MOUNTING BRACKET

Abstract

A mounting bracket for mounting an accessory to a gas turbine engine comprises a space frame structure. The space frame structure comprises a plurality of struts joined to one another at nodes.

Claims

1. A mounting bracket for mounting an accessory to a gas turbine engine, the bracket comprising a space frame structure, the space frame structure comprising a plurality of struts joined to one another at nodes.

2. The mounting bracket of claim 1, in which the space frame structure comprises a double layer grid comprising a first layer and a second layer.

3. The mounting bracket of claim 2, in which at least one node is extended to form a pillar that acts as a node for both the first layer and the second layer.

4. The mounting bracket of claim 2, in which the first layer and the second layer converge towards a periphery of the bracket, so that at least one node at the periphery acts as a node for both the first layer and the second layer.

5. The mounting bracket of claim 2, in which at least one strut in the first layer is linked by a brace to a corresponding strut in the second layer.

6. The mounting bracket of claim 1, in which the space frame structure forms an L shape.

7. The mounting bracket of claim 1, in which at least one of the struts is curved.

8. The mounting bracket of claim 1, in which at least one node is configured to form an attachment boss.

9. The mounting bracket of claim 8, in which a first plurality of extended nodes forms a first set of attachment bosses for attaching an accessory to the bracket.

10. The mounting bracket of claim 8, in which a second plurality of extended nodes forms a second set of bosses for attaching the bracket to a casing or nacelle of a gas turbine engine.

11. The mounting bracket of claim 10, in which the first set of bosses lies substantially in a first plane and the second set of bosses lies substantially in a second plane, and the first and second planes are substantially parallel.

12. The mounting bracket of claim 10, in which the first set of bosses lies substantially in a first plane and the second set of bosses lies substantially in a second plane, and the first and second planes are substantially perpendicular.

Description

[0023] Embodiments will now be described, by way of example only, with reference to the Figures, in which:

[0024] FIG. 1 is a sectional side view of a gas turbine engine, as already described;

[0025] FIG. 2 is a perspective view of a first embodiment of a bracket;

[0026] FIG. 3 is a side view of the bracket of FIG. 2;

[0027] FIG. 4 is a perspective view of a second embodiment of a bracket;

[0028] FIG. 5 is a perspective view of a third embodiment of a bracket;

[0029] FIG. 6 is a perspective view of the bracket of FIG. 5 mounted to a casing of a gas turbine engine; and

[0030] FIG. 7 is a perspective view of the bracket of FIG. 6, with three engine accessories mounted on it.

[0031] FIG. 2 shows a bracket 30. The bracket comprises a space frame structure. The space frame structure comprises struts 32 (for example 32a, 32b, 32c, 32d) which are joined to other struts at nodes 34 (for example 34a, 34b).

[0032] The space frame structure comprises a double layer grid, so struts 32a, 32c and nodes 34a, 34c are part of a first layer and struts 32b, 32d and nodes 34b, 34d are part of a second layer. Struts 32a, 32b and 32c, 32d occupy corresponding positions in the first and second layers, as similarly do nodes 34a, 34b and 34c, 34d. This structure provides a bracket with a greater dimension in its through-thickness direction, which enhances its strength and stiffness compared with a single-layer bracket; but the space frame construction minimises the weight of the bracket.

[0033] FIG. 3 shows a side view of the bracket 30 of FIG. 2, in which the first layer 36 and the second layer 38 are more clearly visible. Node 40a, which is in the first layer, and node 40b, which is in the second layer, are extended so they join to form a pillar 42 which links the first and second layers. This linking of the layers of the space frame structure provides greater stiffness with a minimal weight penalty. The two layer construction increases the stiffness of the bracket by adding additional bracing below the mounting points. It also allows the tuning of the bracket so that the vibration performance may be matched to the engine environment at minimal weight penalty.

[0034] Towards the periphery of the bracket 30, the first layer 36 and the second layer 38 converge, as seen in the struts 44a, 44b. Consequently, at the periphery of the bracket the first layer and second layer are coincident, and the nodes 46, 48 at these positions act as nodes both for the first layer and for the second layer.

