GB2530735A

GB2530735A - Mounting arrangement

Info

Publication number: GB2530735A
Application number: GB1417206.8A
Authority: GB
Inventors: Glyn David Brain
Original assignee: Rolls Royce PLC
Current assignee: Rolls Royce PLC
Priority date: 2014-09-30
Filing date: 2014-09-30
Publication date: 2016-04-06
Also published as: GB201417206D0

Abstract

A retaining arrangement 450 that retains the head of a bolt in the event that it shears from the rest of the bolt comprises a retention bracket 410 that has at least two connected integral washers 412, each washer 412 being for receiving a fastener such as a nut or bolt 430. The arrangement 450 also comprises at least two retention plates 420 which are arranged to fit around a head of a fastener. The retention bracket 410 includes a connection portion 414 to connect the washers 412 together.

Description

MOUNTING ARRANGEMENT

All modern aircraft are provided with power systems that need to be connected to an airframe. The connection between the power system and the airframe needs to be such that the power system can be carried by the airframe, and the thrust generated by the power system can be transferred to the airframe.

The thrust generated by modern gas turbine engines, such as turbofan engines, can be extremely high, for example up to and even in excess of 100000 lbs. Accordingly, the mounting arrangements that are required to attach the gas turbine engines to the airframes are necessarily strong enough to transfer such high loads, meaning that they contribute significantly to the weight of the gas turbine engine installation, and thus to the overall weight of the aircraft.

Furthermore, it is essential that the mounting arrangements operate reliably, and that continued safe operation in the event that a part of the mounting arrangement fails or breaks. For example, where fasteners such as bolts are used in the mounting arrangement, at least one of the fasteners may be redundant, such that if one fastener breaks (for example due to a bolt head sheering off), then the remaining fasteners are sufficient to allow the system to continue to function as normal. However, in some regions of an engine or aircraft installation, the broken parts of a fastener may cause significant damage if released.

It is desirable to be able to prevent parts of a broken fastener from causing damage.

According to an aspect, there is provided a retaining arrangement for retaining the head of a fastener in the event that the head separates from the rest of the fastener. The retention bracket comprises at least two integrated washers. Each washer is shaped to fit underneath the head of a respective fastener. The retaining arrangement comprises at least two retention plates. Each retention plate corresponds to one of the integrated washers and/or one of the fasteners. Each retention plate is constructed and/or arranged (for example shaped) to fit around at least a part of the respective fastener head (for example around more than 180 degrees of the perimeter of the fastener head). The retention bracket comprises a connecting portion that extends between the integrated washers so as to connect the washers together.

According to an aspect, there is provided a method of securing a first element to a second element. The method comprises inserting at least two fasteners through respective integrated washers of a retention bracket, each fastener comprising a fastener head. The method comprises inserting each fastener into respective holes in the first and second elements. The method comprises fitting a retention plate around at least a part of each fastener head. Following insertion of a fastener into the first and second elements, the fastener head is on the opposite side of its respective integrated washer to the first and second elements. The retention bracket comprises a connecting portion that extends between the integrated washers so as to connect the washers together.

The first element may be part of, or directly connected to, a gas turbine engine. The second element may be part of, or directly connected to, an aircraft structure.

According to an aspect, there is provided a method of retaining a head of a fastener in position in the event that the head becomes detached from the rest of the fastener (for example due to the head sheering off the bolt). The method comprises providing a retention bracket comprising at least two integrated washers, each washer being constructed and/or arranged to fit underneath the head of a respective fastener head. The method comprises inserting at least two of the fasteners through respective integrated washers. The method comprises inserting each fastener into a respective hole of a component to be fastened such that one of the integrated washers is provided between each the component and each fastener head. The method comprises fitting a retention plate around at least a part of each fastener head. The retention bracket comprises a connecting portion that extends between the integrated washers so as to connect the washers together.

The methods and arrangements disclosed herein ensure that if the head of a fastener (such as a bolt) becomes detached from the rest of the fastener, then the bolt is retained in position, thereby preventing it from causing damage to surrounding structures or components. For example, the head of the fastener may be retained by the retention plate and the respective integrated washer of the retention bracket.

Each retention plate may be shaped to correspond to and engage with at least a portion of the perimeter of its respective fastener head. This may prevent rotation of the fastener.

Each retention plate may comprise an opening into which the respective fastener head can be inserted (for example during assembly), the opening thereby being arranged to surround the perimeter of the fastener head (for example during use). The opening may be a through hole. The opening may be the same shape as the fastener head, for example a hexagonal shape or a star shape.

Each retention plate may be attached to the retention bracket. For example, each retention plate may be connected to and/or removably attached to the retention bracket using a connecting element, which may be a threaded connecting element, such as a screw.

