System comprising a freewheel with flexible mounting
The freewheel system addresses the issue of deformation and misalignment sensitivity by using a cantilevered connection design, reducing lock-up and wear in transmission systems.
Patent Information
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- SAFRAN TRANSMISSION SYST
- Filing Date
- 2025-12-23
- Publication Date
- 2026-07-02
Smart Images
Figure FR2025051224_02072026_PF_FP_ABST
Abstract
Description
[0001] Description
[0002] Title: SYSTEM COMPRISING A FLEXIBLE MOUNTING FREEWHEEL
[0003] technical field
[0004] The present invention relates to the field of freewheeling systems, in particular those intended to constitute transmission systems, especially for equipping propulsion assemblies intended for the propulsion of aircraft.
[0005] The invention relates more particularly to such a freewheel system comprising a first member and a second member, centered around an axis, and a freewheel comprising two concentrically extending rings, of which a first ring is connected to the first member and a second ring is connected to the second member, and coupling means interposed between the two rings so as to couple the first and second members in rotation in a determined direction of rotation of one with respect to the other around the axis and to allow free relative rotation between the first and second members in a direction opposite to said determined direction of rotation.
[0006] Prior art
[0007] In a freewheel, the coupling means are, for example, clamping or wedging elements such as rollers or shims, or one or more pawls, or cams. In all cases, these coupling means are designed to adopt, in a given direction of relative rotation between the rings, a locking configuration in which these coupling means rotationally lock the two rings together, and, in the opposite direction, a free rotation configuration in which these coupling means allow the rings to rotate freely relative to each other.
[0008] Freewheels are commonly used as anti-rollback or overrunning devices, or as advance or indexing control devices. When acting as an anti-rollback device, a freewheel prevents one of the components, such as a shaft or gear, connected to one of the bushings, from rotating in the opposite direction to its normal rotation, in cases where such rotation would cause damage. When acting as an overrunning device, a freewheel allows the first component, connected to one of the bushings, to drive the second component, connected to the other bushing, until the driven component eventually rotates faster than the driving component. At this point, the freewheel disengages the two bushings, and therefore the two components, to prevent the driven component from being driven by the driven component.Finally, in a forward control function, a freewheel allows the transformation of an alternating back-and-forth movement of one of the components, attached to one of the rings, into a step-by-step rotational movement of the other component, attached to the other ring.
[0009] Such freewheeling systems are notably used as transmission systems. Documents W02015170058A1 and WO2019207256A1 illustrate examples of the use of such transmission systems within aircraft propulsion systems.
[0010] In general, freewheels are devices sensitive to deformations and misalignment, which tend to accelerate their wear and, in some cases, prevent their operation by locking the coupling means in their locking configuration and thus prohibiting any rotation of one of the rings relative to the other regardless of the direction of rotation.
[0011] Description of the invention
[0012] The invention aims to remedy this problem, at least in part. To this end, it proposes a freewheel system comprising a first component and a second component extending concentrically along an axis, and a freewheel interposed between the first and second components, wherein the freewheel comprises:
[0013] two rings extending concentrically along the axis, one of which is connected to the first organ and the other to the second organ; and coupling means interposed between the two rings so as to couple the two rings in rotation in a determined direction of rotation of one with respect to the other around the axis and to allow free relative rotation between the two rings in a direction opposite to said determined direction of rotation.
[0014] Furthermore, the system includes, for connecting the first ring to the first component, an annular support wall having:
[0015] an intermediate annular portion connected by a radial linkage structure to a body of the first organ; and
[0016] two end annular portions extending axially on either side of the intermediate annular portion, cantilevered from the radial link structure, so as to each present an annular surface radially opposite and separate from the body of the first organ.
[0017] In addition, the first ring features:
[0018] an intermediate annular portion separated from the supporting wall by an annular cavity that extends at least along the intermediate annular portion of the supporting wall; and
[0019] two annular connecting portions separated from each other by the intermediate annular portion of the first ring and rigidly connected respectively to the two end annular portions of the support wall.
