Seal for a joint or juncture – Seal between relatively movable parts – Relatively rotatable radially extending sealing face member
Patent
1992-11-04
1994-06-28
Cuchlinski, Jr., William A.
Seal for a joint or juncture
Seal between relatively movable parts
Relatively rotatable radially extending sealing face member
277167, 277203, F16J 1516
Patent
active
053240472
DESCRIPTION:
BRIEF SUMMARY
This invention relates to a thread seal, for use with a threaded member, of the type comprising a helical rib with axially staggered ends joined by a transverse thread bridging member, the rib serving to cooperate with the thread groove of the threaded member so as to form a seal.
Such seals are often used in conjunction with ball thread actuator systems to prevent leakage of grease from the system. The systems are used in aircraft to set the positions of flying surfaces such a landing flaps and are often exposed to the elements. It will therefore be appreciated that the seal must also prevent the ingress of dirt and water. The seals have therefore been made to closely conform to match the shape of the groove thread in order to provide an efficient seal. However such arrangements require a considerable expenditure of power in order to overcome the friction between the seal and the threaded member. This problem is further compounds by the seal absorbing grease and swelling.
According to one aspect, the invention consists in a thread seal for forming a seal about a threaded member comprising at least one rib for sealingly engaging a thread groove and at least one axially extending thread-bridging member connected between adjacent end portions one rib or a pair of ribs to form a complete circumferential seal about the threaded member wherein the rib or ribs each have a tapering cross-section to project radially into the groove to form a lip seal over a limited axial width of the groove throughout the greater part of the circumferential length of the rib.
Because of the limited area of contact between the rib and the thread groove, the frictional force between them is reduced. Furthermore, the area of contact of the end portions with the threaded member can be limited to that lying axially between the lip seal formed by these end portions.
In a first embodiment of the invention, a single helical rib, which extends about the full circumference of the threaded member, has its axially staggered end portions joined by a bridging member. In a second embodiment, a plurality of ribs are provided each extending only part of the way about the full circumference with their end portions axially adjacent one another and joined by a bridging member. The second embodiment of the invention is preferred for use with a threaded member having a multistart thread, the ribs engaging adjacent grooves of the thread.
According to another aspect, the invention consists in a seal assembly adapted for use with a threaded member, comprising a thread seal and an ice chipper, the thread seal comprising at least one helical rib having axially staggered end portions which end portions are joined together or to end portions of an adjacent rib or ribs by at least one transverse thread bridging member so as to cooperate with the threaded member to form a complete annular seal therewith, and the ice chipper being adapted to extend over a short length of the thread of the threaded member and being located circumferentially adjacent to the bridging member of the seal so as to lie within the axial length of the seal.
According to a further aspect of the invention, there is provided a thread seal for forming a circumferential seal about a multi-threaded member having formed therein a plurality of thread grooves, the seal comprising at least two ribs in sealing engagement with at least two of said grooves, and with adjacent end portions of the ribs being joined by a transverse thread-bridging member to complete the seal.
By forming the seal with ribs engaging different grooves of the threaded member it is possible to produce a thread seal which is more axially compact that would otherwise be possible.
A specific embodiment of the invention will now be described, by way of
example only, with reference to the drawings in which:
FIG. 1 shows a partial section through part of a ball thread actuator system employing a thread seal in accordance with the invention;
FIG. 2 is a view of the bridging member of a thread seal removed from its carrier;
FIG. 3
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Organ Alan H.
Smith Robert M.
Cuchlinski Jr. William A.
Cummings Scott W.
Dowty Seals Limited
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