GB2085117A

GB2085117A - Seals

Info

Publication number: GB2085117A
Application number: GB8032130A
Authority: GB
Original assignee: Rolls Royce PLC
Current assignee: Rolls Royce PLC
Priority date: 1980-10-06
Filing date: 1980-10-06
Publication date: 1982-04-21

Abstract

A seal (22) for use on a burner arm (18) of a gas turbine engine, to seal an opening (20) in a casing (14) comprises two piston ring seals (28) mounted in a two part casing (24,26), the casing being located in a slot (40) on the burner arm (18). The seal allows the use of relatively lightly sprung sealing elements whilst allowing a considerable degree of relative movement between the arm (18) and the casing (14) and still sealing the opening (20) to prevent loss of pressure from the casing (14). <IMAGE>

Description

SPECIFICATION A seal for use between relatively movable components This invention relates to a seal for use between relatively movable components, particularly components of gas turbine engines. During the operation of such engines relative movement takes place between many of the engine components due to the differential thermal expansions and contractions which occur. Where one component such as a fuel burner arm passes through another component such as a pressure casing, the opening in the casing must remain sealed at all times to prevent pressure losses.

A common method of sealing openings in these circumstances is to provide a pair of piston rings located in an annular slot on the burner, the piston rings only requiring a light compression to allow the burner to be positioned in the opening with the piston rings abutting the wall defining the casing opening and remaining located in the annular slot.

If the movement between the burner arm and the casing became relatively large, the piston rings may not be able to accommodate such a large movement without allowing a gap to appear between the rings and the burner arm, thereby allowing a loss of pressure from the casing. Piston rings of a greater radial width could be used but these would require quite large compressive forces to allow the burner arm to be sealingly located in the casing opening.

The present invention accordingly provides a seal for use between two relatively movable components, the seal comprising a housing formed in two parts, the two parts defining an annular recess, and at least two split sealing rings located in said recess, the housing being arranged to be secured to one of said components.

In one arrangement, one of the components comprises a fuel burner arm of a gas turbine engine and the other component comprises a pressure casing of a gas turbine engine, the burner arm passing through an opening in the casing, and the seal providing a seal between the burner arm and the casing.

The seal housing is preferably located in an annular slot on the burner arm, the said annular slot being formed by a shoulder on the burner arm and retaining ring which is secured to the burner arm after the seal housing containing the sealing rings has been assembled on the burner arm.

The present invention will now be more particularly described with reference to the accompanying drawings in which: Figure 1 is a seal according to the present invention located on a burner in an opening of a "gas turbine engine casing and Figure 2 shows the seal in Figure 1 to a larger scale.

Referring to the Figures a gas turbine engine, not shown in entirety, includes an annular combustion chamber 10 which receives a flow of compressed air from a compressor (not shown) through a ring of guide vanes 12, the chamber 10 being located in an annular housing 14 which is itself mounted inside the main engine casing 16.

The combustion chambers are fuelled by fuel burners 1 8 which are secured to the casing 1 6 and the arms 18 of which pass through openings 20 in the casing 14.

During operation of the engine relative movement takes place between the burner arm 1 8 and the casing 14 requiring a clearance between the arm and the casing. This clearance has to be sealed to prevent leakage of high pressure air from the casing 14 and a seal 22 is provided for this purpose.

The seal 22 comprises a split housing comprising upper and lower circular parts 24 and 26 and two piston ring seals 28 which are located in an annular slot 30 formed by the combination of the parts 24, 26. The seals 28 each have a slot (not shown) so that they are not continuous rings, thereby allowing the rings to be compressed to fit into the opening 20. The two ring seals 28 are aligned with each other so that the slots do not overlap, thereby providing between them a continuous seal.

The seal 22 is assembled on the burner arm by firstly placing the two ring seals between the two parts 24, 26 which form the split housing, placing the housing on the burner arm so that it abuts a shoulder 30 on the arm, placing a locating ring 32 against another shoulder 34 on the arm and securing the locating ring in position by any suitable means, e.g. welding.

The opening 20 in the casing 14 is defined by a collar 36 which has a convergent entrance so that when the burner arm on which the housing containing the ring seals 28 is now mounted is offered up to the opening, the ring seals will engage the convergent entrance and will be compressed as the burner arm is urged into position, so that when the burner arm is in position the ring seals 28 will be urged outwardly into contact with the parallel walled part of the collar 36.

The shoulder 30 together with the locating ring 32 and a flange 38 on the arm define an annular slot 40 in which the split housing is located. When relative movement takes place between the casing 14 and the burner arm 18, the housing and the seals 28 will remain in a sealing position whilst the arm can move with respect to the housing because of the clearance provided in the annular slot 40. The split housing is contained at all times in the annular slot so that there can be no leakage between the housing and the burner arm via the slot 40.

It will be noted that the invention provides a seal between relatively movable components in which the sealing elements need only be relatively lightly sprung but which also allows a considerable degree of relative movement because the sealing elements are mounted in a housing which is itself movable on one of the components.

The invention has been described in relation to a burner arm and casing of a gas turbine engine, but it can also be applied to other gas turbine components, or components in other engineering arrangments where a seal has to be provided which also allows for relative movement.

Claims

1. A seal for use between two relatively movable components, the seal comprising a housing formed in two parts, the two parts defining an annular recess, and at least two split sealing rings located in said recess, the housing being arranged to be secured to one of said components in a manner to allow relative movement between the housing and said one component.

2. A seal as claimed in claim 1 in which the housing is arranged to be mounted in an annular slot on said one component.

3. A seal as claimed in claim 1 or claim 2 in which said one component comprises a burner arm of a gas turbine engine and the other component comprises a casing of a gas turbine engine having an opening in which the burner arm is located.

4. A gas turbine engine having a casing with a plurality of openings in each of which a burner arm is located, each burner arm having mounted thereon a seal, the seal comprising housing formed in two parts, at least two sealing elements located in a recess formed by said two parts, the housing being sealingly mounted and movable in a recess on the burner arm and the said at least two sealing elements being in sealing engagement with a wall defining the opening in the casing.

5. A gas turbine engine as claimed in claim 4 in which the wall defining the opening has a convergent entrance portion.

6. A seal constructed and arranged for use and operation substantially as herein described with reference to and as shown in the accompanying drawings.

7. A gas turbine engine including a seal as claimed in claim 6.