[0020] Because the intermediate annular portion of the first ring is separated from the support wall by the aforementioned annular cavity, the mechanical connection between the first ring and the radial connecting structure is achieved via the end annular portions of the support wall, originating from the connecting annular portions of the first ring. This mechanical connection is therefore cantilevered relative to the radial connecting structure.
[0021] In this way, radial deformations or displacements of the annular end portions of the support wall can prevent, or at least limit, the transmission of any deformations and misalignments from the body of the first component to the first ring. The risk of unwanted freewheel lock-up can thus be limited, or even eliminated, and freewheel wear can also be reduced.
[0022] Preferably, the annular cavity extends along a portion of each of the end annular sections of the support wall. This maximizes the cantilever of the mechanical connection between the first ring and the radial connecting structure.
[0023] In preferred embodiments of the invention, the system comprises two bearings interposed between the first and second components so as to guide their rotation relative to each other, and the freewheel is housed in an axially defined annular space between the two bearings. The system can thus be particularly compact.
[0024] In preferred embodiments of the invention, the two end annular portions of the support wall have respective collars formed in radial projection towards the first ring and by which the support wall is connected to the two connecting annular portions and the first ring.
[0025] In preferred embodiments of the invention, the two annular connecting portions of the first ring extend radially in projection respectively towards the two end annular portions of the support wall, relative to the intermediate portion of the first ring.
[0026] In preferred embodiments of the invention, the radial link structure has a shape of revolution around the axis so as to continuously connect the support wall to the body of the first organ over 360 degrees.
[0027] In preferred embodiments of the invention, the two annular connecting portions of the first ring are defined axially beyond the freewheel coupling means on either side of said coupling means.
[0028] The invention also relates to an aircraft propulsion assembly, comprising a propulsion element, a turbomachine, and a freewheel system of the type defined above, said freewheel system being a transmission system in which said first element is kinematically connected to an output shaft of the turbomachine while said second element is kinematically connected to the propulsion element. In preferred embodiments of the invention, the first element is a pinion meshed with the output shaft of the turbomachine and comprising a hub which forms said body of the first element.
[0029] In preferred embodiments of the invention, the second member is a propulsion shaft surrounded by the hub of the first member and carrying said propulsion member.
[0030] The invention also relates to a method of implementing a freewheeling system of the type defined above, comprising deformations of the support wall resulting in radial displacements of respective regions of the two end annular portions of the support wall relative to the first member.
[0031] Brief description of the drawings
[0032] The invention will be better understood, and other details, advantages, and features thereof will become apparent from the following description, given by way of non-limiting example and with reference to the accompanying drawings, in which:
[0033] [Fig. 1] is a schematic axial cross-sectional view of an aircraft propulsion assembly comprising a freewheeling system according to a preferred embodiment of the invention, operating as a transmission system;
[0034] [Fig. 2] is a larger scale view of part of figure 1, illustrating the freewheeling system;
[0035] [Fig. 3] is a schematic half-view in axial section and perspective of a freewheel system according to another preferred embodiment of the invention;
[0036] [Fig. 4] is a view similar to figure 2, illustrating the path of forces within the freewheeling system.
[0037] Detailed presentation of preferred embodiments
[0038] Figure 1 schematically illustrates a freewheel system 10 comprising a first component 12 and a second component 14, centered along an axis 16. The freewheel system 10 further includes a freewheel 20 interposed between the first component 12 and the second component 14. As shown in Figure 2, the freewheel 20 comprises two rings 22, 24 extending concentrically along the axis 16. The first ring 22 is connected to the first component 12, while the second ring 24 is connected to the second component 14.Coupling means 26 are interposed between the two rings 22 and 24 so as to couple the rings 22 and 24 - and therefore the members 12 and 14 - in rotation in a determined direction of rotation of one relative to the other - for example in a determined direction of rotation of the first ring 22 relative to the second ring 24 - around the axis 16, and so as to allow free relative rotation between the rings 22 and 24 - and therefore between the members 12 and 14 - in a direction opposite to the aforementioned determined direction of rotation.
