Shrink-free centering device for centering rotor parts

Abstract

Centering device without shrinkage for centering rotor parts Centering device (1) for an inner rotor part (2) and an outer rotor part (3) concentric and centered around an axis (X-X'), fixed to each other. It comprises at least three movable cleats (5) each mounted sliding in a housing (6) along an axis orthogonal to the axis (X-X'), each housing (6) being located on an external radial face (7) of the internal rotor part (2), each housing (6) having a bottom (8) and internal walls (9) and said housings (6) being distributed radially around the axis (X-X'), each movable cleat (5) being located in the immediate vicinity of the internal walls (9) of the housing (6) in which it slides and each movable cleat (5) having a length (L) greater than the spacing distance (E) which separates it from the external rotor part (3) when it is at the bottom (8) of its housing (6). Figure to be published with the abstract: Figure 1

Description

Title of the invention: Centering device without shrinkage for centering rotor parts TECHNICAL FIELD OF THE INVENTION

[0001] The technical field of the invention is that of centering devices without hooping provided between two concentric rotor parts for centering said parts. TECHNOLOGICAL BACKGROUND OF THE INVENTION

[0002] In a rotating machine, for example a turbomachine, rotor parts are usually shrunk onto the shafts so that they retain their centering during operation to avoid generating unbalance and to provide support at certain axial stations to optimize the overall dynamic behavior.

[0003] However, shrink-fitting considerably complicates the assembly and disassembly of rotor parts. In addition, the centering effectiveness of shrink-fitting varies depending on the speed of the rotating machine and the temperature of the parts thus assembled. Indeed, a high speed can cause rotation of one rotor part relative to the other rotor part with which it is shrink-fitted, and strong thermal expansion of an outer rotor part can create unwanted play between this part and the inner rotor part onto which it is shrink-fitted.

[0004] There is therefore a need for a device for maintaining centering of concentric rotor parts, but without using hooping. Such a centering device is in particular provided in a longitudinally extending portion where the two rotor parts are at a distance from each other. Summary of the invention

[0005] In order to provide a solution to the problems mentioned above, the invention provides a centering device provided between two rotor parts and whose operating principle is based on the use of the centrifugal force of the rotor parts subject to rotation. This centrifugal force induces a radial displacement of sliding cleats, some of which become immobilized by jamming in their housing when one of the rotor parts tends to move radially, the immobilized cleats then opposing this movement of decentering / off-centering of the rotor parts relative to each other.

[0006] One aspect of the invention relates to an assembly formed of an inner rotor part, an outer rotor part and a centering device for the rotor parts, the two rotor parts being concentric and centered around an axis X-X', fixed to each other and having a longitudinally extending part where the two rotor parts are at a distance from each other, the centering device comprising at least three movable lugs each mounted to slide in a housing along an axis orthogonal to the axis X-X', each housing being located on an external radial face of the internal rotor part, in the part where the two rotor parts are at a distance from each other, each housing having a bottom and internal walls and said housings being distributed radially around the axis X-X', each movable cleat being located in the immediate vicinity of the internal walls of the housing in which it slides and each movable cleat having a length L greater than the spacing distance E which separates it from the external rotor part when it is at the bottom of its housing.

[0007] Thanks to the invention, the movable lugs slide naturally radially outwards when the rotor parts are rotated and come into abutment against the internal face of the external rotor part. If one of the rotor parts tends to move radially relative to the other in an off-center / off-axis movement, at least one movable lug is urged to move in a direction which is not radial, which tends to jam it in its housing. Said jammed lug is then immobilized in its housing and consequently opposes the off-center / off-axis movement of the rotor part relative to the other.

[0008] In addition to the characteristics which have just been mentioned in the preceding paragraph, the assembly according to one aspect of the invention may have one or more complementary characteristics among the following, considered individually or according to all technically possible combinations: • At least one housing is provided in a support mounted on the external radial face of the internal rotor part. • The support is a support ring. • The support is hollow. • At least one movable cleat mounted to slide in a housing provided in a support has at least one anti-withdrawal relief at one end located on an internal face of the movable cleat, opposite the bottom of said housing. • An anti-shrinkage relief is in the form of a shoulder. • At least one movable cleat is rigid. • At least one movable cleat and the housing in which it slides are cylindrical or parallelepiped shape. • The movable cleats and the housings in which they slide are distributed uniformly and radially around the X-X' axis. • The movable cleats and the housings in which they slide extend perpendicular to the X-X' axis.

[0009] Another aspect of the invention relates to a rotating machine comprising an assembly as previously described.

[0010] The invention and its various applications will be better understood upon reading the following description and examining the accompanying figures. BRIEF DESCRIPTION OF THE FIGURES

[0011] The figures are presented for information purposes only and do not limit the invention in any way. In the figures, the dimensions are given for illustrative purposes only, with certain distances between the parts being deliberately exaggerated for clarity.

