Transfer couplings

Abstract

A transfer coupling has a static component and a rotatable component arranged in axial alignment. The static component includes a first number (n1) of radially extending ports and the rotatable component has a second number (n) of radially extending ports, the radially extending ports arranged in a common circumferential plane, wherein the ports on each component are equally spaced around the component and the number of ports on a first of the components is one less than on the second of the components.

Claims

1. A transfer coupling comprising; a static component and a rotatable component arranged concentrically with the static component, the static component including a first number of radially extending ports, the radially extending ports arranged in a common circumferential plane wherein; the ports on each component are equally spaced around the component, the number of ports on a first of the components is one less than the number of ports on the second of the components, and the packing factor of ports on each of the components is at least 40%.

2. The transfer coupling as claimed in claim 1, wherein the packing factor on the first of the components is 50% or greater.

3. The transfer coupling as claimed in claim 1, wherein the first of the components is the static component and the static component sits radially outboard of the rotatable component.

4. The transfer coupling as claimed in claim 1, wherein the ports on each component are of consistent shape and size.

5. The transfer coupling as claimed in claim 1, wherein the ports on each component share the same geometry.

6. The transfer coupling as claimed in claim 5, wherein the shared geometry is axially extending slots.

7. The transfer coupling as claimed in claim 5, wherein the shared geometry is round holes.

8. The transfer coupling as claimed in claim 1, wherein the ports on one or both components are arranged at an incline to a radius of the component.

9. A planetary gear box, wherein a rotating shaft of the planetary gear box is coupled to a radially outboard static housing of the planetary gear box by the transfer coupling of the planetary gearbox in accordance with claim 1.

10. A gas turbine engine having the planetary gear box of the form recited in claim 9.

11. A transfer coupling comprising; a static component and a rotatable component arranged concentrically with the static component, the static component including a first number of radially extending ports, the rotatable component comprising a second number of radially extending ports, the radially extending ports arranged in a common circumferential plane wherein; the ports on each component are equally spaced around the component, the number of ports on a first of the components is one less than the number of ports on the second of the components, and the packing factor on the first of the components is 50% or greater, wherein the ports on each component share the same geometry.

12. The transfer coupling as claimed in claim 11, wherein the first of the components is the static component and the static component sits radially outboard of the rotatable component.

13. The transfer coupling as claimed in claim 11, wherein the shared geometry is axially extending slots.

14. The transfer coupling as claimed in claim 11, wherein the shared geometry is round holes.

15. A transfer coupling comprising; a static component and a rotatable component arranged concentrically with the static component, the static component including a first number of radially extending ports, the rotatable component comprising a second number of radially extending ports, the radially extending ports arranged in a common circumferential plane wherein; the ports on each component are equally spaced around the component, the number of ports on a first of the components is one less than the number of ports on the second of the components, and a majority of the first number of radially extending ports circumferentially overlaps with the second number of radially extending regardless of an orientation of the rotatable component relative to the static component.

16. The transfer coupling as claimed in claim 15, wherein the first of the components is the static component and the static component sits radially outboard of the rotatable component.

17. The transfer coupling as claimed in claim 15, wherein the ports on each component share the same geometry.

18. The transfer coupling as claimed in claim 17, wherein the shared geometry is axially extending slots.

19. The transfer coupling as claimed in claim 17, wherein the shared geometry is round holes.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Embodiments of the invention will now be described by way of example with reference to the accompanying Figures in which:

(2) FIG. 1 is a sectional side view of a gas turbine engine having a geared fan;

(3) FIG. 2 is an enlargement of a planetary arrangement epicyclic gearbox used in the gas turbine engine of FIG. 1 and coupled to a static housing by means of a transfer coupling in accordance with the present invention;

(4) FIG. 3 is a section through a coupling in accordance with the present invention;

(5) FIG. 4 is a section through a component of another embodiment of a coupling in accordance with the present invention.

DETAILED DESCRIPTION OF DRAWINGS AND EMBODIMENTS

(6) Referring to FIG. 1, a two-shaft gas turbine engine 10 has a principal rotational axis 9. The engine 10 comprises an air intake 12 and a propulsive fan 23 that generates two airflows A and B. The gas turbine engine 10 comprises a core engine 11 having, in axial flow A, a low pressure booster compressor 14, a high-pressure compressor 15, combustion equipment 16, a high-pressure turbine 17, a low pressure turbine 19 and a core exhaust nozzle 20. A nacelle 21 surrounds the gas turbine engine 10 and defines, in axial flow B, a bypass duct 22 and a bypass exhaust nozzle 18. The fan 23 is attached to and driven by the low pressure turbine 19 via shaft 26 and epicyclic gearbox 30.

