Seal for a joint or juncture – Seal between relatively movable parts – Relatively rotatable radially extending sealing face member
Patent
1998-01-15
2000-11-07
Knight, Anthony
Seal for a joint or juncture
Seal between relatively movable parts
Relatively rotatable radially extending sealing face member
277370, 277390, 277396, 277397, F16J 1534
Patent
active
061424765
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a mechanical seal, especially to a mechanical seal which prevents leakage of sealed fluid when a sealed fluid pressure changes and fluctuation of pressure difference take places and further prevents the occurrence of floating failure of a seal ring caused by deposition and adherence of crystals or accumulation of scales at a seal portion.
2. Description of Related Art
In a conventional mechanical seal, there has been provided a groove for mounting a seal packing (o-ring and the like as a secondary seal) and also provided a small gap between a sealing face and the opening end of the groove. Where a sealed fluid (hereinafter referred to as fluid A) contains solid substances or the fluid tends to separate out crystals, solid deposits tend to adhere to the small gap, and as a result the seal ring fails and leakage of the sealed fluid occurs, resulting in a very short life of the mechanical seal.
Accordingly, a mechanical seal is not used for a fluid containing crystals or solid substances which adhere to a seal ring, or otherwise a mechanical seal is used while flushing the sealing portion constantly with clean fluid.
Furthermore, a balance factor can be established freely with respect to a fluid pressure of fluid A located on one side of the sealing face, while a balance factor with respect to a fluid pressure of an opposing fluid (hereinafter referred to as fluid B) shall be designed in a limited range which is determined with regard to the balance factor of fluid A and a diameter of a seal packing. It is therefore an object of the present invention to provide a novel mechanical seal so that a balance factor of a mechanical seal can be easily established depending on the fluctuation of sealing pressure and to enhance the capability of the mechanical seal.
SUMMARY OF INVENTION
In order to achieve the above objects, the mechanical seal according to the present invention is characterized in that a seal ring is equipped with two seal packings so as to establish two balance diameters and a balance factor of the mechanical seal is provided separately and freely for two opposed fluids at a sealing face of a mechanical seal.
This invention also provides a mechanical seal having a means to prevent the adherence of crystals and solid substances in a packing groove and in the vicinity thereof. The means includes removing a wall at a sealed fluid side of a packing groove which secures a seal packing.
The pressure in the space between the two seal packings can be reduced to atmospheric pressure or below by means of a vacuum path provided between the two seal packings.
The seal ring may be divided into two parts between the two seal packing while interposing a packing between the divided two parts so that the seal ring may become deflective in a radial direction.
The balance factor of a mechanical seal is determined depending on a sealing face area and a pressure receiving area. The pressure receiving area is determined on the basis of the outer diameter or the inner diameter of the seal packings, namely the balance diameter. Accordingly, in a mechanical seal provided with a seal packing on both sides of fluid A and fluid B respectively, as in the present invention, a balance diameter and a balance factor can be established separately and freely for each of the two fluids which are opposed at the sealing face.
Furthermore, by removing a wall at the sealed fluid side of the packing groove for securing a seal packing and eliminating the small gap at which crystals or solid substances tend to accumulate, the increase of resistance caused by clogging of crystals or solid substances is eliminated and thus the floating property of the seal ring is not impaired. Accordingly the flexibility of the sealing face is improved and leakage of the sealed fluid is prevented.
The seal ring, divided into two parts between the two seal packings while interposing a watertight packing between the divided two parts, can deflect in a radial direction, so that ti
REFERENCES:
patent: 3188095 (1965-06-01), Van Vleet
patent: 3420535 (1969-01-01), Hershey
patent: 3589738 (1971-06-01), Tracy
patent: 4094512 (1978-06-01), Back
patent: 5388843 (1995-02-01), Sedy
patent: 5711532 (1998-01-01), Clark et al.
Knight Anthony
Peavey Enoch E.
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