GB2449071A

GB2449071A - Fluid coupling

Info

Publication number: GB2449071A
Application number: GB0708784A
Authority: GB
Inventors: Thomas William Wright
Original assignee: Rolls Royce PLC
Current assignee: Rolls Royce PLC
Priority date: 2007-05-05
Filing date: 2007-05-05
Publication date: 2008-11-12
Also published as: GB0708784D0

Abstract

The fluid coupling comprises a male part, e.g. a gas turbine oil system pipe 2, a female part, e.g. an access in a container wall 6 of an oil reservoir 8, guiding means and retaining means. The male part 2 comprises a convex sealing surface 16 at its distal end and the female part comprises a concave sealing surface 28 at an inner region. The guiding means comprise inter-engaging parts on the male and female parts which when engaged prevent relative rotation of the male and female parts, e.g. diametrically opposite protrusions 18, 20 on the male part 2 locating in grooves in the female part. The retaining means, e.g. an externally threaded tube nut 42, engages a triangular flange on the wall 6 to hold the male part inside the female part and urge the two sealing surfaces 16, 28 into sealing contact. Locking means, e.g. a wire 58, may be provided to hold the retaining means in position during use by attaching to both the retaining means and either the male part or the female part.

Description

FLUID COUPLING

This invention relates to a fluid coupling. In particular the invention relates to an apparatus for maintaining a sealed fluid passage between a pipe and a receptacle.

Such an apparatus may find particular application as part of an oil system for a gas turbine engine. In a fluid system it is known to insert a pipe inside a receptacle and use a retaining nut to hold the two components in sealing contact. In such an arrangement the pipe end typically terminates in a dome shaped cap or ferrule which has an increased diameter to that of the pipe. The retaining nut is positioned around the pipe to engage both the back of the cap and the inside of the receptacle, and urge the cap face into sealing contact with the receptacle base. In some applications there is a risk that tightening the retaining nut twists the cap face relative to the receptacle base causing surface damage and potential loss of sealing integrity.

It is often necessary to lock the retaining nut in position to avoid it causing loss of sealing integrity by loosening during use, for example due to engine vibrations. As the pipe may twist, the retaining nut must be locked to the receptacle and not the pipe. In some applications access to the receptacle is limited and so it is difficult to lock the retaining nut in position.

It is an aspect of the present invention to provide a fluid coupling comprising a male part provided with a sealing surface at its distal end, a female part provided with a sealing surface at its inner end, retaining means to hold the two sealing surfaces in sealing contact, and guiding means comprising inter-engaging parts on the male and female parts which when engaged prevent relative rotation of the male and female parts.

In a preferred embodiment the fluid coupling further comprises a locking means for locking the retaining means relative to the male part.

The invention will now be described, by way of example only, with reference to the accompanying drawings in which: Figure 1 is a cross-section view of a fluid coupling in accordance with the present invention; Figure 2 is an axial view of the distal end of male part 2 of Figure 1; Figure 3 is a plan view of female part 4 of Figure 1; and Figure 4 is an axial view of the distal end of retaining means 42 of Figure 1.

In Figure 1 there is shown a fluid coupling from an oil system of a gas turbine engine comprising a male part, represented by a rigid pipe 2, and a female part, represented by a U-shape cross-sectioned receptacle 4. The pipe 2 provides a connection to the remaining oil system network, and the receptacle 4 provides an access point through a container wall 6 into an oil reservoir 8. When the male part is docked inside the female part oil may be transferred across the coupling and distributed around the engine.

The pipe 2 comprises a cylindrical shaft 10 and a dome shaped distal end forming a cap 12 with a flat backing face 14 and a convex sealing thrust face 16. As viewed more particularly in Figure 2, guiding means in the form of two diametrically opposite and rectangular-profile protrusions 18 and 20 extend outward and perpendicular to the axis of the pipe 2 from the side of the cap 12 at the corner between the backing face 14 and the thrust face 16. An aperture 22 is formed at the apex of the thrust face 16 through which fluid may pass from or into the pipe.

The U-shape cross-sectioned receptacle 4 has a base 24 with a flat inner surface 26 having a substantially concave depression formed at its centre comprising a circular inner sealing surface 28 and a cylindrical wall 30. The sealing surface 28 declines towards its centre where there is an opening to a duct 32 which transmits fluid from the reservoir 8 into the receptacle 4. Extending from the base 24 is a cylindrical annulus 34. As viewed more particularly in Figure 3, the inner surface of the annulus 34 is provided with receiving means in the form of two diametrically opposite and rectangular-profile axial grooves 36 and 38. The opposite end of the annulus 34 is formed with a radially inward flange 40 of substantially triangular cross-section.