[0012] [Fig.l] is a partial schematic view in longitudinal section of two concentric rotor parts equipped with an example of a centering device according to the invention where the cleat is shown at the bottom of its housing.

[0013] [Fig.2] is a view similar to [Fig.l] where the cleat is shown slid into abutment against the outer rotor part.

[0014] [Fig.3] is a detail view of the part circled in [Fig.2].

[0015] [Fig.4] is a schematic cross-sectional view of the elements of [Fig.l] where The set includes six movable cleats.

[0016] [Fig.5] is a view similar to [Fig.4] where the cleat is shown slid into abutment against the outer rotor part.

[0017] [Fig.6] is a view similar to [Fig.4] where the external rotor part tends to shift upwards and where the two cleats located on the right and left in the figure are subjected to non-axial movement (upwards in the figure) and are stuck in their housing, the jamming zones each being represented by a black circle.

[0018] [Fig.7] is a schematic cross-sectional view of the elements of [Fig.l] where the assembly comprises four movable cleats.

[0019] [Fig.8] is a schematic cross-sectional view of the elements of [Fig.l] where the assembly comprises three movable cleats.

[0020] [Fig.9] is a view similar to [Fig.l] illustrating an example of a variant according to the invention where the cleat is slidably mounted in a support ring housed between two support pieces.

[0021] [Fig. 10] is a view similar to [Fig.9] where the two bearing pieces are of a single piece with the inner rotor piece.

[0022] [Fig. 11] is a view similar to [Fig.9] where the two support pieces are of a single piece with the outer rotor piece.

[0023] [Fig. 12] is a view similar to [Fig.9] where the upstream support piece is of a single piece with the inner rotor piece, while the downstream support piece is of a single piece with the outer rotor piece.

[0024] [Fig. 13] is a view similar to [Fig.9] where the upstream support piece is a journal mounted on the internal rotor piece by splines and immobilized longitudinally by a threaded nut screwed onto the inner rotor part, while the downstream support part is made of a single piece with the inner rotor part. DETAILED DESCRIPTION

[0025] Unless otherwise specified, the same element appearing in different figures has a single reference.

[0026] By convention, in the present application, the terms "upstream" and "downstream" are defined with respect to the positions of the parts illustrated in the figures, the upstream being located on the left in the figures, while the downstream is located on the right. Similarly, the term "longitudinal" or "axial" corresponds to a direction parallel to the longitudinal axis X-X' along which the turbomachine extends, while the term "radial" means a direction substantially perpendicular to the longitudinal axis X-X'. Furthermore, in the present application, the terms "inner" and "outer", and "internal" and "external" are defined radially with respect to the longitudinal axis X-X'. Finally, by radial is meant a direction directed along a radius, that is to say perpendicular to the longitudinal axis X-X'.Thus, a cylindrical part extending along the longitudinal axis X-X' has an inner radial face facing the longitudinal axis X-X' of the turbomachine and an outer radial face, opposite its inner face and facing outwards. It will be noted that the longitudinal axis X-X' is the same for the rotor parts cited in the description.

[0027] As shown in [Fig.l] to [Fig.13], the invention relates to a centering device 1 provided between two concentric rotor parts 2, 3 centered around an axis X-X', namely an inner rotor part 2 and an outer rotor part 3 located around the inner rotor part 2. The invention also relates to an assembly 4 comprising two rotor parts 2, 3 and a centering device 1.

[0028] The two rotor parts 2, 3 are fixed to each other at a part not shown in the figures, and are spaced apart from each other in another part extending longitudinally and shown in the figures. The centering device 1 is provided in this other part in order to maintain the centering of the rotor parts 2, 3 between them around the axis X-X'. In the absence of this centering device 1, a decentering and / or misalignment of one of the rotor parts 2, 3 can in particular cause an imbalance in the rotating machine comprising said rotor parts 2, 3.

[0029] The two rotor parts 2, 3 are preferably parts of revolution, for example of round section.

[0030] The external rotor part 3 may for example be a disc, a ring, a journal, or any other part fixed to an internal rotor part 2 and extending longitudinally along the axis X-X' of these rotor parts 2, 3.

[0031] The inner rotor part 2 may be solid or hollow. For example, it may be a disc or a ring, but also a shaft or a rotating axis.

[0032] The centering device 1 is characterized in that it comprises movable cleats 5 each mounted in a housing 6. Each movable cleat 5 is mounted in a housing 6 so as to be able to slide therein along an axis orthogonal to the axis X-X', preferably radially along an axis perpendicular to the longitudinal axis X-X'.

[0033] Each housing 6 is located on an external radial face 7 of the internal rotor part 2, in the part where the two rotor parts 2, 3 are at a distance from each other.