[0039] For illustrative purposes, and again with reference to Figure 1, the freewheel system 10 is shown as a transmission system within an aircraft propulsion unit 30. This propulsion unit 30 comprises a propulsion element 32, such as a propeller or a fan, and a turbomachine 34. The freewheel system 10 is, for example, arranged to act as an oversteer by transmitting the torque from an output shaft 36 of a turbomachine turbine to a propeller shaft 38 carrying the propulsion element 32, to provide propulsion for an aircraft, while allowing an overspeed of the propulsion element 32 relative to the output shaft 36 under certain flight conditions, for example during feathering of the propulsion element.
[0040] In this example, the first component 12 is a pinion meshing with an output pinion 40 carried by the turbine output shaft 36. The second component 14 can, for example, be the propeller shaft 38, or a sleeve with internal splines meshing with corresponding splines formed on the propeller shaft 38. The first component 12 thus extends around the second component 14. Therefore, the first ring 22 is an outer ring, while the second ring 24 is an inner ring. A reverse configuration is possible in other embodiments.
[0041] Of course, the freewheel system 10 can be used in other contexts, for example in association with a speed reducer as in the aforementioned document WO2019207256A1.
[0042] As shown in Figure 2, the first component 12 comprises a body 42, for example of a generally cylindrical shape, centered along the axis 16, forming a hub of the first component. This body 42 is, for example, connected by a rim 44 to an annular toothing 46 radially external to the first component 12.
[0043] The second organ 14, for example, has a wall or bearing surface 48 of generally cylindrical shape, centered along the axis 16 and surrounded by the body 42 of the first organ 12.
[0044] Two bearings 50A and 50B, such as roller bearings, are interposed between the first member 12 and the second member 14 so as to guide them in rotation relative to each other.
[0045] The free wheel 20 is housed in an annular space 52 defined axially between the two bearings 50A and 50B, which notably helps to limit the size of the system.
[0046] A connecting device is arranged to ensure the mechanical connection between the first ring 22 and the body 42. This connecting device is designed to be relatively deformable so as to avoid, as far as possible, transmitting to the freewheel 20 forces induced by any deformations and misalignments of the first component 12. In other words, the purpose of the connecting device is to avoid or limit deformations and misalignments of the first ring 22 induced by any deformations and misalignments of the first component 12.
[0047] For this purpose, the connecting device is formed of a support wall 60 of annular shape, preferably of overall cylindrical shape, and a radial connecting structure 62.
[0048] The radial connecting structure 62 extends radially from the body 42 to an annular portion 60A of the support wall 60, hereinafter referred to as the intermediate portion due to its positioning at a distance from opposite axial ends of the support wall 60. The radial connecting structure 62 thus rigidly connects the body 42 of the first component 12 to the intermediate portion 60A of the support wall 60. The radial connecting structure 62 is advantageously centered along a median transverse plane MP of the support wall 60.
[0049] The radial connecting structure 62 advantageously has a shape of revolution around the axis 16 so as to continuously connect over 360 degrees the support wall 60 to the body 42 of the first organ 12. Alternatively, the radial connecting structure 62 can be formed of an annular row of radial spacers.
[0050] The support wall 60 comprises, axially on either side of the intermediate annular portion 60A, two end annular portions 60B and 60C. These end annular portions 60B and 60C thus each extend cantilevered from the radial connecting structure 62, and therefore each present a respective annular surface 64B, 64C arranged radially opposite - and separated - from the body 42 of the first member 12. In the illustrated example, the annular surfaces 64B, 64C are radially external surfaces of the respective end annular portions 60B and 60C.
[0051] The annular end portions 60B and 60C thus exhibit a relative radial deformability or flexibility compared to the intermediate portion 60A.
[0052] Furthermore, the first ring 22 has an intermediate annular portion 22A, and two connecting annular portions 22B and 22C axially on either side of the intermediate annular portion 22A. It is of course necessary to understand that the connecting annular portions 22B and 22C are separated from each other by the intermediate annular portion 22A.
[0053] The two connecting annular portions 22B and 22C are rigidly connected respectively to the two end annular portions 60B and 60C of the support wall 60. By "rigidly connected", it is understood that the connection between the connecting annular portions 22B and 22C and the end annular portions 60B and 60C is either achieved by any suitable fixing process such as a welding, brazing or gluing process, or achieved by continuity of material.
