Mount assembly

Abstract

A mount assembly for attaching a heat exchanger to a casing of a gas turbine engine comprises a first attachment feature by which in use the mount assembly is attached to the casing and a second attachment feature spaced from the first attachment feature by which in use the mount assembly is attached to the heat exchanger. The first and second attachment features are joined by an elongate member. The assembly is characterised in that the elongate member is significantly larger in a length direction and a height direction than in a thickness direction, so that it is relatively stiff in the length and height directions L, H and relatively flexible in the thickness direction T; the flexibility allowing movement in use within the mount assembly to accommodate differential thermal expansion between the heat exchanger and the casing.

Claims

1. A mount assembly for attaching a heat exchanger to a casing of a gas turbine engine, the assembly comprising: a first attachment feature by which the mount assembly is attached to the casing; a second attachment feature spaced from the first attachment feature by which the mount assembly is attached to the heat exchanger; and an elongate member that joins the first and second attachment features, wherein the elongate member is larger in a length direction, L, extending between the first and second attachment features and in a height direction, H, extending between the heat exchanger and the casing, than in a thickness direction, T, extending perpendicular to the length direction, L, and the height direction, H, so that the elongate member is more stiff in the length and height directions L, H, than in the thickness direction, and more flexible in the thickness direction T than in the length, L, and height, H, directions, the flexibility allowing movement within the mount assembly to accommodate differential thermal expansion between the heat exchanger and the casing.

2. The mount assembly of claim 1, in which the assembly comprises two first attachment features and two elongate members, each first attachment feature being joined to the second attachment member by a respective elongate member.

3. The mount assembly of claim 1, in which the elongate member is S-shaped.

4. The mount assembly of claim 1, in which the second attachment feature comprises a threaded insert.

5. An arrangement for mounting a heat exchanger on a casing of a gas turbine engine, the arrangement comprising a plurality of mount assemblies as claimed in claim 1.

Description

DESCRIPTION OF THE DRAWINGS

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

(2) FIG. 1 is a sectional side view of a gas turbine engine, as already described;

(3) FIG. 2A is a schematic cross-sectional view of a known type of mount assembly for an SAOHE, as already described, and FIG. 2B shows in more detail the circled region in FIG. 2A.

(4) FIG. 3 is a schematic perspective view of another known type of mount assembly, as already described;

(5) FIG. 4 is a schematic perspective view of a mount assembly;

(6) FIG. 5 shows the installation of the mount assembly of FIG. 5; and

(7) FIG. 6 is a schematic perspective view of a further mount assembly.

DETAILED DESCRIPTION

(8) In FIG. 4, a mount assembly is shown generally at 232. The mount assembly 232 comprises two first attachment features in the form of end bosses 234 and a second attachment feature in the form of a central boss 236. Each end boss 234 is joined to the central boss 236 by a respective elongate member in the form of a flexible beam 238. As can be seen from FIG. 4, the two flexible beams 238 are significantly larger in a length direction L and a height direction H than in a thickness direction T, as shown by the appended arrows, and therefore they will be relatively stiff in the length and height directions L, H and relatively flexible in the thickness direction T.

(9) A threaded insert 240 is located in the central boss 236, which in use receives a bolt 242 as will be explained below. In use bolts 244 pass through the end bosses 234 as will also be explained below.

(10) FIG. 5 shows the mount assembly 232 of FIG. 4 interposed between a fan casing 250 and a SAOHE 252. Two bolts 244 extend through the end bosses (234 in FIG. 4) to secure the mount assembly 232 to the fan casing 250 by means of nuts 254. Bolt 242 extends through the SAOHE 252 and is received by the threaded insert 240 to secure the SAOHE 252 to the mount assembly 232. A plurality of mount assemblies 232 spaced over the whole area of the SAOHE 252 secure the SAOHE 252 to the fan casing 250.

(11) The SAOHE 252 is therefore secured to the casing 250 via the plurality of mount assemblies 232. Because of the geometry of the mount assembly 232, specifically the geometry of the two flexible beams 238, the connection between the SAOHE 252 and the casing 250 is relatively rigid in a length direction of the bolts 242, 244 and in the direction of a line joining the two end bosses 234 (respectively directions H and L in FIG. 4); but relatively flexible in the direction perpendicular to those two directions (direction T in FIG. 4). This flexibility allows movement in the direction T within the mount assembly 232 to accommodate differential thermal expansion, without compromising the secure fixing of the SAOHE to the engine casing.

(12) FIG. 6 shows a further mount assembly 332. The mount assembly 332 comprises two first attachment features in the form of end bosses 334 and a second attachment feature in the form of a central boss 336. Each end boss 334 is joined to the central boss 336 by a respective elongate member in the form of a flexible beam 338. As in the arrangement of FIG. 4, a threaded insert 340 is located in the central boss 236, which in use receives a bolt 342. Similarly, in use, bolts 344 pass through the end bosses 334.

(13) In contrast to the arrangement in FIG. 4, the two flexible beams 338 are S-shaped. As in FIG. 4, however, the two flexible beams 338 are significantly larger in a length direction L and a height direction H than in a thickness direction T, as shown by the appended arrows; therefore they will also be relatively stiff in the length and height directions L, H and relatively flexible in the thickness direction T.

(14) The mount assembly 332 may be used to secure a SAOHE to an engine casing in the same way as shown in FIG. 5 for the mount assembly 232. As in that arrangement, the geometry of the mount assembly 332 will allow movement in the direction T within the mount assembly 332 to accommodate differential thermal expansion, without compromising the secure fixing of the SAOHE to the engine casing.

(15) Mount assemblies as shown in FIGS. 4 and 6 therefore provide a simpler and more reliable means for mounting SAOHEs or other heat exchangers to engine casings to accommodate differential thermal expansion. Because the flexibility in the mount assembly arises from the geometry of the assembly itself, it is not dependent on material or tolerance variability as in prior solutions; nor is It susceptible to variation over the life of the components.

(16) The mount assembly as shown in FIGS. 4 and 6 is easily manufactured using known techniques such as injection moulding or additive manufacturing. The material and the precise geometry of the mount assemblyfor example, the length and curvature of the flexible beams in the assembly of FIG. 4 or the length and configuration of the S-shape in the assembly of FIG. 6can be selected to provide the desired degree of flexibility (and, equally, the desired degree of rigidity in the other two, perpendicular, directions).

(17) 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.