Each retention plate may comprise a slotted hole for fixing the retention plate in position.

The slotted hole may allow the orientation of a retention plate relative to its respective fastener head to be adjusted. This may allow, for example, the orientation of an opening in the retention plate to be adjusted so as to correspond to the orientation of the fastener head.

The retention plates may be removable from the rest of the retaining arrangement, although this need not be the case.

Each integrated washer may comprise a seat portion. The seat portion may be arranged (for example shaped and/or sized) to receive the underside of its respective fastener head.

According to an aspect, there is provided a fixing arrangement for fixing a first element to a second element. The fixing arrangement comprises a retaining arrangement as described and/or claimed herein. The fixing arrangement comprises at least two fasteners comprising fastener heads. Each fastener is inserted through a respective one of the integrated washers. The head of each fastener is supported on the respective washer. A respective one of the retention plates extends around at least a part of each fastener head.

Any of the fasteners described and/or claimed herein may take any suitable form. For example, a fastener may be a threaded fastener having a threaded portion with a small cross-section that a head, such as a bolt having a bolt head.

Any of the fasteners described and/or claimed herein may comprise a nut. First and second elements may be clamped between a bolt head and a nut.

The methods and arrangements described and/or claimed herein may be applied to any suitable application, for example applications in which multiple fasteners are used, and in which the ability to avoid parts of a fastener becoming detached in the event of failure is desirable.

For example, according to an aspect, there is provided a gas turbine engine installation comprising: a gas turbine engine; and an aircraft structure. The gas turbine engine and the aircraft structure are connected together using a mounting arrangement that comprises a fixing arrangement as described and/or claimed herein. The fixing arrangement may be provided, for example, in the part of the mounting arrangement that is attached to an aircraft pylon.

Any feature described and/or claimed herein may optionally be used in combination with any other compatible feature described and/or claimed herein.

Embodiments of the disclosure will now be described by way of non-limitative example with reference to the accompanying drawings in which: Figure 1 shows a cross-section through a gas turbine engine; Figure 2 shows a part of a gas turbine engine mounted to a pylon of an aircraft; and Figure 3 shows a fixing arrangement that includes a retaining arrangement.

With reference to Figure 1, a ducted fan gas turbine engine generally indicated at 10 has a principal and rotational axis X-X. The engine 10 comprises, in axial flow series, an air intake 11, a propulsive fan 12, an intermediate pressure compressor 13, a high-pressure compressor 14, combustion equipment 15, a high-pressure turbine 16, and intermediate pressure turbine 17, a low-pressure turbine 18 and a core engine exhaust nozzle 19. The engine also has a bypass duct 22 and a bypass exhaust nozzle 23.

The gas turbine engine 10 works in a conventional manner so that air entering the intake 11 is accelerated by the fan 12 to produce two air flows: a first air flow A into the intermediate pressure compressor 13 and a second air flow B which passes through the bypass duct 22 to provide propulsive thrust. The intermediate pressure compressor 13 compresses the air flow A directed into it before delivering that air to the high pressure compressor 14 where further compression takes place.

The compressed air exhausted from the high-pressure compressor 14 is directed into the combustion equipment 15 where it is mixed with fuel and the mixture combusted. The resultant hot combustion products then expand through, and thereby drive the high, intermediate and low-pressure turbines 16, 17, 18 before being exhausted through the nozzle 19 to provide additional propulsive thrust. The high, intermediate and low-pressure turbines 16, 17, 18 respectively drive the high and intermediate pressure compressors 14, 13 and the fan 12 by suitable interconnecting shafts.

Each of the high, intermediate and low-pressure turbines 16, 17, 18 and the intermediate and high-pressure compressors 13, 14 comprises at least one stage comprising a set of rotor blades and a set of stator vanes. In use, the rotor blades rotate around the engine axis X-X, whilst the stator vanes are stationary within the engine.

It will be appreciated that the gas turbine engine 10 if Figure us shown by way of example only, and the present disclosure may be applied to any other type of gas turbine engine, for example with any arrangement of turbines, compressors, shafts and casings.

Figure 1 also shows a pylon 300 to which the gas turbine engine 10 is mounted via a front mounting arrangement 500, and a rear mounting arrangement 100 to form a gas turbine engine installation. The gas turbine engine installation also comprises a thrust strut 200, through which the motive force generated by the engine is transmitted to the pylon 300. The pylon 300 may be a part of an aircraft (for example attached to the wing of an aircraft), and thus the gas turbine engine installation may be part of an aircraft.

