Seal for a joint or juncture – Seal between relatively movable parts – Relatively rotatable radially extending sealing face member
Patent
1993-10-29
1995-07-18
DePumpo, Daniel G.
Seal for a joint or juncture
Seal between relatively movable parts
Relatively rotatable radially extending sealing face member
277 27, 277177, F16J 1532
Patent
active
054334527
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The invention concerns a sealing device between two concentric machine components which are movable with respect to each other, with a first sealing ring made from tough elastic plastic and with a biasing element made from a resilient elastic material which radially biases the sealing ring, whereby the first machine component exhibits a groove which accepts the sealing ring and the biasing element and whereby the sealing ring lies on a peripheral surface of the second machine component.
BACKGROUND OF THE INVENTION
A sealing device of this kind has become known through DE-AS 23 25 000.
The known sealing device is characterised by an extremely small leak rate and a very long lifetime. Occasionally, however, elevated leak rates have been observed.
The underlying purpose of the invention is therefore to improve the sealing effect of the known sealing device and to increase its lifetime.
This purpose is achieved in accordance with the invention in that, in the pressure-less state, the sealing ring, as viewed in the radial direction with respect to the axis of the second machine component, is at least partially separated from a low pressure side of the groove, in that the sealing ring is pivotable towards the low pressure side under the application of pressure and/or through the frictional force between the sealing ring and the peripheral surface, and in that the sealing ring forms a sealing edge with respect to the peripheral surface.
The sealing device in accordance with the invention thereby has the essential advantage that it can be mounted without a prominent sealing edge. The cross-sectional shapes of this type of sealing ring can be simple since pressure loaded and unloaded surfaces can adjust themselves relative to the sealing edge in accordance with the degree of pivot of the sealing ring from the pressure-less into the pressure-loaded state.
If the sealing device is utilized in the pressure-less state and for machine components which move back and forth with respect to each other, the sealing ring pivots from an installed position into a working position in such a fashion that it always tilts on the groove edge, formed on the stationary machine component, which is opposite to the direction of motion of the moving machine component. The low pressure side N corresponds in this case to the side to which the sealing ring is pivoted.
The sealing ring in accordance with the invention is biased by means of a biasing element and its surfaces directed towards the groove sides form an acute angle therewith which in a pressure-less state lies between 10.degree. and 40.degree..
If the sealing ring is symmetrically constructed, it is also easy to mount since attention must not be paid to the direction of installation. The sealing ring, in the case of symmetric configurations, can be subjected, in a direction independent fashion, to a hydraulic pressure in such a fashion that the pivoting process in accordance with the invention establishes itself.
The particularly advantageous application of the sealing configuration according to the invention as a shaft and piston seal has been confirmed by long-running experiments. The durability is substantially increased compared to known sealing devices for reduced leak rates.
If the sealing ring is manufactured from polytetrafluoroethylene, a sealing ring which is symmetric in the pressure-less state can be formed into an asymmetric sealing ring in the pressure-loaded state. Thereby the sealing ring material flows into free spaces given by diagonal surfaces, the free spaces establishing themselves due to the pivoting of the machine component in the groove.
Sealing rings made from polyurethane are particularly suitable for piston seals because they can be subjected to alternating pressure from different directions and also exhibit a very stable shape when pressure-loaded. The sealing device in accordance with the invention is also applicable as a rotational seal. Towards this end a rotational movement with the moving mechanical parts is compensated f
REFERENCES:
patent: 3909016 (1975-09-01), Traub et al.
patent: 4911455 (1990-03-01), Edlund
patent: 4917390 (1990-04-01), Lee
patent: 5104131 (1992-04-01), Edlund et al.
patent: 5249813 (1993-10-01), Botto
Edlund Roy
Jordan Holger
Poethig Rolf
Busak & Luyken GmbH & Co.
DePumpo Daniel G.
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