a mechanical part of the turbomachine and a second end 11e secured to the connecting rod head 12.

[0065] The second end 11 of the connecting rod body 11 is open.

[0066] The connecting rod body 11 comprises on its internal surface, an internal tapping or thread (not visible in the figures) opening onto the second open end 11c.

[0067] The internal thread of the connecting rod body 11 cooperates by screwing with an external thread 13a provided on the connecting rod head 12.

[0068] As illustrated, the connecting rod head 12 comprises a cylindrical connecting rod 13, extending along the extension axis X-X' and comprising, on its external surface, the external thread 13a.

[0069] The connecting rod head 12 further comprises an end portion 14 extending from the connecting rod 13 on the side opposite the connecting rod body 11 and comprising a bore 14a extending along the transverse axis Y, perpendicular to the extension axis X-X'.

[0070] The connecting rod head 12 further comprises an articulation 15 mounted in said bore 14a.

[0071] The articulation 15 can be a ball joint or a pivot.

[0072] The connecting rod 10 thus makes it possible to transmit or transform a movement between two moving mechanical parts.

[0073] Alternatively, it could be provided that the connecting rod body 11 comprises, at its first end, a second connecting rod head provided with a second articulation.

[0074] Thanks to the cooperation between the internal thread of the connecting rod body 11 and the external thread 13a of the connecting rod head 12, the length along the extension axis X-X' of the connecting rod 10 can be adjusted by relative rotation between the connecting rod head 12 and the connecting rod body 11.

[0075] The connecting rod 10 further comprises a system 20 for locking the relative rotation between the connecting rod head 12 and the connecting rod body 11.

[0076] The locking system 20 comprises a first notched washer 21 mounted radially around the connecting rod 13 of the connecting rod head 10.

[0077] The first notched washer 21 is delimited radially by a bore (not visible in the figures) and an external surface 21b and axially by a first lateral surface 21c provided with an axial lug 21d extending axially along the extension axis. X-X' towards the connecting rod body 11 and by a second lateral surface 21e comprising a plurality of axial notches regularly distributed on the surface of said second lateral surface 21e.

[0078] The axial lug 21d of the first notched washer 21 is intended to cooperate with an axial notch 11e made on the connecting rod body 11 and opening onto the second open end 11c.

[0079] When inserting the axial lug 21d of the first notched washer 21 into the axial notch 11e of the connecting rod body 11, said first notched washer 21 is locked in rotation relative to the connecting rod 13.

[0080] The bore of the first notched surface 21 comprises an internal diameter greater than the external diameter of the connecting rod 13 of the connecting rod head 12.

[0081] The locking system 20 comprises a second notched washer 22 mounted radially around the connecting rod 13 of the connecting rod head 10. The first notched washer 21 is mounted axially between the connecting rod body 11 and the second notched washer 22.

[0082] The second notched washer 22 is delimited radially by a bore (not visible in the figures) and an external surface 22b and axially by a first lateral surface 22c comprising a plurality of axial notches regularly distributed over the surface of said first lateral surface 22c and cooperating with the notches of the second lateral surface 21e of the first notched washer 21 and by a second lateral surface 22d, here substantially planar.

[0083] The bore of the second notched surface 22 comprises an internal diameter greater than the external diameter of the connecting rod 13 of the connecting rod head 12.

[0084] The locking system 20 further comprises a self-locking nut 23 mounted by screwing onto the connecting rod 13 of the connecting rod head 12 and configured to tighten the notched washers 21, 22 against each other, engaging the respective notches, as well as the axial lug 21d in the corresponding notch 11e provided on the connecting rod body 11 and blocking the relative rotation between the connecting rod body 11 and the connecting rod head 12.

[0085] The self-locking nut 23 comprises a stepped hollow body 24 extending axially along the longitudinal axis X and successively comprising a support portion 25, a gripping portion 26 connected to the support portion by a first shoulder 27 and a deformable portion 28 connected by the gripping portion 26 by a second shoulder 29.