Figure 2 shows a perspective view of the schematic cross-section shown in Figure 1, with only a part of the engine 10 being shown in Figure 2. In this exemplary arrangement, the front and rear mounting arrangements 100, 500 are connected to casings of the gas turbine engine 10. In particular, the front mounting 500 is connected to a fan casing 50, and the rear mounting 100 is connected to a core casing 40. The thrust strut 200 is connected between the core casing 40 and the rear mounting 100, although it will be appreciated that other arrangements are also possible.

The mounting arrangements 100, 500 of Figures 1 and 2 comprise a fixing arrangement 400 for connection to the pylon 300. The fixing arrangement 400 comprises a retaining arrangement 450, as discussed in greater detail below in relation to Figure 3. A fixing arrangement 400 may be provided to one or both of the front and rear mounting arrangements 100, 500.

The retaining arrangement 450 comprises a retention bracket 410. The retaining arrangement 450 also comprises retention plates 420. The retaining arrangement 450 is constructed to retain the head 435 of a bolt 430 of the fixing arrangement 400 in the event that it becomes detached from the bolt, for example by shearing from the shaft of the bolt.

The retention bracket 410 comprises integrated washers 412. The integrated washers 412 are connected together via a connecting portion 414. The connecting portion 414 and the washers 412 may be formed initially as a single part or may be initially constructed as separate components and then joined and/or fixed together.

Each integrated washer 412 may take any suitable form. For example, each washer 412 may comprise a seat portion 413, as shown by way of example in Figure 3. The seat portion may be arranged (for example sized and/or shaped) to receive (for example engage and/or be engaged by) the underside of the bolt head 435. For example, the seat portion 413 may have a chamfer/radius that engages a corresponding chamfer/radius on the underside of the bolt head 435. A seat portion 413 may, for example, initially be formed as a separate component to the rest of the retention bracket 410. In one alternative, a seat portion 413 may be machined from the rest of the retention bracket 410. Of course, some arrangements may not comprise a separate seat portion 413, and the bolt heads 435 may be mounted directly onto the integrated washer 412.

Each retention plate 420 comprises a hole 422. The hole 422 is arranged (for example shaped and/or sized) to fit around the head 435 of a respective bolt when the retaining arrangement 450 is used in a fixing arrangement 400, as shown in Figure 3.

If the bolt head 435 were to become detached from the rest of the bolt 430, then it would be retained in position by a combination of the retention plate 420 and the retention bracket 410. In the Figure 3 example, in such an event, the retention bracket 410 would be retained in its original position by the remaining, undamaged, bolts 430. This would allow the detached bolt head 435 to be retained in position between its respective integral washer 412 and its respective retention plate 420.

In the example shown in Figure 3, the retention plate 420 is connected to the retention bracket 410, in particular in this exemplary arrangement to the connecting portion 414 of the retention bracket. The retention plate 420 may alternatively be connected to other features (not shown). The retention plates 420 in Figure 3 are connected to the retention bracket 410 using a threaded fixing 440, but it will be appreciated that any suitable arrangement may be used to attach the retention plate 420 in position In order to assemble the fixing arrangement 400, each fastener 430 is inserted through its respective integral washers 412. The fastener 430 then passes into one or more further holes of the component(s) that are being fastened, such as the pylon 300 and/or the mounting arrangement 100, 500 shown in Figures 1 and 2 for example. A nut may or may not be provided to an end of the fastener 430. Once the fastener 430 is in position, resting on an integral washer 412 of the retention bracket 41 0, the retention plate 410 may be attached. For example, the retention plate 410 may be slid over the head 435 of the bolt, and then fixed in position using a threaded fixing 440.

The retention plate 420 may also act as an anti-rotation plate. For example, a hole 422 in the retention plate 420 such as that shown in Figure 3 may correspond (for example in shape and size) to the perimeter of the head 435 of the bolt 430. Accordingly, when the retention plate 420 is fixed in position, it may not be possible to rotate (and thus tighten or untighten) the bolt 430.

The retention plate 420 may be provided with a slotted hole 424, as in the Figure 3 example.

The slotted hole 424 may enable the angle of the retention plate 420 to be adjusted, for example to correspond to the angular position of the bolt head 435.

It will be appreciated that whilst the retention plates 420 of Figure 3 are illustrated as having holes 422 the surround the bolt heads 435, other arrangements are possible. For example, rather than a hole 422, the retention plate 420 may be provided with one or more slots or recesses that correspond to a part of the shape of the bolt head 435.

Whilstthe integral washers 412 are shown as fitting around all of the shankof the bolt, this need not be the case, and at least one of the integral washers may only extend around a part of the shank of the bolt, for example in a "C" shape.

The bolt heads 435 are shown as have star shapes, but any other bespoke or conventional driving head shape may be used.

