FLEXIBLE COUPLINGS

Abstract

A coupling suitable for use in a flexible shaft includes a first and second shaft engagement means each having a central axis, a spacer means having a central axis, and a number of support wires. A first set of support wires each extends between the first shaft engagement means and the spacer means one or more times, the first set of support wires comprises at least one support wire, and the first and second shaft engagement means and the spacer means have a common axis (A) when the coupling means is not subject to any misalignment.

Claims

1. A coupling suitable for use in a flexible shaft comprises: a first and second shaft engagement means each having a central axis; a spacer means having a central axis; and a number of support wires, the number of support wires including a first set of support wires that each extend between the first shaft engagement means and the spacer means one or more times, the first set of support wires comprising at least one support wire; wherein the first and second shaft engagement means and the spacer means have a common axis (A) when the coupling means is not subject to any misalignment.

2. A coupling according to claim 1, wherein the number of support wires includes a second set of support wires extending between the second shaft engagement means and the spacer means one or more times, and the second set of support wires comprises at least one support wire.

3. A coupling according to claim 1, further comprising: a rigid flange extending between the spacer means and the second shaft engagement means, wherein the rigid flange is rigidly connected to or integral with the spacer means and the second shaft engagement means.

4. A coupling according to claim 1, in which at least one of the support wires has a first and second end, the first end of each of the at least one support wires is anchored to the spacer means, the second end of each of the at least one support wires is anchored to a shaft engagement means, and each of the at least one support wires each extend between the first shaft engagement means and the spacer means once.

5. A coupling according to claim 1, in which at least one of the support wires has a first and second end, the first end of each of the at least one support wires is anchored to one of the spacer means or a shaft engagement means, the second end of each of the at least one support wires is anchored to one of the spacer means or a shaft engagement means, and each of the at least one support wires each extend between the first shaft engagement means and the spacer means more than once.

6. A coupling according to claim 1, in which at least one of the support wires is in tension.

7. A coupling according to claim 1, in which each end of the support wires is anchored to the spacer means or a shaft engagement means by an anchor means, in which each of the anchor means is adapted to allow the removal and replacement of the support wire that it is anchoring without having to remove any of the other support wires.

8. A coupling according to claim 2, wherein the at least one supports wires each include two clear portion and in which one or both of the clear portions of at least one of the support wires of the first set and the clear portion of at least one of the support wires of the second set extend radially relative to the common axis (A).

9. A coupling according to claim 8, in which one or both of the clear portion of at least one of the support wires of the first set and the clear portion of at least one of the support wires of the second set are so orientated that each of the at least one support wires lie on a flat radially extending plane which is substantially perpendicular to the common axis (A), extend in a direction that is at an angle to a radial direction relative to the common axis, and that angle is an acute angle.

10. A coupling according to claim 9, in which the clear portion of at least one of the support wires of the first set and the clear portion of at least one of the support wires of the second set are so orientated that each of the at least one support wires: lies on a flat plane on which the common axis (A) sits and which extends in a radial direction relative to the common axis (A), extends in a direction that is at a second angle to a flat radially extending plane which is substantially perpendicular to the common axis (A), and that second angle is an acute angle

11. A coupling according to claim 10, in which one or both of the clear portions of at least one of the support wires of the first set and the clear portion of at least one of the support wires of the second set are so orientated that: each of the at least one support wires extend in a direction that is at a first angle to a flat plane on which the common axis (A) sits and which extends in a radial direction relative to the common axis (A), each of the at least one support wires extend in a direction that is at a second angle to a radially extending flat plane which is substantially perpendicular to the common axis (A), and the first and second angles are both acute angles.

12. A coupling according to claim 11, in which the clear portions of at least one of the support wires of the first set and/or at least one of the support wires of the second set are so orientated that each of the at least one support wires support wires extend in a direction at a third angle to a radially extending flat plane which is substantially perpendicular to the common axis (A), and that third angle is an acute angle.

13. A coupling according to claim 12, in which at least one of the support wires, the first shaft engagement means, second shaft engagement means, and the spacer means are at least partially formed from a fibre reinforced material.

14. A flexible shaft suitable for use in an aircraft comprising a number of shaft elements and a number of couplings according to claim 1.

15. A flexible shaft according to claim 14 in which the shaft elements are at least partially formed from a fibre reinforced material.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0041] The present disclosure will be further described and explained by way of example with reference to the accompanying drawings in which:

[0042] FIG. 1 shows an embodiment of an aircraft incorporating an embodiment of a coupling according to the present disclosure;

[0043] FIG. 2 shows a first embodiment of a coupling according to the present disclosure;

[0044] FIG. 3 shows a section of the coupling of FIG. 2;

[0045] FIG. 4 shows schematically a second embodiment of a coupling according to the present disclosure;

[0046] FIG. 5 shows schematically a second view of the coupling of FIG. 4;

[0047] FIG. 6 shows schematically a third embodiment of a coupling according to the present disclosure, and

[0048] FIG. 7 shows schematically a part of a fourth embodiment of a coupling according to the present disclosure.