[0086] By “shoulder” is meant any surface substantially normal to the elevation axis of a cylindrical part, here the extension axis of the nut 23, resulting from a sudden variation in diameter.

[0087] The stepped hollow body 24 of the nut 23 is delimited radially by a stepped external surface 30 and a stepped internal surface 31 and axially by an end proximal 32 and a distal end 33 opposite the proximal end 32.

[0088] The stepped external surface 30 here comprises three surfaces 30a, 30b, 30c connected to each other by the shoulders 27, 29.

[0089] The first surface 30a forms the external surface of the support portion 25, the second surface 30b forms the external surface of the gripping portion 26 and the third surface 30c forms the external surface of the deformable portion 28.

[0090] The first surface 30a has an external diameter greater than the diameter of the second surface 30b which has an external diameter greater than the diameter of the third surface 30c.

[0091] The support portion 25 has an axial length G of between 2.5 mm and 4.5 mm.

[0092] The gripping portion 26 has an axial length H of between 2 mm and 10 mm.

[0093] The deformable portion 28 has an axial length I of between 4.5 mm and 8.5 mm.

[0094] The body 24 of the nut 23 has a total axial length T of between 10 mm and 25 mm.

[0095] For example, the axial length I of the deformable portion 28 is between 30% and 50% of the total axial length T of the nut 23.

[0096] By “axial length” is meant the dimension along the extension axis of the nut 23.

[0097] The second surface 30b of the gripping portion 26 comprises grooves intended to cooperate with a tool, for example a tightening key for screwing the nut 23 onto the connecting rod 13.

[0098] The stepped internal surface 31 here comprises two surfaces 31a, 31b connected to each other by a shoulder (not referenced).

[0099] The second internal surface 31b comprises an internal tapping or thread intended to cooperate with the external thread 13a of the connecting rod 13 of the connecting rod head 12.

[0100] The first internal surface 31a is devoid of thread and has a diameter E larger than the diameter of the second internal surface 31b.

[0101] The second internal surface 31b extends along the deformable portion 28, the gripping portion 26 and a part of the support portion 25.

[0102] The first internal surface 31a has an axial length D of between 20% and 30% of the total axial length T of the nut 23.

[0103] The support portion bears axially against the lateral surface 21d of the second notched washer 21 in the locked rotation position.

[0104] The deformable portion 28 is configured to be plastically deformable in the radial direction under the action of an external stress on the third external surface 30c, for example a radial tightening of said external surface 30c.

[0105] By "plastically deformable" is meant any element, by its shape or its material, configured to deform plastically under the action of a stress external without returning to its initial shape when said stress stops.

[0106] In other words, after deformation, the deformable portion 28 retains its deformed shape.

[0107] Figures 4 and 5 illustrate the deformable portion 28 before and after deformation.

[0108] As illustrated in [Fig.4], before deformation, the deformable portion 28 has a circular cross-section of internal diameter A.

[0109] As illustrated in [Fig.5], after deformation, the deformable portion 28 has a non-circular cross-section, here of ovoid shape, defined by a major axis A1 and a minor axis A2 of length less than the major axis A1.

[0110] Once deformed, the deformable portion 28 of the self-locking nut 23 is tightened against the connecting rod 13 and generates braking preventing any relative rotation of the connecting rod body 11 with respect to the connecting rod head 12.

[0111] The advantages of the present invention are in particular the performance of the system for locking the relative rotation of the connecting rod body 11 with respect to the connecting rod head 12 both in an environment subject to centrifugal force and vibrations.