[0035] FIG. 4 shows a perspective view of a second embodiment of a bracket. Some features of FIG. 4 are identical to features of FIG. 2, and for these the same reference numbers have been used.

[0036] The bracket 30 comprises struts 32, which are joined at nodes 34. In this embodiment, struts 32a and 32b are linked by a brace 46 so that the combination of struts 32a, 32b and brace 46 forms an I-beam structure. The bracing of the struts provides a bracket with greater strength and stiffness, although there is of course an increase in weight. In other embodiments, the two struts may be linked by braces of other forms or constructions. However, the I-beam is particularly suitable as it has the stiffest cross-section in bending.

[0037] FIG. 5 shows a perspective view of a third embodiment of a bracket. As in the previous embodiments the bracket 130 comprises a space frame structure of struts joined at nodes. In contrast to the previous embodiments, the bracket 130 is not formed as a double layer grid, but has a generally L-shaped geometry. Also in contrast to the previous embodiments, some of the struts in bracket 130 are curved, for example struts 132. Curved struts allow additional stiffness while being very space-efficient, thereby minimising the footprint of the bracket. Also, curved struts allow more flexibility than straight struts under thermal expansion.

[0038] A first plurality of nodes 134a is configured to form attachment bosses by which an accessory may be attached to the bracket, by extending the radius and depth of each of the nodes. The attachment method will vary depending on a number of factors including available space and clearance; the attachment method may for example be by bolt and nut, or by bolt and threaded insert in the bracket.

[0039] Adjacent to the nodes 134a is a feature 136 comprising three linear stiffening features (visible as “stripes” in FIG. 5). The combination of the curved struts 132 with the stiffening features of 136 allows tooling access to the bolts attaching the accessory to the bracket via the nodes 134a. In the absence of this feature 136, the sail feature 138 would have to be recessed back, which would compromise the overall stiffness of the structure.

[0040] A second plurality of nodes 134b is similarly configured to form attachment bosses by which the bracket may be attached to a casing of a gas turbine engine. Some of the nodes 134b may be configured by being thicker than others, or by other features such as recesses or projections, depending on the particular mechanical and geometric requirements of the installation.

[0041] FIG. 6 shows the bracket 130 of FIG. 5 mounted on a casing 140 of a gas turbine engine. Bosses 142 attached to, or integrally formed with, the casing 140 extend radially outward from the casing so that the bracket 130 may engage with them and be secured to them. In this embodiment the bracket 130 is secured to the bosses 142 by bolts engaging with threads in the bosses. The bracket 130 is capable of carrying three engine accessories, on three sets of attachment bosses 144a (consisting of the nodes 134a described above), 144b and 144c. Each set of attachment bosses 144a, 144b, 144c consists of four bosses. In this embodiment, the positioning of the sets 144a, 144b, 144c of attachment bosses has been selected to minimise the footprint of the bracket on the casing while still permitting tool and hand access to the accessories.

[0042] FIG. 7 shows the bracket 130 of FIG. 6 mounted on a casing of a gas turbine engine, and with three sensors 146 mounted on it. In this embodiment the sensors 146 are pressure transducers. Each sensor is mounted to one of the sets 144a, 144b, 144c (previously described) of four attachment bosses.

[0043] It is envisaged that a bracket such as those described will advantageously be made using an additive manufacture technique, such as electron beam melting (EBM) or direct laser deposition (DLD). Such a manufacturing technique allows the construction of a bracket with optimised vibration and stress performance at minimal weight. Additive manufacturing techniques also allow the manufacture of complex shapes that may not be feasible with conventional machining techniques because of problems with tool access or because of the complexity or cost of the machining required.

[0044] The brackets may be made from any suitable material. It is envisaged that they would normally be made from a metallic material, for example nickel-based alloy or titanium, but other materials—metallic or non-metallic—may be used where suitable for the operating conditions.

[0045] It will be understood that the invention is not limited to the embodiments described above 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.