Elastic sealing element in the form of bellows

Details Elastic sealing element in the form of bellows Elastic sealing element in the form of bellows

1999-03-01

2001-10-30

Sandy, Robert J. (Department: 3626)

Seal for a joint or juncture

Seal between relatively movable parts

Relatively rotatable radially extending sealing face member

C277S552000, C277S634000, C403S051000

Reexamination Certificate

active

06308959

ABSTRACT:

FIELD OF THE INVENTION
The present invention pertains to an elastic sealing element in the form of bellows for sealing the contact surface between at least two components movable in relation to one another with low-elasticity contact zones on the movable components, with a deformation zone of an elasticity higher than that of the contact zones, which is located between the contact zones and defines a chamber for accommodating lubricants on its inner side facing the movable components, and with an overpressure relief device.
BACKGROUND OF THE INVENTION
Sealing elements of this type have been known from, e.g., DE 196 34 444 A1 and are used in many areas of mechanical engineering, e.g., in automotive engineering. The above-mentioned document discloses a ball connection arrangement, in which an overpressure relief device is present, which is designed in the manner of a valve. An opening in an elastic sealing element, which opening connects the interior of a lubricant chamber to the outside air, is covered by a retaining ring here. If the pressure inside the lubricant chamber rises above a predetermined value as a consequence of a rise in the temperature of the lubricant, the pressing forces of the retaining ring are no longer sufficient to close the connection opening of the sealing element, so that lubricant can escape between the retaining ring and the sealing element at a corresponding overpressure.
The design of the overpressure relief structure disclosed in the document cited is disadvantageous because the retaining ring needed to seal the relief opening is displaceable in relation to the sealing element and also must be made as a slotted ring for reasons of mounting. Due to these properties dictated by the design, it may happen that the slot of the retaining ring is positioned exactly over the opening for relieving the overpressure. The consequence of this is that lubricant can escape unhindered to the outside even under normal pressure in the lubricant chamber or there is a possibility that contaminants can enter the lubricant chamber from the outside. Moreover, such retaining rings tend to fatigue or to have their function reduced at least partially, e.g., due to corrosion.
SUMMARY AND OBJECTS OF THE INVENTION
The primary object of the present invention is to provide an elastic sealing element that guarantees reliable sealing at any time and under all operating conditions and has, moreover, an overpressure relief means that operates reliably at any time, can be manufactured easily and at a low cost and offers safety against errors in mounting.
This object is accomplished according to the present invention by the overpressure relief structure being arranged in the area of one of the low-elasticity contact zones, by which the sealing element is in contact with the components to be sealed, which are movable in relation to one another, and by having at least one relief opening connecting the lubricant chamber to the outside of the sealing element and a closing element covering this relief opening; wherein the closing element is made in one piece with the sealing element and wherein the closing element closes the relief opening up to an overpressure limit in the lubricant chamber due to the intrinsic elasticity of the material of the sealing element.
The one-piece design of the closing element with the sealing element reliably prevents any error in mounting as they may occur in the case of the design according to the above-mentioned document, because additional components of the overpressure relief means of the sealing element are not present. Moreover, the one-piece design can be manufactured simply and at a low cost.
The relief opening may be designed as circular slots, wherein the depth of the slots is essentially half the wall thickness of the sealing element in the area in which the overpressure relief structure is arranged. The lubricant chamber may be connected to the slot by at least one hole. A plurality of the holes, which connect the lubricant chamber with the slot may be arranged on at least one concentric radius.
The relief opening may be designed as a slot. This slot is arranged in a partial area of the circumference of the sealing element and connects the lubricant chamber directly to the outside of the sealing element. A plurality of slots may be arranged as relief openings over the circumference of the sealing element.
The various features of novelty which characterize the invention are pointed out with particularity in the claims annexed to and forming a part of this disclosure. For a better understanding of the invention, its operating advantages and specific objects attained by its uses, reference is made to the accompanying drawings and descriptive matter in which preferred embodiments of the invention are illustrated.


REFERENCES:
patent: 3208290 (1965-09-01), Mathues et al.
patent: 3248955 (1966-05-01), Templeton
patent: 5568930 (1996-10-01), Urbach
patent: 196 34 444 A1 (1997-02-01), None

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