[0034] The housings 6 are preferably distributed radially around the axis X-X', in particular in order to avoid imbalances in the internal rotor part 2.

[0035] As shown in [Fig.l] to [Fig.3], the housings 6 each have a bottom 8 and internal walls 9, each movable cleat 5 being located in the immediate vicinity of the internal walls 9 of the housing 6 in which it slides. These internal walls 9 are the walls against which the movable cleat 5 slides when it is in a housing 6. They could be defined as lateral internal walls 9.

[0036] The expression "in the immediate vicinity", also known as "in the immediate vicinity" designates two parts which are very close to each other, but without mutual contact. In the context of the invention, the fact that the movable cleat 5 is located in the immediate vicinity of the internal walls 9 of the housing 6 in which it slides means for example that the movable cleat 5 is located at an average distance D from said internal walls 9 such that D / P < 0.2, preferably such that D / P < 0.1 and more preferably such that D / P < 0.05, where P is the depth of the housing 6 in which the movable cleat 5 is slidably housed. These dimensions appear in [Fig. 3] where the distance D is exaggerated for reasons of clarity. This distance D corresponds to a clearance allowing the movable cleat 5 to slide in its housing 6, while allowing it to jam quickly when it is subjected to a force whose direction is different from that of the sliding.

[0037] Indeed, the lower the D / P ratio, the more quickly the movable cleat 5 stops when it is subjected to non-radial movement in order to prevent or significantly and quickly limit the decentering / misalignment of the rotor parts 2, 3 with respect to each other thanks to a phenomenon of jamming of the movable cleat 5 which is described later.

[0038] As shown in [Fig.l], each movable cleat 5 has a length L greater than the spacing distance E which separates it from the external rotor part 3 when it is at the bottom 8 of its housing 6, so in particular that it cannot come out of its housing 6. By length L of the movable cleat 5 is meant the height of said movable cleat 5, that is to say the length along which it extends substantially radially with respect to the axis X-X'. The spacing distance E is the distance located between the external face 10 of the movable cleat 5 when it is located against the bottom 8 of its housing 6 and the internal radial face 11 of the external rotor part 3 located opposite said movable cleat 5.

[0039] As shown in [Fig.2], [Fig.3], [Fig.5] and [Fig.6], when the rotor parts 2, 3 are rotated about the axis X-X', under the action of centrifugal force, the movable lugs 5 of the invention slide in the direction of the external rotor part 3 along an axis orthogonal to the axis X-X' and come into abutment against the internal radial face 11 of the external rotor part 3 located opposite said movable lugs 5.

[0040] As shown in [Fig. 6], when one of the rotating rotor parts 2, 3 tends to become off-center and / or off-center relative to the other in one direction, for example when the outer rotor part 3 tends to move upwards in [Fig. 6] (see white arrows), the movable lugs 5 which can slide substantially radially in this same direction do not oppose this off-center and / or off-center movement and come to abut against the internal radial face 11 of the outer rotor part 3 (in [Fig. 6] this is the top movable lug 5 and the bottom movable lug). The other movable lugs 5, which are not designed to slide in the direction of the off-center and / or off-center movement, are nevertheless urged to move in this direction (see black arrows), which tends to place them askew in their respective housing 6.This skewed placement tends to block these movable cleats 5 by wedging in their respective housing 6, and therefore to immobilize them by bringing the lateral face 12 of the movable cleats 5 into contact with an internal wall 9 of its respective housing 6 at the level of a wedging zone 13. These movable cleats 5 being in abutment against the internal radial face 11 of the external rotor part 3, they radially immobilize the rotor parts 2, 3 relative to each other, and prevent or greatly limit the decentering / off-centering of the rotor parts 2, 3 with respect to each other. In [Fig.6], the approximate position of each wedging zone 13 is represented by a black circle.

[0041] As shown in [Fig.8], the centering device 1 comprises at least three movable cleats 5 so that at least one movable cleat 5 is immobilized by wedging regardless of the direction in which one of the rotor parts 2, 3 tends to become off-center and / or misaligned. As shown by way of example in [Fig.4] to [Fig.7], the centering device 1 may comprise any number of movable cleats 5, as long as this number is greater than or equal to three.

[0042] As illustrated by way of example in [Fig.4] to [Fig.8], the movable cleats and the housings 6 in which they slide are preferably distributed uniformly and radially around the axis X-X'. Finally, the movable cleats 5 and the housings 6 in which they slide preferably extend perpendicularly to the axis X-X'.

[0043] At least one movable cleat 5, preferably all of them, and the housing(s) 6 in which it(they) slide(s) are preferably cylindrical or parallelepipedal in shape.

[0044] At least one movable cleat 5, preferably all of them, is rigid under normal conditions of use. The movable cleats 5 may for example be made of metal or ceramic. They must have sufficient mass to be able to slide outwards under the effect of the centrifugal force of the internal rotor part 2 subject to rotation.