[0054] The intermediate annular portion 22A, which is therefore defined between the two connecting annular portions 22B and 22C, has an annular surface 66, for example cylindrical in shape, radially facing and separated from the support wall 60.
[0055] For this purpose, in the example illustrated in Figure 2, the end annular portions 60B and 60C of the support wall 60 have respective flanges 68B and 68C formed in radial projection towards the first ring 22 so as to present respective annular connecting surfaces 69B, 69C through which the connection is made to the two annular connecting portions 22B and 22C of the first ring 22. The flanges 68B and 68C define between them a cylindrical surface 69A formed by the support wall 60 and arranged in radial offset with respect to the aforementioned annular connecting surfaces 69B, 69C.
[0056] An inverse configuration is also possible as shown in the example of Figure 3, in which the support wall 60 does not have the collars 68B and 68C, but has, opposite the first ring 22, a cylindrical surface 69A defined jointly by the two end annular portions 60B, 60C and the intermediate annular portion 60A of the support wall 60 and extending to the opposite axial ends of the support wall 60, while the two connecting annular portions 22B and 22C of the first ring 22 respectively form collars extending in projection towards the support wall 60 so as to be connected to the latter.
[0057] Of course, a combination of the two configurations is also possible, in which case collars 68B and 68C of the support wall 60 come to rest against corresponding collars of the first ring 22 forming respectively the two annular connecting portions 22B and 22C.
[0058] In all cases, an annular cavity 70 is thus defined between the annular surface 66 of the intermediate annular portion 22A of the first ring 22 and the intermediate portion 60A of the support wall 60. There is thus no direct rigid connection between the first ring 22 and the intermediate portion 60A of the support wall 60.
[0059] The mechanical connection between the first ring 22 and the radial connecting structure 62 - and therefore the first member 12 - is thus made via the annular end portions 60B and 60C of the support wall 60, from the annular connecting portions 22B and 22C of the first ring 22. This mechanical connection is therefore cantilevered in relation to the radial connecting structure 62.
[0060] In this way, radial deformations or displacements of the two annular end portions 60B and 60C of the support wall 60 can make it possible to avoid or at least limit the transmission of possible deformations and misalignments of the body 42 of the first member 12 to the first ring 22. The risk of undesired blocking of the coupling means 26 can thus be limited, or even avoided, as well as the wear of the free wheel 20, in general.
[0061] The annular cavity 70 preferably extends axially beyond the intermediate portion 60A of the support wall 60, on either side of this intermediate portion 60A, along a part of each of the end annular portions 60B and 60C of the support wall 60. The cantilever of the mechanical connection between the first ring 22 and the radial connecting structure 62 can thus be maximized.
[0062] The annular cavity 70 is, in particular, delimited by the aforementioned cylindrical surface 69A formed by the support wall 60.
[0063] Preferably, the two annular connecting portions 22B, 22C of the first ring 22 are defined axially beyond the coupling means 26 of the freewheel 20. Thus, the forces between the coupling means 26 and the support wall 60 necessarily pass through the intermediate portion 22A of the first ring 22. Because this intermediate portion 22A is not directly supported by the support wall 60, the intermediate portion 22A exhibits a certain radial deformability relative to the annular connecting portions 22B and 22C, which can also help to limit the risk of unwanted locking of the coupling means 26.
[0064] Furthermore, the second ring 24 is preferably rigidly connected to the second component 14, for example by welding, brazing, bonding, or any other suitable fastening technique, or by material continuity. Alternatively, the second ring 24 can be connected to the second component 14 by a connecting device similar to that described above.
[0065] In general, when implementing the freewheel system 10, the freewheel 20 allows the two parts 12 and 14 to be coupled in rotation in a determined direction of rotation of one relative to the other around the axis 16, and allows free relative rotation between the two parts 12 and 14 in a direction opposite to said determined direction of rotation.
[0066] The forces induced by the mechanical link between the first ring 22 and the first member 12 pass through the annular connecting portions 22B and 22C and through the annular end portions 60B and 60C, as shown by arrow E in figure 4.
