GB2107809A

GB2107809A - Fuel pipe seal

Info

Publication number: GB2107809A
Application number: GB08131357A
Authority: GB
Inventors: Norman Roberts
Original assignee: Rolls Royce PLC
Current assignee: Rolls Royce PLC
Priority date: 1981-10-16
Filing date: 1981-10-16
Publication date: 1983-05-05

Abstract

A fuel pipe (10) is provided with a modified end portion (11) which locates in a connector (20). The fuel pipe modified end portion (11) is provided with two portions (12, 14) which are of different diameters and have resilient annular sealing members (17, 19) located upon them. The sealing members (17, 19) radially space apart the fuel pipe modified end portion (11) and the connector so as to permit limited relative movement between them. A fuel drain (26) is provided in the connector (20) between the two sealing members (17, 19) so that any fuel leakage past the smallest seal (19) will not result in fuel leaking to the exterior of the fuel pipe/connector assembly. <IMAGE>

Description

SPECIFICATION Fuel pipe seal This invention relates to fuel pipe seals and in particular to fuel pipe seals which have improved resistance to uncontrolled and undetected leakage.

If a fuel system is required to carry fuel at high pressure, as is the case for instance in the fuel system of a gas turbine engine, great demands are placed upon the fuel pipes and seals present in the system. If the pipes or seals should fail and allow the uncontrolled leakage of fuel from the fuel system, then there is a risk that the fuel will ignite and cause a fire.

Various ways of preventing the ignition of leaking fuel have been suggested. One comprises placing all of the seals and pipes at risk within an area which is well ventilated. This, however, can result in a loss in efficiency of the device to which the fuel system belongs through overcooling.

Another method preventing ignition comprises providing shrouds around the relevant portions of the fuel system so that any fuel leakages are contained within the shrouding and are thereby prevented from igniting. Such shroudings can, however, be difficult to manufacture and install and may be prone to damage as a result of frettage between the shrouding and fuel pipes.

It is an object of the present invention to provide a fuel system which includes a fuel pipe seal having improved resistance to the cuncontrolled and undetected leakage of fuel therefrom into areas in which the fuel could ignite and which also minimises strains on the fuel pipes.

According to the present invention, a fuel system includes a fuel pipe, a connector for the reception of one end of said fuel pipe and sealing means interposed between said fuel pipe and said connector, said sealing means comprising at least two annular axially spaced apart resilient sealing members which radially space apart said fuel pipe and said connector so as to permit limited relative movement therebetween, said connector being provided with means for draining any fuel from the space between said sealing members.

Said at least two sealing members are preferably of different diameters, the sealing member of smallest diameter being closest to the end of said fuel pipe, said fuel pipe and connector being so configured as to accommodate said at least two sealing members.

Preferably two of said sealing members are provided between the end of said fuel pipe and the position of said fuel draining means.

The invention will now be described, by way of example, with reference to the accompanying drawing which is a sectional side view of a part of a fuel system in accordance with the present invention.

With reference to the drawing a pipe 10, which is adapted for the passage therethrough of high pressure fuel, has a modified end portion 11. The modified end portion 11 is a separate item which is fixidly attached to the fuel pipe 10 but it will be appreciated that it could in fact be an integral port of the fuel pipe 10.

The modified end portion 11 has three coaxial sections 12, 13 and 14 which all have different diameters. More particularly the section 14 having the smallest diameter is adjacent the end 1 5 of the pipe 10 and the remaining sections 13 and 12 are of progressively larger diameter. The largest diameter section 12 is provided with an annular groove 16 which accommodates a resilient sealing member 17. The smallest diameter portion 14 is provided with two axially spaced apart annular grooves 18 which respectively accommodate two further resilient sealing members 19.

The fuel pipe modified end portion 11 locates within a connector 20 which is provided with a duct 21 to either receive fuel from or direct fuel to the fuel pipe 10. The smallest diameter sections 14 of the fuel pipe modified end portion 11 locates within the duct 21. The remaining sections 13 and 12 are also located within the connector 20 which has appropriately dimensioned portions 22 and 23 to receive them. The duct 21 and the connector portions 22 and 23 are of greater diameter than the sections 14, 13 and 12 respectively of the modified fuel pipe end 11 so that the sealing members 17 and 19 radially space them apart. Consequently the sealing members 17 and 19 constitute the only means of support between fuel pipe 10 and the connector 20.Moreover since the sealing members 17 and 19 are resilient, a limited degree of both axial and radial relative movement is possible between the fuel pipe 10 and the connector 20. Relative axial movement between the fuel pipe 10 and the connector 20 is limited by the abutment of the largest diameter section 12 of the fuel pipe modified end portion 11 with the connector portion 22 and an apertured plate 24 attached to the end of the connector 20. The axial distance between the plate 24 and the connector portion 22 is greater than that of the section 12 in order to permit such relative axial movement. Thus by permitting a limited degree of relative movement between the fuel pipe 10 and the connector 20, the likelihood of the fuel pipe 10 cracking or fracturing as a result of fatigue is greatly reduced.

The connector 20 is provided with an annular channel 25 intermediate the duct 21 and the connector portion 22, and hence intermediate the sealing members 17 and 19, which is in communication with a drainage duct 26.

Consequently if the sealing member 1 9 should fail, any fuel which leaks therefrom passes into the annular channel 25 and thence into the drainage duct 26, which may be cited or instrumented to facilitate leak detection. Any fuel which may get past the annular channel 25 is prevented from leakage to the exterior of the fuel pipe 10/connector 20 assembly by the sealing member 17.

It will be seen therefore that the present invention provides a fuel pipe seal which has improved resistance to uncontrolled and undetected leakage and which permits a limited degree of relative movement between a fuel pipe and its associated connector, thereby reducing the possibility of the fuel pipe failing and therefore leaking as a result of fatigue.

Claims

1. A fuel system including a fuel pipe, a connector for the reception of one end of said fuel pipe and sealing means interposed between said fuel pipe and said connector, said sealing means comprising at least two annular axially spaced apart resilient sealing members which radially space apart said fuel pipe and said connector so as to permit relative movement therebetween, said connector being provided with means for draining any fuel from the space between said sealing members.

2. A fuel system as claimed in claim 1 wherein said at least two sealing members are of different diameters, the sealing member of smallest diameter being closest to the end of said fuel pipe, said fuel pipe and connector being so configured as to accommodate said at least two sealing members.

3. A fuel system as claimed in claim 1 or claim 2 wherein two of said sealing members are provided between the end of said fuel pipe and the position of said fuel draining means.

4. A fuel system substantially as hereinbefore described with reference to the accompanying drawing.