[0045] According to an embodiment illustrated in [Fig.l] to [Fig.8], the housings 6 can each be in the form of a non-through recess formed in the external radial face 7 of the internal rotor part 2. This embodiment is advantageously simple, but can weaken the internal rotor part 2.

[0046] According to another embodiment illustrated in [Fig.9] to [Fig. 13], the housings 6 can each be in the form of a space delimited by two support pieces 14, namely an upstream support piece 14a and a downstream support piece 14b, these support pieces 14 being located between the rotor pieces 2, 3.

[0047] According to an additional embodiment also illustrated in [Fig. 9] to [Fig. 13], at least one housing 6, preferably all of them, is provided in a support 15 mounted on the external radial face 7 of the internal rotor part 2. The support 15 is preferably a support ring, preferably common to all the housings 6. An individual support 15 can also be provided for each housing 6.

[0048] As illustrated in [Fig.7] to [Fig.13], the support 15 may be hollow. The movable cleat 5 slidably mounted in a housing 6 provided in a hollow support 15 may have at least one anti-withdrawal relief 16, for example in the form of a shoulder, provided at one end 17 located on an internal face of said movable cleat 5, located opposite the bottom 8 of said housing 6. This movable cleat 5 projects so that the movable cleat 5 cannot come out completely from the housing 6 where it is located, in particular when handling the internal rotor part 2 before the external rotor part 3 is fixed to said internal rotor part 2.

[0049] As illustrated in [Fig.10] to [Fig.13], at least one support piece 14 may be in one piece with one of the rotor pieces 2, 3 or fixed thereto, for example by screwing or shrinking (variants not illustrated).

[0050] As illustrated in [Fig.13], where the upstream support piece 14a is in one piece with the external rotor piece 3, here in the form of a journal, at least one support piece 14 can be assembled by splines 18 with one of the rotor pieces 2, 3 and immobilized longitudinally by an immobilization piece 19, for example screwed or shrunk. By way of example, the immobilization piece 19 is a threaded nut.

[0051] Another aspect of the invention relates to a rotating machine comprising an assembly 4 of the invention, this rotating machine being able for example to be a turbomachine, a pump, a compressor, a reducer, a turbocharger, etc.

Claims

1.

2.

3.

4.

5. Claims Assembly (4) formed of an inner rotor part (2), an outer rotor part (3) and a centering device (1) for the rotor parts (2, 3), the two rotor parts (2, 3) being concentric and centered around an axis (X-X'), fixed to each other and having a longitudinally extending part where the two rotor parts (2, 3) are at a distance from each other, the centering device (1) comprising at least three sliding movable lugs (5), characterized in that each movable lug (5) is slidably mounted in a housing (6) along an axis orthogonal to the axis (X-X'), each housing (6) being located on an external radial face (7) of the inner rotor part (2), in the part where the two rotor parts (2, 3) are at a distance from each other, each housing (6) having a bottom (8) and internal walls (9) and said housings (6) being distributed radially around the axis (X-X'),each movable cleat (5) being located in the immediate vicinity of the internal walls (9) of the housing (6) in which it slides, each movable cleat (5) sliding radially in its housing (6) by a centrifugal force induced when the two rotor parts (2, 3) are rotating, from a first position in which it is located at the bottom of its housing (6) and a second position in which it is located in abutment against the external rotor part (3), and each movable cleat (5) having a length (L) greater than the spacing distance (E) which separates it from the external rotor part (3) when it is at the bottom (8) of its housing (6)., Assembly (4) according to claim 1, characterized in that at least one housing (6) is provided in a support (15) mounted on the external radial face (7) of the internal rotor part (2). Assembly (4) according to claim 2, characterized in that the support (15) is a support ring. Assembly (4) according to claim 2 or 3, characterized in that the support (15) is hollow. Assembly (4) according to claim 4, characterized in that at least one movable cleat (5) mounted to slide in a housing (6) provided in a support has at least one anti-withdrawal relief (16) at one end (17) located on an internal face of the movable cleat (5), opposite the bottom (8) of said housing (6).

6.

7.

8.

9.

10. Assembly (4) according to claim 5, characterized in that an anti-shrinkage relief (16) is in the form of a shoulder. Assembly (4) according to any one of the preceding claims, characterized in that at least one movable cleat (5) is rigid. Assembly (4) according to any one of the preceding claims, characterized in that at least one movable cleat (5) and the housing (6) in which it slides are cylindrical or parallelepipedal in shape. Assembly (4) according to any one of the preceding claims, characterized in that the movable cleats (5) and the housings (6) in which they slide are distributed uniformly and radially around the axis (X-X'). Assembly (4) according to any one of the preceding claims, characterized in that the movable cleats (5) and the housings (6) in which they slide extend perpendicular to the axis (X-X').

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