The exemplary arrangement of Figure 3 has three sets of fasteners 430, integral washers 412 and retention plates 420. However, other fixing arrangements 400 or retaining arrangements 450 may have any two or more sets of fasteners 430, integral washers 412 and retention plates 420, for example two, three, four, five, six, seven or more than seven.

The fixing arrangement 400 and retaining arrangement 450 have been described in relation to mounting a gas turbine engine lOto an aircraft pylon 300. However, it will be appreciated that a fixing arrangement 400 and/or a retaining arrangement 450 as described and/or claimed herein may be used for any suitable application, either within or outside the aerospace sector.

Where reference is made herein to a gas turbine engine, it will be appreciated that this term may include may be any type of gas turbine engine, including, but not limited to, a turbofan (bypass) gas turbine engine, turbojet, turboprop, ramjet, scramjet or open rotor gas turbine engine, and for any application, for example aircraft, industrial, and marine application.

Furthermore, it will be appreciated that many different arrangements in addition to those described herein may fall within the scope of the attached claims.

Claims

CLAIMSA retaining arrangement (450) for retaining the head (435) of a fastener (430) in the event that the head separates from the rest of the fastener comprising: a retention bracket (410) comprising at least two integrated washers (412), each washer being arranged to fit underneath the head of a respective fastener; and at least two retention plates (420), each retention plate corresponding to one of the integrated washers and being constructed and/or arranged to fit around at least a part of the respective fastener head, wherein the retention bracket comprises a connecting portion (414) that extends between the integrated washers so as to connect the washers together.
2. A retaining arrangement according to claim 1, wherein each retention plate has a portion (422) that is shaped to correspond to and engage with at least a portion of the perimeter of its respective fastener head so as to prevent rotation of the fastener.
3. A retaining arrangement according to claim 1 or claim 2, wherein each retention plate comprises an opening (422) into which the respective fastener head can be inserted, the opening thereby being arranged to surround the perimeter of the fastener head.
4. A retaining arrangement according to any one of the preceding claims, wherein each retention plate is attached to the retention bracket.
5. A retaining arrangement according to any one of the preceding claims, wherein each retention plate comprises a slotted hole (424) for fixing the retention plate in position, the slotted hole allowing the orientation of a retention plate relative to its respective fastener head to be adjusted.
6. A retaining arrangement according to any one of the preceding claims, wherein the retention plates are removable from the rest of the retaining arrangement.
7. A retaining arrangement according to any one of the preceding claims, wherein each integrated washer comprises a seat portion (413) that is arranged to receive the underside of its respective fastener head.
8. A fixing arrangement (400) for fixing a first element (300) to a second element (100), comprising: a retaining arrangement (450) according to any one of the preceding claims; and at least two fasteners (430) comprising fastener heads (435), wherein: each fastener is inserted through a respective one of the integrated washers such that its head is supported on the respective washer; and a respective one of the retention plates extends around at least a part of each fastener head.
9. A fixing arrangement according to claim 8, wherein each fastener comprises a bolt having a bolt head.
10. A fixing arrangement according to claim 9, wherein each fastener comprises a nut, such that the first and second elements can be clamped between the bolt head and the nut.
11. A gas turbine engine installation comprising: a gas turbine engine (10); and an aircraft structure (300), wherein the gas turbine engine and the aircraft structure are connected together using a mounting arrangement that comprises a fixing arrangement according to any one of claims 8 to 10.
12. A method of securing a first element (1 00) to a second element (300) comprising: inserting at least two fasteners (430) through respective integral washers (412) of a retention bracket (410), each fastener comprising a fastener head (435); inserting each fastener into respective holes in the first and second elements; and fitting a retention plate (420) around at least a part of each fastener head, wherein: following insertion of a fastener into the first and second elements, the fastener head is on the opposite side of its respective integrated washer to the first and second elements; and the retention bracket comprises a connecting portion (414) that extends between the integral washers so as to connect the washers together.
13. A method of securing a first element to a second element according to claim 12, wherein: the first element is part of, or is directly connected to, a gas turbine engine; and the second element is part of, or is directly connected to, an aircraft structure.
14. A method of retaining a head (435) of a fastener (430) in position in the event that the head becomes detached from the rest of the fastener comprising: providing a retention bracket (410) comprising at least two integrated washers (412), each washer being shaped to fit underneath the head of a respective fastener head; inserting at least two of the fasteners through respective integrated washers; inserting each fastener into a respective hole of a component (100, 300) to be fastened such that one of the integrated washers is provided between the component and each fastener head; and fitting a retention plate (420) around at least a part of each fastener head, wherein the retention bracket comprises a connecting portion (414) that extends between the integrated washers so as to connect the washers together.