Seal for a joint or juncture – Seal between relatively movable parts – Circumferential contact seal for other than piston
Patent
1997-01-10
2000-11-21
Knight, Anthony
Seal for a joint or juncture
Seal between relatively movable parts
Circumferential contact seal for other than piston
277566, 277916, 416174, 416205, 416500, F16J 1532
Patent
active
061491632
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to ring seals, in particular, ring seals having a plurality of sealing lands.
BACKGROUND OF THE INVENTION
Multi-landed sealing rings are known, for example, as disclosed in British patent application No. GB-A-2163498. Known ring seals suffer problems of intermittent or poor sealing contact when subjected to shocks and vibrations. Such problems typically arise in the field of aeronautics particularly in hubs of aircraft propellers.
SUMMARY OF THE INVENTION
The present invention provides an assembly comprising relatively rotating and vibrating parts and a sealing ring for sealing between the parts, the sealing ring having a plurality of sealing lands, the shape and configuration of the lands being selected so that frequencies of natural resonant vibration of at least one of the ring or lands is not a frequency of vibration applied to the ring in use. Increasing the thickness of a sealing land has the effect of increasing its resonant frequency. Furthermore, the height of the sealing lands determines the squash force, i.e. pre-compression, which the ring will experience when- forced into position between the rotating parts. Increasing the pre-compression has the effect of increasing the resonant frequency of the land away from the frequency or range of frequencies to be avoided.
The resilience of the material of which the sealing land is made can also be selected so as to ensure that the resonant frequency of the sealing ring and its lands take the desired values.
The preferred sealing ring is shaped, configured, and prestressed in situ, so that its resonant frequencies are well away from the frequencies of vibration of the rotating parts occurring during constant running. The resonant frequencies of at least one of the ring or land can also be selected so as to be away from the vibration frequencies occurring during start-up and/or shutdown of a propeller.
The preferred sealing ring has both outwardly-directed lands and inwardly-directed lands. There are more lands in one direction than the other. Preferentially, there is a greater number of lands directed outwardly, ensuring that the sealing ring rotates with the rotating outer part. Furthermore, having fewer inwardly-directed lands ensures that there is reduced friction and wear between the relatively rotating sealing ring and the inner part.
Preferably, the outwardly-directed sealing lands comprise at least one central land flanked by outer lands, the at least one central land preferably has a reduced height compared to the outer lands. In consequence, the at least one central land is less pre-compressed than the outer outwardly-directed lands when the sealing ring is fitted between propeller parts. This has the advantage of making the more central land or lands less likely to collapse, and so provides a sealing ring of increased stability. Furthermore, having a central land or lands of reduced height ensures there is less friction against the propeller outer part. This is advantageous because lubricant is less likely to reach the central lands than the outer lands.
BRIEF DESCRIPTION OF THE DRAWINGS
A preferred embodiment of the invention will now be described by way of example with reference to the drawings, in which:
FIG. 1 is a side view of a sealing ring according to the present invention;
FIG. 2 is a cross-sectional view along the line 2--2 shown in FIG. 1;
FIG. 3 is an enlarged cross-sectional view of part of the ring as shown in FIG. 2; and
FIG. 4 is an enlarged cross-section view, showing dimensions, of the ring part shown in FIG. 3; and
FIG. 5 is a cross-sectional view of the sealing ring shown in FIG. 4, in position with a blade root and hub port.
BRIEF DESCRIPTION OF THE PREFERRED EMBODIMENTS
As shown in the figures, the sealing ring 1, which of rubber material, includes three outwardly-directed sealing lands 2,4,6 and two inwardly-directed sealing lands 3,5. Thus the sealing ring 1 has an approximate W-shaped cross-section. The heights of the sealing lands 2,3,4,5,6 are chosen s
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patent: 5626520 (1997-05-01), Mazziotti
Brown Thomas Noel
Parker Stephen John Bowen
Beres John L.
Dowty Aerospace Gloucester Limited
Knight Anthony
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