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, particularly for the rotor of a turbine, adjustable in length, comprising a locking system for the length adjustment Technical field of the invention

[0001] The present invention relates to the field of turbomachine engines comprising a motion transmission element between two moving mechanical parts.

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

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

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

[0005] Connecting rods used in kinematic systems are usually adjustable in length by relative rotation between the body and the head. The connecting rod length adjustment must also be lockable to prevent any misalignment of the connecting rod height during operation.

[0006] It is known to use a nut blocked in rotation by a cable to prevent the relative rotation of the body and the head of the connecting rod and thus the misalignment 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 cable length, which makes it difficult to control the cable tension.

[0008] Moreover, no keying prevents the cable from being put in backwards, thus locking the tightening instead of the loosening.

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

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

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

[0012] The object 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 subjected to a centrifugal force and in an environment subjected to strong vibrations.

[0013] The invention relates to a connecting rod or link, in particular for the rotor of a turbine machine, extending along an axial extension axis comprising a connecting rod body including an internal tapping or thread and a connecting rod head rotationally fixed to the connecting rod body and comprising a connecting rod including 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", we mean the dimension of the connecting rod along its axis of extension.

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

[0017] Said locking system comprises a first toothed 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 of 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 opposite direction to the axial anti-rotation projection.

[0018] When the axial lug of the first toothed washer is inserted into the axial notch of the connecting rod body, said first toothed washer is blocked from rotation relative to the connecting rod.

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

[0020] The locking system further includes a self-locking nut screwed onto the connecting rod of the connecting rod head and configured to tighten the toothed 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 de plastically formable in the radial direction under the action of an external stress on its external surface, for example a radial clamping 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 clamp, that is to say in clamping contact against, the external thread of the connecting rod.

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

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

[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 keeps the toothed washers in a locked position.

[0026] Such a self-locking nut makes it possible to obtain satisfactory performance of locking the relative rotation of the connecting rod body with respect to the connecting rod head both in an environment subjected 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 cross-section, defined by a major axis and a minor axis that are at least 20% lower than the major axis.

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

[0030] Preferably, the deformable portion of the self-locking nut has an axial length 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 comprising successively a bearing portion, a gripping portion connected to the bearing portion by a first shoulder and the deformable portion connected to the gripping portion by a second shoulder, said bearing portion being configured to bear axially on the second toothed washer in the position of locking the relative rotation of the connecting rod body with respect to the connecting rod head.

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

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

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

[0035] Preferably, the stepped internal surface of the self-locking nut includes 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 without thread and having a diameter greater 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 between 70% and 80% of the total axial length of the self-locking nut.

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

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

[0039] For example, the second surface of the gripping portion of the self-locking nut includes 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 toothed surface includes an inner diameter greater than the outer diameter of the connecting rod of the connecting rod head.

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

[0042] Preferably, the bore of the second toothed surface includes 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 includes an end portion extending from the connecting rod on the side opposite the connecting rod body and including a bore extending along a transverse axis, perpendicular to the axis of extension and further including a joint mounted in said bore.

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

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

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

[0047] For example, the connecting rod body comprises a body extending axially along the extension axis and having a first end attached to a mechanical part of the turbomachine and a second end attached 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 includes on its internal surface, the tapping or Internal thread leading to the second open end Brief description of the drawings

[0050] Other objects, features and advantages of the invention will become apparent from 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 the relative rotation between the body and the head of the connecting rod, according to an embodiment of the invention;

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

[0053] [Fig.3], is a schematic partial axial cross-sectional view 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 the relative rotation between the body and the head of the connecting rod.

[0055] Detailed description of at least one embodiment

[0056] In the following 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 horizontal transverse axis Y, perpendicular to the longitudinal axis X; and

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

[0060] In the following description, the terms "axial" and "radial" are defined with respect to the extension axis X-X' of a connecting rod or link 10.

[0061] The term "connecting rod" or "linkage" refers to any component for transmitting movement between two moving mechanical parts.

[0062] In general, the invention relates to any connecting rod configured to be adjustable in length and to be mounted in all 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 fixed in rotation to the connecting rod body 11.

[0064] The connecting rod body 11 comprises a body 1 the extending axially along the extension axis X-X' and provided with a first end 11b attached to a mechanical part of the turbomachine and a second end 1 the attached to the connecting rod head 12.