DETAILED DESCRIPTION

[0049] With reference to FIG. 1, a helicopter 2 is provided with a main gearbox 4 for its main and tail rotors (not shown). The main gearbox 4 transmits torque to a tail rotor drive line 8 via a gearbox 6. The tail rotor drive line 8 is comprised of a number of shaft elements 10, a number of flexible couplings 12, and an intermediate gearbox 14. The couplings 12 join the ends of the shaft elements 10. In some configurations the flexible couplings 12 are integral parts with shaft elements 10.

[0050] The torque is transmitted from the main gearbox 4 to a tail rotor gearbox 16 which turns the tail rotor (not shown).

[0051] With reference to FIGS. 2 and 3, the flexible coupling 12 is comprised of a first shaft engagement means 18, a second shaft engagement means 20, a spacer means 22, and a plurality of support wires 24 (of which, for clarity, only one is labelled).

[0052] Each of the first and second shaft engagement means 18, 20 is formed from an engagement shaft 26 with an engagement flange 28 at the end of the engagement shaft 26 remote from the other of the shaft engagement means. The engagement shaft 26 and engagement flange 28 have a common central axis A. The engagement flange 28 is adapted to be attached to a similarly sized flange on the end of a shaft element 10.

[0053] At the end of the engagement shaft 26 proximal to the other end of the shaft engagement means is an anchoring zone 30. In the anchoring zone 30 are a plurality of anchor apertures 32 (again only one of which is labelled) passing through the engagement shaft 26 in a radial direction relative to common central axis A Each anchor aperture 32 is counter sunk at its radially inner end. The anchor apertures 32 are evenly spaced around the outer circumference of the engagement shaft 26 and the central axis of each anchor aperture 32 in an engagement shaft lies on a radially extending flat plane that is perpendicular to the central axis A.

[0054] The spacer means 22 is cylindrical with a central axis that lies on the common central axis A, and the radially inner face of the spacer means 22 has a radius greater than the radius of the radially outer faces of the engagement shafts 26. The spacer means 22 includes a plurality of anchor apertures 34 (again only one of which is labelled) passing through the spacer means 22 in a radial direction relative to common central axis A Each anchor aperture 34 is counter sunk at its radially outer end. The anchor apertures 34 are located in the spacer means 22 in first and second sets 36, 38 and the central axis of each anchor aperture 34 in the first set lies on a radially extending first flat plane that is perpendicular to the central axis A, and the central axis of each anchor aperture 34 in the second set lies on a second radially extending flat plane that is perpendicular to the central axis A.

[0055] The number of anchor apertures 32 in the engagement shaft 26 of the first engagement means 18 and the number of anchor apertures 34 in the first set 36 in the spacer means 22 are equal. The anchor apertures 34 in the first set 36 in the spacer means 22 are evenly spaced around the circumference of the spacer means 22, and the spacing of the anchor apertures 34 around the circumference of the spacer means 22 is such that when the first flat plane includes the central axis of the anchor apertures 32 of the first engagement means 18 each anchor aperture 34 can have a substantially common axis with an anchor aperture 32 when the pairs of anchor apertures 32, 34 are radially aligned with each other.

[0056] The same is true for the second engagement means 20 in that the number of anchor apertures 32 in the engagement shaft 26 of the second engagement means 20 and the number of anchor apertures 34 in the second set 36 in the spacer means 22 are equal. The anchor apertures 34 in the second set 36 in the spacer means 22 are evenly spaced around the circumference of the spacer means 22, and the spacing of the anchor apertures 34 around the circumference of the spacer means 22 is such that when the second flat plane includes the central axis of the anchor apertures 32 of the second engagement means 20 each anchor aperture 34 can have a common axis with an anchor aperture 32 when the pairs of anchor apertures 32, 34 are radially aligned with each other.

[0057] The first and second sets of anchor apertures 34 in the spacer means 22 are longitudinally spaced from each other at a predetermined distance. The predetermined distance is such that when the anchor apertures 32 of the first engagement means 18 lie on the first flat plane and the anchor apertures 32 of the second engagement means 20 lie on the second flat plane, the first engagement means 18 and the second engagement means 20 are separated by a predetermined distance.

[0058] Extending between the anchor apertures 32 and 34 of each pair of anchor apertures is a single pass support wire 24. That support wire 24 is anchored to spacer means 22 and engagement shaft 26 using an anchor means 40 which is configured to sit in anchor apertures 32 and 34. The support wires 24 are all tensioned to a predetermined tension.

[0059] In the embodiment of the present disclosure illustrated in FIGS. 2 and 3 the first and second engagement means 18, 20, the spacer means 22, and the support wires 24 are all formed from a carbon fibre composite material.

[0060] As may be seen from FIGS. 2 and 3, the clear portions of the support wires 24 of the coupling 12 are easily visible to a person viewing the coupling without any need for dissembling the coupling or removing it from the flexible shaft. This means that any damage to or failure of any of the wire supports is easily visible. If damage or failure occurs, then the damaged or failed support wire can be removed by cutting it and removing the support wire 24 and associated anchor means 40 from the anchor apertures 32, 34. If the anchor means 40 are reusable they may be reused with a new support wire 24, or a new support wire 24 and new anchor means 40 are used to replace the removed support wire 24 and means 40.

