GB2452232A

GB2452232A - Nut/bolt retainer

Info

Publication number: GB2452232A
Application number: GB0705331A
Authority: GB
Inventors: Steven Hillier
Original assignee: Rolls Royce PLC
Current assignee: Rolls Royce PLC
Priority date: 2007-03-21
Filing date: 2007-03-21
Publication date: 2009-03-04
Also published as: GB0705331D0

Abstract

A nut/bolt retainer (32) for preventing release of a nut/bolt comprises an attachment portion (34), for securing the retainer (32) to a fixed structure (26, 28), and an engagement portion for engaging the nut (30). The attachment portion (34) defines an arcuate slot (36).

Description

NUT RETAINER

The present invention relates to a retainer device for a nut or a bolt of such an assembly.

Nuts and bolts are commonly retained using a length of wire passed through two holes, one in the nut or bolt the other in a related plate or flange of a fixed location.

The wire is then either twisted or crimped to retain and ensure the nut/bolt does not rotate thus becoming loose or lost during service. Where no hole is available in a plate or flange, a tab washer may be used. This can be fastened under another bolt, with the tab and hole positioned to attach the wire thereto.

Whereas the use of wire for retaining nut and bolts is adequate, there is a danger of the ends of the wire fouling protective clothing of maintenance staff and of the wire fretting against the bolted component.

Therefore it is an object of the present invention to provide a more robust nut or bolt retainer having no sharp features.

In accordance with the present invention a [for me to fill in later) The present invention will be more fully described by way of example with reference to the accompanying drawings in which: Figure 1 is a schematic section of part of a ducted fan gas turbine engine; Figure 2 is a perspective front view of a nut retainer in situ and in accordance with the present invention; Figure 3 is a sectional view AA in Figure 4 of the nut retainer; Figure 4 is a plan view of the nut retainer; Figure 5 is a plan view of an alternative arrangement of the nut retainer; Figure 6 is a plan view of yet another alternative arrangement of the nut retainer.

Referring to Figure 1, a ducted fan gas turbine engine generally indicated at 10 has a principal and rotational axis 11. The engine 10 comprises, in axial flow series, an air intake 9, 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 exhaust nozzle 19.

A nacelle 21 generally surrounds the engine 10 and defines the intake 9, a bypass duct 22 and an exhaust nozzle 23. A casing 26 surrounds the core engine.

The gas turbine engine 10 works in the conventional manner so that air entering the intake 9 is accelerated by the fan 12 to produce two air flows: a first airflow A into the intermediate pressure compressor 13 and a second airflow B which passes through a bypass duct 22 to provide propulsive thrust. The intermediate pressure compressor 13 compresses the airflow 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.

The fan 12 is circumferentially surrounded by a structural member in the form of a fan casing 24, which is supported by an annular array of outlet guide vanes 25.

Referring to Figures 2, 3 and 4, pipe 27B is axially assembled into the casing 26 until visible through the hole formed in a boss 28, which is formed on the radially outer side of the casing 26. A sealing sleeve 41 locates by diameter and flange into boss 28 and fits over pipe 27B via a tongue and groove 43 arranged to prevent torque loads being transmitted through the pipe 27B during assembly. A bolt 62 secures the sleeve 41. A pipe 27A passes through the sleeve 41. The pipes 27A and 27B have complimentarily shaped ends to fit one another. Pipe part 27B is secured via a hollow bolt assembly 29, engaging one another via threaded ends. A nut or bolt retainer 32 fits around the hollow bolt assembly 29 and is itself retained under bolt 62, which may have a self locking thread for bolt retention.

In service, the casing 26 and/or pipe 27 can experience vibrations that are capable of causing the bolt assembly 29 to release. To prevent rotation of the nut 30 or bolt a retainer 32 is fitted around and engages the nut and is itself attached to the boss 28.

The nut/bolt retainer 32 comprises an attachment portion 34, for securing the retainer 32 to a fixed structure (casing 26 or boss 28) via a bolt, and an engagement portion 36 for engaging the nut 30.

