DE8709722U1 - Threaded plug for liquid-tight sealing of a hole - Google Patents

Description

•Hö'nneldrc Hoffmann

Am Eichenrain 22

7070 Schw.Gmünd-Lindach

Threaded plug for liquid-tight sealing of a hole

The invention relates to a threaded plug having the features of the preamble of claim 1.

Threaded plugs of this type are already known. Such plugs are used on a large scale, for example, to seal holes with internal threads in prefabricated, oil-filled gear units or hydraulic units in an oil-tight manner during shipment to the end user. The plugs are intended to be used as leak protection only and are only used once, i.e. they are discarded at the destination after removal from the device in question and are not reused.

With such use, it is important that a reliable seal is achieved in the most cost-effective way possible. The known plugs of the type mentioned above do not meet these requirements. A secure seal can only be guaranteed if the sealing surface on the edge of the hole opening is very carefully machined.

The invention is based on the object of creating a plug of the type in question which ensures perfect sealing even in conjunction with less carefully designed sealing surfaces.

This object is achieved according to the invention by a threaded plug which has the features of claim 1. In this solution, a labyrinth seal is created by the presence of the second sealing lip which surrounds the opening edge of the bore and runs alongside the first sealing lip at a distance from the latter. Even with relatively roughly machined ^sealing surfaces on the opening edge, a reliable seal is thus achieved without the need for additional, separate sealing rings, which is particularly economically disadvantageous with "disposable plugs".

; The plug according to the invention can be injection-molded from plastic,

In a preferred embodiment, the height of the sealing lips measured in the axial direction of the plug is chosen to be unequal. If, for example, the sealing lip located radially further out protrudes further from the ring surface than the inner sealing lip, then when the plug is screwed tight, the radially outer area of the fleece-like extension of the plug, i.e. the least rigid part, first clings to the edge of the opening. This allows the most easily deformable part of the plug to adapt to irregularities in the sealing surface before the inner sealing lip is pressed against the sealing surface, thus preventing further deformation due to the supporting effect of the inner sealing lip.

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The invention is explained in detail below using an embodiment shown in the drawing.

Show it:

Fig. 1; a view of the embodiment looking towards the threaded shaft and

Fig. 2: a broken drawn longitudinal section of the embodiment.

A plug shown in the figures, which is injection-molded in one piece from plastic, has a threaded shaft 1, a flange-like extension 3 and a head part 5, which is provided in the usual way with a polygon (not shown) or a transverse slot, which is intended for the engagement of a screwing tool.

The annular surface 7 of the extension 3 facing away from the head part 5 forms an upper sealing surface for interaction with a sealing surface on the opening edge of a respective bore, with the internal thread of which the threaded shaft 1 of the plug can be screwed.

As can be clearly seen in particular from Fig. 2, two sealing lips formed in one piece with the ring surface 7 are provided, namely an outer first sealing lip 8 and a radially further inner second sealing lip 9. Both sealing lips 8 and 9 are designed like ribs and form projections protruding from the plane of the ring surface 7 in the axial direction, which run concentrically to the round threaded shaft 1 and surround it without interruption.

As shown in Fig. 2, the sealing lips 8 and 9 are wedge-shaped in cross-section, with the wedge tip in the undeformed state being intended for linear contact with the sealing surface at the opening edge of the bore. It is understood that the sealing lips 8 and 9 could be shaped in such a way that they also form a wider contact surface instead of the wedge tip facing the sealing surface.

In the embodiment shown, the outer sealing lip 8 has a greater axial height than the inner sealing lip 9, the difference being indicated in Fig. 2 with h.

Claims (5)

PROTECTION CLAIMS 1) Threaded plug for liquid-tight sealing of a bore, which has a flat sealing surface on its outer opening edge, which is intended for interaction with an annular surface which is formed by a side surface of a fleece-like extension of the threaded plug and which has a sealing lip formed integrally with it, which is designed in the form of a rib projecting from the annular surface in the axial direction. characterized in that on the annular surface (7) there is a second sealing lip (9) which runs parallel to the sealing lip (8) and is designed as an axial projection which is integral with the annular surface (7). 2) Threaded plug according to claim 1, characterized in that the sealing lips (8 and 9) on the annular surface (7) run concentrically to the circular threaded shaft (1) of the plug. 3) Threaded plug according to claim 1 or 2, characterized in that both sealing lips (8 and 9) are at least approximately wedge-shaped in cross section. 4) Threaded plug according to one of claims 1 to 3, characterized in that the radially further outward sealing lip (8) measured in the axial direction of the plug has a greater height than the radially further inward second sealing lip (9). 5) Threaded plug according to one of claims 1 to 4, characterized in that it is injection-molded from plastic. In the claims, please put the reference numbers given above in parentheses.