Seal for a joint or juncture – Seal between relatively movable parts – Relatively rotatable radially extending sealing face member
Patent
1995-03-29
1996-09-17
Cummings, Scott
Seal for a joint or juncture
Seal between relatively movable parts
Relatively rotatable radially extending sealing face member
277215, F16J 1532
Patent
active
055561128
DESCRIPTION:
BRIEF SUMMARY
The invention relates to a shaft sealing ring which comprises an annular holder and an annular sealing part which is made up of a sealing lip extending to the surface of the shaft against the pressure difference to be sealed and of an approximately radially extending connecting section which connects the sealing lip to the holder. In the case of a known seal of this kind (EP-A 0 133 928), the connecting section is not of stiffer design than the sealing lip in order to allow it to bend easily. This ensures that the sealing part can be molded as a radial disc and assumes the.typical sloping lip orientation against the pressure difference to be sealed only through deformation during installation. It is not known how the known seal deforms under a pressure difference. It must be assumed that, under the pressure difference to be sealed off, the sealing lip, which encloses an acute angle with the surface of the shaft, undergoes a flexure which tends to reduce said angle. It must furthermore be assumed that the sealing part including the connecting section undergoes an axial deformation toward the low-pressure side under the pressure difference to be sealed. Since, as a result, the orientation of the connecting section tends even further towards the radial direction, this deformation too also tends to reduce said angle between the sealing lip and the surface of the shaft. As a result, the known seal is therefore found to undergo a reduction in the angle at which it rests on the surface of the shaft over the pressure range to be sealed. The sealing conditions are thereby changed in a disadvantageous way. This is particularly disadvantageous in the case of a material which, like polytetrafluoroethylene, has a tendency for what is referred to as cold flow. This term denotes that the material is subject to progressive permanent deformation under the prolonged action of force. In the case of the known seal, the reduction in the angle between the sealing lip and the surface of the shaft, particularly under the action of cold flow, leads to a disadvantageous enlargement of the surface by which the lip rests on the surface of the shaft. If the sealing lip is provided with a predetermined cross-sectional geometry so as to form a predetermined contact surface, this geometry is lost as a result of the deformation. At the same time, the sealing pressure rises, the sealing gap becomes smaller and the heat generated therein rises, something which can put the sealing lip at risk since, because of the flexibility or elasticity required, it is generally composed of a material which is sensitive to high temperatures. The loss of the predetermined cross-sectional geometry can furthermore have the effect that the sealing lip no longer rests on the mating sealing surface by the annular surface preformed for this purpose with a particular geometry but then rests on the mating sealing surface only by an edge of this sealing surface, and this can lead to increased frictional stress on and damage to the mating sealing surface.
According to the invention, these disadvantages are reduced or eliminated.
The mode of action of the features of the invention is based on the fact that the lip and the connecting section deform in opposite directions under the pressure difference. In the case of the connecting section, this deformation is distinguished by the fact that at least one part of the connecting section is deformed beyond the radial plane toward the low-pressure side or, in other words, that a part of the connecting section situated radially further in assumes a position nearer to the low-pressure side than a part of the connecting section situated radially further out. This deformation has the effect that the radially inner region of the connecting section not only shifts axially but also slightly outward in the radial direction. This means that that end of the lip which is connected to said connecting section is moved away from the mating sealing surface. The deformation movement of the lip toward the mating sealing surface is thereby c
REFERENCES:
patent: 4344631 (1982-08-01), Winn
patent: 4995621 (1991-02-01), Devouassoux et al.
patent: 5411273 (1995-05-01), Pietsch et al.
Cummings Scott
Martin Merkel GmbH & Co KG
LandOfFree
Shaft sealing ring with flexible hinged sealing lip does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Shaft sealing ring with flexible hinged sealing lip, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Shaft sealing ring with flexible hinged sealing lip will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-408748