The attachment portion 34 defines an arcuate slot 36, which is preferably part of a circumference of a circle defined by a radius R from the centre 46 of the nut/bolt 30.

The engagement portion 36 comprises two fingers 40, 42 which each engage either side of the nut/bolt 30. The engagement portion 36 defines a complimentarily shaped recess 44 to the nut/bolt 30. The recess 44 comprises serrations 48 that engage the sides 50 of the nut/bolt 30.

The recess 44 comprises two (or more) serrations 48 for every side 50 of the nut/bolt 30, such that the extent of the arcuate slot 36 is minimised. Note that the nut 30 may be fully tightened in any rotational position relative to the securing means 62. For example, in Figure 4, a hexagonal nut is being retained. The sides are angled 60 degrees from one another and thus if there were equal numbers of recess serrations 48 to nut sides 50, the angular extent a of the slot 36 would need to be 60 degrees. However, with twice the number of recess serrations 48 to nut sides 50, the angular extent a of the slot 36 would be reduced to 30 degrees.

The engagement portion 36 is raised from the fixed structure 26, 28 via first and second legs 52, 54. The second leg(s) 52, 54 comprise a foot 56. The retainer 32 is biased such that when secured to the fixed structure 26, 28 its opposite end 58 is forced against the fixed structure 26, 28.

It should be apparent to the skilled artisan that the engagement portion 32 may extend completely around the nut particularly where there is no pipe 27 or other obstruction.

In Figure 5, an alternative nut retainer 32 is shown having petals 64 which fold into the paper as shown by the arrows 66. Essentially the petals 64 are folded to be approximately perpendicular to the plane of the paper so that they provide further engagement with the nut or bolt 30. The petals 64 also support the fingers 42 away from the boss 28 or second securing component 41.

Figure 6 shows yet another alternative arrangement of the nut retainer 32 comprising a securing slot 36 at each end. This embodiment more robust and is particularly useful where higher forces are experienced.

Claims

Claims 1. A nut/bolt retainer (32) for preventing release of a nut/bolt (30), the retainer comprising an attachment portion (34), for securing the retainer (32) to a fixed structure (26, 28), and an engagement portion (36) for engaging the nut/bolt (30), characterised in that the attachment portion (34) defines an arcuate slot (36)
2. A nut/bolt retainer (32) as claimed in claim 1, wherein arcuate slot (36) is part of a circumference of a circle defined by a radius (R) from the centre of the nut/bolt (30)
3. A nut/bolt retainer (32) as claimed in any one of claims 1-2, wherein the engagement portion (36) comprises two fingers (40, 42) which each engage either side of the nut/bolt (30)
4. A nut/bolt retainer (32) as claimed in any one of claims 1-3, wherein the engagement portion (36) defines a complimentarily shaped recess (44) to the nut/bolt (30)
5. A nut/bolt retainer (32) as claimed in claim 4, wherein the recess (44) comprises serrations (48) to engage the sides (50) of the nut/bolt (30)
6. A nut/bolt retainer (32) as claimed in claim 5, wherein the recess (44) comprises two or more serrations (48) for every side (50) of the nut/bolt (30), such that the extent of the arcuate slot (36) is minimised.
7. A nut/bolt retainer (32) as claimed in any one of claims 1-6, wherein the engagement portion (36) is raised from the fixed structure (26, 28) via first and second legs (52, 54)
8. A nut/bolt retainer (32) as claimed in claim 7, wherein at least one of the second legs (52, 54) comprises a foot (56).
9. A nut/bolt retainer (32) as claimed in any one of claims 1-8, wherein the retainer (32) is biased such that when secured to the fixed structure (26, 28) its opposite end (58) is forced against the fixed structure (26, 28)
10. A nut/bolt retainer (32) as claimed in any one of claims 1--9, wherein the retainer (32) comprises petals (64) that provide further engagement with the nut or bolt (30) -
11. A nut/bolt retainer (32) substantially as described in this specification and with reference to and as shown in figures 2-4 of the accompanying drawings.