A hollow cylindrical tube nut 42 provides retaining means and encircles the shaft 10 of the pipe 2. The tube nut 42 is formed with an externally threaded portion 44, which terminates in a retaining face 46 at the end adjacent to cap 12, and joins a turret portion 48 at the other end. As viewed more particularly in Figure 4, the distal end of the turret portion 48 is crenellated with merlons 50 to 56. Locking means are provided by a wire lock 58, which passes through two matching locking eyes 60 and 62 formed in merlon and the pipe 2 respectively.

To insert pipe 2 past the flange 40 and fully into the receptacle 4 the cap 12 must be orientated so that the grooves 36 and 38, and the protrusions 18 and 20 inter-engage.

When engaged in this configuration the protrusions 18 and 20 prevent relative rotation of the pipe 2 and the receptacle 4, and the thrust face 16 contacts the sealing surface 28 to align the aperture 22 with the duct 32 so that oil can flow between the reservoir 8 and the pipe 2. The tube nut 42 encircles the shaft 10 and is between the pipe 2 and the receptacle 4. The threaded portion 44 engages the flange 40, and the retaining face 46 abuts the backing face 14 to urge the thrust face 16 into sealing contact with the sealing surface 28. Applying a clockwise or anti-clockwise torque to the turret portion 48 causes the tube nut 42 to screw into or out of the receptacle 4. Screwing the tube nut 42 into the receptacle 4 increases the force with which the thrust face 16 bears against the sealing surface 28. The bearing force of the tube nut 42 is sufficient when the sealing contact between the thrust face 16 and sealing surface 28 ensures all oil passes across the coupling without any leakage into the receptacle 4. To avoid loss in sealing integrity caused by the tube nut 42 loosening during service the wire lock 58 is taut and attaches through eyes 60 and 62 to hold the tube nut in position and prevent it from unscrewing.

Although aspects of the present invention have been described with reference to the embodiments shown, it must be noted that modifications could be implemented without exercise of further inventive skill. Protrusions with alternatively shaped profiles could be used to achieve the same result as those disclosed and may be more suitable given the specifics of a particular application. It should be noted that if using alternatively shaped protrusions it might be necessary, or desirable, to change the profile of the cooperating grooves so that they inter-engage with the protrusions securely.

Furthermore, aspects of the geometry of the male and female parts may provide inter-engaging guiding means. For example, part of the distal end of the male part could be hexagonally shaped to engage with a cooperating hexagonal slot formed in the female part, and prevent relative rotation of both parts. Finally, it is to be understood that the present invention would be equally as effective with locking means for locking the retaining means relative to the female part.

Claims

A fluid coupling comprising a male part provided with a sealing surface at its distal end, a female part provided with a sealing surface at its inner end, retaining means to hold the two sealing surfaces in sealing contact, and guiding means comprising inter-engaging parts on the male and female parts which when engaged prevent relative rotation of the male and female parts.
2 A fluid coupling as claimed in claim I wherein the inter-engaging parts of the guiding means comprises at least one raised protrusion on the side of the distal end of the male part, and a cooperating receiving means on the female part.
3 A fluid coupling as claimed in claim 2 comprising diametrically opposite protrusions, and corresponding receiving means.
4 A fluid coupling as claimed in claim 3 comprising two diametrically opposite protrusions, and corresponding receiving means.
A fluid coupling as claimed in any preceding claim wherein the guiding means is positioned immediately behind the sealing surfaces.
6 A fluid coupling as claimed in any preceding claim wherein the retaining means comprises a tube nut that encircles the male part and is provided with an external thread which when engaged with the female part urges the sealing surfaces into sealing contact.
7 A fluid coupling as claimed in claim 6 wherein the opening of the female part is formed with an inward flange that engages the external tube nut thread.
8 A fluid coupling as claimed in claim 7 wherein the flange cross-section is substantially triangular.
9 A fluid coupling as claimed in claims 6, 7 and 8 wherein the tube nut head is crenellated.
A fluid coupling as claimed in any preceding claim further comprising a locking means for locking the retaining means relative to the male part.
11 A fluid coupling as claimed in claims 1 to 9 further comprising a locking means for locking the retaining means relative to the female part.
12 A fluid coupling as claimed in claims 10 and 11 wherein the locking means is a wire lock fastened through apertures formed in a wall of each locked component.
13 A fluid coupling as claimed in claim 12 wherein the wire of the wire lock is taut when fitted.
14 A fluid coupling as claimed in any preceding claim wherein the male sealing surface is substantially convex and the female sealing surface is substantially concave.
A gas turbine including a fluid coupling as claimed in any one of claims I to 14.
16 A fluid coupling substantially as hereinbefore described with reference to the accompanying drawings.