[0061] With reference to FIG. 7, in a similar embodiment of the present disclosure, the support wire 324 is a single multiple pass support wire that pass through all the anchor apertures 332 in the illustrated anchoring zone of the spacer element 322 and all the anchor apertures 334 in the shaft engagement means 318.

[0062] The support wire has a first end 324a which is anchored to an anchor grommet 344a which fits snugly into a first anchor aperture 334, and a second end 324b which is anchored to an anchor grommet 344b which fits snugly into a second anchor aperture 334. The first and second ends 324a, 324b of the support wire 324 are anchored into the anchor grommets 344a and 344b by a known means such as by use of an appropriate adhesive.

[0063] Between the first and second ends 324a, 324b of the support wire 324 the support wire 324 passes through an anchor grommet 344 each time it passes through an anchor aperture 332 or 334. The anchor grommets 344 are, in some embodiments, fixed to the support wire 324 to prevent longitudinal movement of the support wire 324 through the anchor aperture 332 or 334 when in use. In other embodiments the anchor grommets 344 are not fixed to the support wire 324 and as such the support wire can move longitudinally through the anchor grommets 344. In all of these embodiments the anchor grommets 344 serve to protect the support wire 324 from abrasion on the spacer element 322 or shaft engagement means 318.

[0064] It will be understood that embodiments of flexible couplings with between 2 and n support wires (where n is the number of anchor apertures 332 in the spacer element 322) can be constructed in a similar fashion to that illustrated in FIG. 7. In such embodiments each first end is anchored into an anchor grommet 344a and each second end into an anchor grommet 344b. It will be further understood that the anchor grommets 344a and 344b could be located in an anchor aperture in the spacer element instead of the shaft engagement means.

[0065] With reference to FIGS. 4 and 5, a flexible coupling 112 is schematically illustrated. The flexible coupling 112 is comprised of first and second shaft engagement means each having an engagement shaft 126. The engagement shafts 126 are coaxial with each other and spacer means 122. Each engagement shaft 126 includes anchor apertures 132A and 132B (for clarity only one of each is labelled for each engagement shaft) where the anchor apertures 132A are evenly spaced around the engagement shaft 126 along a first circumference, and the anchor apertures 132B are evenly spaced around the engagement shaft 126 along a second circumference. The first and second sets 136, 138 of anchor apertures 134 are evenly spaced around the spacer means 122. As discussed in connection with FIGS. 2 and 3 above, support wires 124 extend between pairs of anchor apertures 132, 134 and are anchored into those anchor apertures by anchor means. The difference between the coupling 112 and coupling 12 is that the support wires 124 do not all extend in a radial direction. At least some of the support wires 124 are angled to a flat plane perpendicular to the common axis A of the engagement shafts 126 and spacer means 122.

[0066] The schematically illustrated coupling 112 operates, is inspected and may be repaired in the same fashion as coupling 12 as discussed above.

[0067] With reference to FIG. 6, a flexible coupling 212 is schematically illustrated. The flexible coupling 212 is comprised of first and second shaft engagement means each having an engagement shaft 226. The engagement shafts 226 are coaxial with each other and spacer means 222. The first engagement shaft 226 includes anchor apertures 232A and 232B (for clarity only one of each is labelled) where the anchor apertures 232A are evenly spaced around the first engagement shaft 226 along a first circumference, and the anchor apertures 232B are evenly spaced around the first engagement shaft 226 along a second circumference. A set 236 of anchor apertures 234 are evenly spaced around the spacer means 222. As discussed in connection with FIGS. 2 and 3 above, support wires 224 extend between pairs of anchor apertures 232, 234 and are anchored into those anchor apertures by anchor means. The support wires 224 do not all extend in a radial direction. At least some of the support wires 224 are angled to a flat plane perpendicular to the common axis A of the engagement shafts 126 and spacer means 122.

[0068] The spacer means 222 also includes a fixed flange 242 extending between and fixed to the spacer means 222 and the engagement shaft 226 of the second engagement means. The fixed flange 242 replaces the support wires for the second engagement means.

[0069] The schematically illustrated coupling 212 operates, is inspected and may be repaired in the same fashion as coupling 12 as discussed above.

[0070] The above description is meant to be exemplary only, and one skilled in the art will recognize that changes may be made to the embodiments described without departing from the scope of the invention disclosed. Still other modifications which fall within the scope of the present invention will be apparent to those skilled in the art, in light of a review of this disclosure.

[0071] Various aspects of the fuel filters disclosed in the various embodiments may be used alone, in combination, or in a variety of arrangements not specifically discussed in the embodiments described in the foregoing and this disclosure is therefore not limited in its application to the details and arrangement of components set forth in the foregoing description or illustrated in the drawings. For example, aspects described in one embodiment may be combined in any manner with aspects described in other embodiments. Although particular embodiments have been shown and described, it will be obvious to those skilled in the art that changes and modifications may be made without departing from this invention in its broader aspects. The scope of the following claims should not be limited by the embodiments set forth in the examples, but should be given the broadest reasonable interpretation consistent with the description as a whole.