Claims

Claims

1. Connecting rod (10), in particular for a rotor of a turbomachine, extending along an axial extension axis (X-X') comprising a connecting rod body (11) comprising a thread and a connecting rod head (12) integral in rotation with the connecting rod body (11) and comprising a connecting rod (13) comprising an external thread (13a) cooperating with the thread of the connecting rod body (11), the connecting rod (10) further comprising a system (20) for locking the relative rotation between the connecting rod head (12) and the connecting rod body (11),said locking system (20) comprising: - a first notched washer (21) mounted radially around the connecting rod (13) of the connecting rod head (10) and comprising an anti-rotation axial projection (21d) intended to cooperate with a corresponding notch (lie) on the connecting rod body (11) in a position for locking the relative rotation of the connecting rod body (11) with respect to the connecting rod head (12) and a plurality of axial notches extending in the direction opposite to the anti-rotation axial projection (21d), and - a second notched washer (22) mounted radially around the connecting rod (13) of the connecting rod head (10) and comprising a plurality of axial notches extending towards the first notched washer (21) and intended to cooperate with the notches of said first notched washer (21) in the locking position,characterized in that: the locking system (20) further comprises a self-locking nut (23) mounted by screwing onto the connecting rod (13) of the connecting rod head (12) and configured to tighten the notched washers (21, 22) against each other, engaging the respective notches, as well as the axial lug (21d) in the corresponding notch (lie) provided on the connecting rod body (11) and to block the relative rotation between the connecting rod body (11) and the connecting rod head (12) in the locking position,said self-locking nut (23) comprising a deformable portion (28) configured to be plastically deformable in the radial direction under the action of an external stress on its external surface (30c) between an initial configuration in which the deformable portion (28) has a circular cross-section and a deformed configuration in which the deformable portion (28) has a non-circular cross-section and comes to tighten the external thread (13a) of the connecting rod (13).,

2. A connecting rod (10) according to claim 1, wherein, in the deformed configuration, the deformable portion (28) of the self-locking nut (23) has a cross-section of ovoid shape, defined by a major axis (Al) and a minor axis (A2) less than the major axis (Al).

3. Connecting rod (10) according to claim 1 or 2, in which the self-locking nut (23) has a total axial length (T) of between 10 mm and 25 mm.

4. Connecting rod (10) according to claim 3, in which the deformable portion (28) of the self-locking nut (23) has an axial length (I) between 30% and 50% of the total axial length (T) of the self-locking nut (23).

5. Connecting rod (10) according to any one of the preceding claims, in which the self-locking nut (23) comprises a stepped hollow body (24) extending axially along a longitudinal axis (X) and successively comprising a bearing portion (25), a gripping portion (26) connected to the bearing portion by a first shoulder (27) and the deformable portion (28) connected by the gripping portion (26) by a second shoulder (29), said bearing portion (25) being configured to come into axial support on the second notched washer (22) in the position for locking the relative rotation of the connecting rod body (11) relative to the connecting rod head (12).

6. Connecting rod (10) according to claim 5, in which the stepped hollow body (24) of the self-locking nut (23) is delimited radially by a stepped external surface (30) and a stepped internal surface (31) and axially by a proximal end (32) and a distal end (33) opposite the proximal end (32), the stepped external surface (30) comprises a first surface (30a) forming the external surface of the bearing portion (25), a second surface (30b) forming the external surface of the gripping portion (26) and a third surface (30c) forming the external surface of the deformable portion (28).

7. Connecting rod (10) according to claim 6, in which the stepped internal surface (31) of the self-locking nut (23) comprises an internal thread (31b) intended to cooperate with the external thread (13a) of the connecting rod (13) of the connecting rod head (12) and an internal surface (31a) devoid of thread and having a diameter (E) larger than the diameter of the internal thread (31b).

8. Connecting rod (10) according to claim 7, in which the internal thread (31b) of the stepped internal surface (31) of the self-locking nut (23) extends at least along the deformable portion (28) and the gripping portion (26) and has an axial length (D) between 70% and 80% of the total axial length (T) of the self-locking nut (23).

9. Connecting rod (10) according to any one of claims 5 to 8, in which the support portion (25) of the self-locking nut (23) has an axial length (G) of between 2.5 mm and 4.5 mm.

10. Connecting rod (10) according to any one of the preceding claims, wherein the connecting rod head (12) further comprises an end portion (14) extending from the connecting rod (13) on the side opposite the connecting rod body (11) and comprising a bore (14a) extending along a transverse axis (Y), perpendicular to the extension axis (X-X') and further comprising an articulation (15) mounted in said bore (14a).

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