[0067] In some cases, during the implementation of the freewheel system 10, deformations or misalignments of the first member 12 relative to the second member 14 or relative to the axis 16 induce deformations of the support wall 60 resulting in radial displacements of respective regions of one or both of the annular end portions 60B, 60C of the support wall 60, with corresponding deformations of the latter, which makes it possible to limit, or even avoid, the risks of unwanted blocking of the freewheel 20 and to limit the wear of the latter, as explained above.
Claims
Demands 1. Freewheeling system (10), comprising a first component (12) and a second component (14) which extend concentrically along an axis (16), and a freewheel (20) interposed between the first component (12) and the second component (14), in which the freewheel (20) comprises: - two rings extending concentrically along the axis (16), of which a first ring (22) is connected to the first component (12) and a second ring (24) is connected to the second component (14); and - coupling means (26) interposed between the two rings (22, 24) so as to couple the two rings (22, 24) in rotation in a determined direction of rotation of one with respect to the other around the axis (16) and to allow free relative rotation between the two rings (22, 24) in a direction opposite to said determined direction of rotation; characterized in that it comprises, for connecting the first ring (22) to the first component (12), an annular support wall (60) having: - an intermediate annular portion (60A) connected by a radial linkage structure (62) to a body (42) of the first component (12); and - two end annular portions (60B, 60C) extending axially on either side of the intermediate annular portion (60A), cantilevered from the radial link structure (62), so as to each present an annular surface (64B, 64C) radially opposite and separated from the body (42) of the first organ (12); and in that the first ring (22) presents: - an intermediate annular portion (22A) separated from the supporting wall (60) by an annular cavity (70) which extends at least along the intermediate annular portion (60A) of the supporting wall (60); and - two annular connecting portions (22B, 22C) separated from each other by the intermediate annular portion (22A) of the first ring (22) and rigidly connected respectively to the two end annular portions (60B, 60C) of the support wall (60).
2. Freewheeling system according to claim 1, in which the annular cavity (70) extends along a part of each of the end annular portions (60B, 60C) of the support wall (60).
3. A freewheeling system according to claim 1 or 2, comprising two bearings (50A, 50B) interposed between the first member (12) and the second member (14) so as to guide them in rotation relative to each other, and in which the free wheel (20) is housed in an annular space (52) defined axially between the two bearings (50A, 50B).
4. Freewheel system according to any one of claims 1 to 3, wherein the two end annular portions (60B, 60C) of the support wall (60) have respective collars (68B, 68C) formed in radial projection towards the first ring (22) and by which the support wall (60) is connected to the two connecting annular portions (22B) and (22C) of the first ring (22).
5. Freewheel system according to any one of claims 1 to 4, wherein the two annular connecting portions (22B, 22C) of the first ring (22) extend radially in projection respectively towards the two annular end portions (60B, 60C) of the support wall (60), relative to the intermediate portion (22A) of the first ring (22).
6. Freewheel system according to any one of claims 1 to 5, wherein the radial linkage structure (62) has a shape of revolution about the axis (16) so as to continuously connect over 360 degrees the support wall (60) to the body (42) of the first member (12).
7. Freewheel system according to any one of claims 1 to 6, wherein the two annular connecting portions (22B, 22C) of the first ring (22) are defined axially beyond the coupling means (26) of the freewheel (20) on either side of said coupling means (26).
8. Aircraft propulsion assembly (30), comprising a propulsion unit (32), a turbomachine (34), and a freewheel system (10) according to any one of claims 1 to 7, said freewheel system being a transmission system in which said first unit (12) is kinematically connected to an output shaft (36) of the turbomachine while said second unit (14) is kinematically connected to the propulsion unit (32).
9. Propulsion assembly according to claim 8, in which the first element (12) is a pinion meshed with the output shaft (36) of the turbomachine and comprising a hub which forms said body (42) of the first element.
10. Propulsion assembly according to claim 8 or 9, wherein the second element (14) is a propulsion shaft (38) surrounded by the hub of the first element and carrying said propulsion element (32).
11. Method of implementing a freewheeling system (10) according to any one of claims 1 to 7, comprising deformations of the support wall (60) resulting in radial displacements of respective regions of the two end annular portions (60B, 60C) of the support wall (60) relative to the first member (12).