Seal for a joint or juncture – Seal between relatively movable parts – Relatively rotatable radially extending sealing face member
Patent
1981-07-22
1982-09-07
Ward, Jr., Robert S.
Seal for a joint or juncture
Seal between relatively movable parts
Relatively rotatable radially extending sealing face member
277 27, 277 70, 277173, F16J 1540
Patent
active
043480292
DESCRIPTION:
BRIEF SUMMARY
FIELD OF TECHNOLOGY
The present invention relates to a seal-ring structure of a seal-ring type shaft-sealing device which improves the floating characteristic and eliminates the non-uniformity in temperature during the operation.
BACKGROUND OF TECHNOLOGY
FIGS. 1 and 2 show the conventional seal-ring type shaft-sealing device for sealing a fluid such as a highly pressurized gas or liquid.
In the figures, the reference numeral (1) designates a rotating shaft; (2) designates a housing having side walls (2a), (2b) through which the rotating shaft (1) passes; (3) designates a seal ring formed by a pair of annular rings; (4) designates an antirotation pin secured to the seal ring (3) to prevent it rotation; (5) designates inlets for a sealing liquid which are provided radially in the outer surface of the seal ring at plural positions in order to seal a highly pressurized fluid, the inlets communicating with a single annular groove (6); (7) designates a gap formed between the seal ring and the rotating shaft (1); (8) designates an antirotation pin support formed in the housing (2); and (9) designates a annular space for feeding the sealing liquid radially which is also formed in the housing (2).
Operation of the conventional device having the structure described above will be explained.
The sealing liquid in the housing (2) passes through the inlets (5) of the seal ring (3) to fill the annular groove (6) and provides a liquid film (not shown in the figures) in the gap (7) formed between the rotating shaft (1) and the seal ring (3) and flows, on the one hand, to the sealed side (shown by the symbol G) and on the other hand, to a low pressure side as atmosphere (shown by the symbol A). The pressure (PS) of the sealing liquid is maintained slightly higher than the pressure PG of the fluid to be sealed (gas or liquid) whereby leakage of the fluid to be sealed to the lower pressure side is prevented. The seal ring (3), during operation, floats by hydrodynamic force, producing the liquid film, by the revolution of the rotating shaft (1) so that the seal ring operates in a non-contacting state, i.e. maintaining a gap (7) between itself and the rotating shaft (1).
In the conventional shaft-sealing device, the inner circumference of the seal ring (3) is manufactured a true circle while the seal ring generally operates eccentrically in relation to the rotating shaft (1) as shown by dotted lines in FIG. 3 whereby heat produced in the liquid film formed in the gap (7) by the revolution of the rotating shaft (1) is not uniformly distributed on the inner surface of the seal ring and the seal ring becomes oval shaped by thermal deformation as shown by the solid line in the figure. The minimum liquid film thickness (F) existed in non-thermal deformation is further reduced to the thickness (H) as shown in FIG. 3. This results in an excessive temperature increase in the inner surface of the seal ring (3) and contact with the rotating shaft (1) thereby having an adverse effect on the vibration of the shaft.
SUMMARY OF THE INVENTION
It is an object of the present invention to overcome the disadvantages of the conventional device and to provide a seal-ring type shaft-sealing device which provides a uniform temperature distribution in the inner surface of the seal ring by producing previously the inner circle of the seal ring in a predetermined oval shape and by fitting the seal ring into a housing in an inclined state so that the angle formed by the longitudinal axis of the ellipse and the gravity force direction of the seal ring in the revolutional direction of the rotating shaft is smaller than 90.degree. and which attains an excellent shaft-sealing function by reducing the difference between the maximum thicknesses of the liquid film produced between the seal ring and the rotating shaft.
In accordance with the present invention, a seal-ring type shaft-sealing device which provides a uniform temperature distribution in the inner surface of the seal ring by producing previously the inner circle of the seal ring in a predeterm
REFERENCES:
patent: 2971783 (1961-02-01), Laser
patent: 3132906 (1964-05-01), Sternlicht
patent: 3528666 (1970-09-01), Prampart
patent: 3756673 (1973-09-01), Strub
"High-Performance Seals", by Cawley et al., Machine Design, Apr. 1, 1971.
"Mating Materials and Environment Combinations for Specific Contact-and Clearance Type Seals", by Ruthenberg, ASLE Lubrication Engineering, vol. 29, Feb. 1973.
"The Influence of High Pressure Oil Seals on Turbo-Rotor Stability", by Kirk et al., ASLE Lubrication Engineering, vol. 22.
Masuda Takahiro
Oishi Norio
Shimazu Toshinari
Suganami Takuya
Mitsubishi Denki & Kabushiki Kaisha
Ward, Jr. Robert S.
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