[0065] The second end 1 of the connecting rod body 11 is open.

[0066] The connecting rod body 11 includes 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 includes a cylindrical connecting rod 13, extending along the extension axis X-X' and comprising, on its external surface, the external thread 13 a.

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

[0070] The connecting rod head 12 further includes a joint 15 mounted in said bore 14a.

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

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

[0073] Alternatively, it could be provided that the connecting rod body 11 includes, at its first end, a second connecting rod head equipped 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 includes 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 includes a first toothed washer 21 mounted radially around the connecting rod 13 of the connecting rod head 10.

[0077] The first serrated 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 toothed washer 21 is intended to cooperate with an axial notch 1 the made on the connecting rod body 11 and opening onto the second open end 11c.

[0079] When the axial lug 21d of the first toothed washer 21 is inserted into the axial notch 1 of the connecting rod body 11, said first toothed washer 21 is blocked from rotation relative to the connecting rod 13.

[0080] The bore of the first toothed surface 21 includes an inner diameter greater than the outer diameter of the connecting rod 13 of the connecting rod head 12.

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

[0082] The second toothed 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 on the surface of said first lateral surface 22c and cooperating with the notches of the second lateral surface 21e of the first toothed washer 21 and by a second lateral surface 22d, here substantially flat.

[0083] The bore of the second toothed surface 22 includes an inner diameter greater than the outer diameter of the connecting rod 13 of the connecting rod head 12.

[0084] The locking system 20 further includes a self-locking nut 23 screw-mounted on the connecting rod 13 of the connecting rod head 12 and configured to clamp the toothed washers 21, 22 against each other, engaging the respective notches, as well as the axial lug 21d in the corresponding notch 1 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 comprising successively a bearing portion 25, a gripping portion 26 connected to the bearing 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" we mean any surface substantially normal to the axis of elevation of a cylindrical part, here the axis of extension of the nut 23, resulting from a sudden variation in diameter.

[0087] The stepped hollow body 24 of the nut 23 is radially delimited 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 between 2.5 mm and 4.5 mm.

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

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

[0094] The body 24 of the nut 23 has a total axial length T 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", we mean the dimension along the extension axis of the nut 23.

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

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

[0099] The second internal surface 31b includes 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 without 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 part of the support portion 25.

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

[0103] The support portion comes into axial contact against the lateral surface 21d of the second toothed 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 clamping of said external surface 30c.

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

[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 ovoid in shape, defined by a major axis Al and a minor axis A2 of shorter length than the major axis Al.

[0110] Once deformed, the deformable portion 28 of the self-locking nut 23 is tightened against the connecting rod 13 and generates a 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 include the performance of the locking system of the relative rotation of the connecting rod body 11 with respect to the connecting rod head 12 both in an environment subjected to centrifugal force and vibrations.

Claims

Demands

1. 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 the relative rotation between the connecting rod head (12) and the connecting rod body (11),said locking system (20) comprising: - a first serrated 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 locking position of 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 opposite direction to the anti-rotation axial projection (21d), and - a second serrated 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 serrated washer (21) and intended to cooperate with the notches of said first serrated washer (21) in the locking position,characterized in that: the locking system (20) further comprises a self-locking nut (23) screwed onto the connecting rod (13) of the connecting rod head (12) and configured to clamp the toothed 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 locked 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 clamps the external thread (13a) of the connecting rod (13).

2. Connecting rod (10) according to claim 1, wherein, in the deformed configuration, the deformable portion (28) of the self-locking nut (23) has a ovoid cross-section, 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, wherein the self-locking nut (23) has a total axial length (T) between 10 mm and 25 mm.

4. Connecting rod (10) according to claim 3, wherein 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, wherein 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 bear axially on the second toothed washer (22) in the position of locking the relative rotation of the connecting rod body (11) with respect to the connecting rod head (12).

6. Connecting rod (10) according to claim 5, wherein 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, wherein 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) without thread and having a diameter (E) larger than the diameter of the internal thread (31b).

8. Connecting rod (10) according to claim 7, wherein 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, wherein the bearing portion (25) of the self-locking nut (23) has an axial length (G) 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 a joint (15) mounted in said bore (14a).

Images