(7) The gas turbine engine 10 works in a conventional manner so that air in the core airflow A is accelerated and compressed by the high pressure booster compressor 14 and directed into the high pressure compressor 15 where further compression takes place. The compressed air exhausted from the high pressure compressor 15 is directed into the combustion equipment 16 where it is mixed with fuel and the mixture combusted. The resultant hot combustion products then expand through, and thereby drive the high pressure and low pressure turbines 17, 19 before being exhausted through the nozzle 20 to provide some propulsive thrust. The high pressure turbine 17 drives the high pressure compressor 15 by a suitable interconnecting shaft. The fan 23 normally provides the majority of the propulsive thrust.

(8) A known mechanical arrangement for a two-shaft geared fan gas turbine engine 10 is shown in FIG. 1. The low pressure turbine 19 drives the shaft 26, which is coupled to a sun wheel, or sun gear, 28 of the epicyclic gear arrangement 30. Radially outwardly of the sun gear 28 and intermeshing therewith, in conventional manner, is a plurality of planet gears 32 that are coupled together by a planet carrier 34. The planet carrier 34 constrains the planet gears 32 to precess around the sun gear 28 in synchronicity whilst enabling each planet gear 32 to rotate about its own axis independently. The planet carrier 34 is coupled via linkages 36 to the fan 23 in order to drive its rotation about the engine axis 9. Radially outwardly of the planet gears 32 and intermeshing therewith is an annulus or ring gear 38 that is coupled to stationary structure 24. As can be seen, the transfer coupling of the invention 40 sits on the shaft 26. The rotatable component 41 (see FIG. 3) rotates with shaft 26, the static component 42 of the coupling is mounted to a stationary structure 24 in a fixed position radially outboard of the rotatable component 41.

(9) FIG. 3 shows a section through a transfer coupling 40 in accordance with the invention. In particular, the figure shows the arrangement of ports 41a, 42a in each of the components. The coupling comprises an outer ring 42 which, in use, is secured in a fixed rotational position to a stationary structure (for example structure 24 of FIG. 2). Radially inwardly and in close radial contact with the stationary component 42 is a rotatable component 41 which, in use, is secured to a rotating structure (such as sun gear 28) such that the rotatable component rotates relative to the stationary component 42, with the rotating structure.

(10) As can be seen, the ports 41a, 42a in each of the components of the coupling are substantially equally spaced about the annulus. The outer, stationary component 42 has twenty-eight substantially identical ports 42a. The circumferential dimensions of the ports along the circumference of the coupling are very similar to that of the gaps between them creating a circumferential packing factor of about 50%.

(11) The inner, rotatable component 41 has twenty-nine substantially identical ports 41a. Again, the dimensions of the ports along the circumference of the coupling are very similar to that of the gaps between them creating a circumferential packing factor of about 50%.

(12) In use, the inner rotatable component 41 rotates relative to the stationary component 42 in the direction shown by the arrow (though this is not essential). As can be seen, at the illustrated rotational position, there is a significant majority of ports 41a of the rotatable component in fluid communication with ports 41b. Since the arrangement of the ports on each component is rotationally symmetrical, this will be the state of the coupling at any rotational position of the rotatable component, only angularly shifted.

(13) FIG. 4 shows a component of a coupling in accordance with the invention. The arrangement of ports 40a shown may be applied to either or both of the structural and rotatable components of a coupling of the invention.

(14) The skilled person will appreciate that except where mutually exclusive, a feature described in relation to any one of the above aspects may be applied mutatis mutandis to any other aspect. Furthermore except where mutually exclusive any feature described herein may be applied to any aspect and/or combined with any other feature described herein.

(15) It will be understood that the invention is not limited to the embodiments above-described and various modifications and improvements can be made without departing from the concepts described herein. Except where mutually exclusive, any of the features may be employed separately or in combination with any other features and the disclosure extends to and includes all combinations and sub-combinations of one or more features described herein.