Seal for a joint or juncture – Seal between fixed parts or static contact against... – Contact seal for other than internal combustion engine – or...
Reexamination Certificate
1998-07-09
2001-07-24
Sandy, Robert J. (Department: 3626)
Seal for a joint or juncture
Seal between fixed parts or static contact against...
Contact seal for other than internal combustion engine, or...
C277S605000
Reexamination Certificate
active
06264207
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention relates to a seal for sealing joints between a higher-pressure space and a lower-pressure space on parts and components to be sealed off, in particular on ducts or conduits comprising concrete pipes and shaft structures.
A seal a primary seal in the form of a taper sliding ring and a comprising secondary seal in the form of an axially projecting annular bead with a high degree of flexibility, is known from U.S. Pat. No. 3,417,942 Jornhagen subdivided in a latticework-like fashion and which has air-filled cavities without an outlet opening. The taper sliding ring is carried on the cylindrical surface of the spigot end of a pipe while the annular bead is disposed on the radial front face of that spigot end. Upon assembly with the socket end of a pipe, the socket slides over the inclined surface of the taper sealing ring and compresses it so as to afford a pressure profile with a rising pressure flank. The annular bead as the secondary seal is compressed to a greater or lesser degree when the pipes are fitted together, the pressures which occur in that situation being low because otherwise the pipes are pushed apart by that pressure. Accordingly, the sealing action with annular bead seals is not very great, and not adopted for a relatively great pressure drop. When using taper sliding rings as the primary seal, the sealing action depends on the width of contact and the surface pressure, which in turn are very heavily dependent on the production tolerances of the pipes which are to be fitted one into the other, such tolerances determining the width of the gap which is to be sealed off. If the gap is of great width, then the sealing width is small and the contact pressure is low while a narrow gap means that the sealing width and the contact pressure admittedly become high, but the risk of the seal being squashed or the risk of cracks being formed in the socket of the pipe or the spigot end thereof can become great.
U.S. Pat. No. 522,413 discloses a seal for sealing the expansion gap between concrete portions. The seal includes so-called chevron walls which, by virtue of their Y-shaped configuration, bend slightly and guarantee an approximately uniform contact pressure, irrespective of the width of the gap. It is not possible to provide sealing integrity between a high-pressure space and a low-pressure space.
Seals with a cavity as a pressing means are known per se (German Provisional Applications 38 15 142 and 42 36 368). In such an arrangement, a cavity disposed in the seal body is charged with liquid, possibly setting pressing agent under high pressure, small pipe portions of which are passed through the precast concrete parts being used for that purpose. The cavity cannot be used as a test space to establish sealing integrity of the seal.
It has long been known for expansion joint seals to be provided with cavities which by virtue of high internal pressure result in an increased contact pressure on the part of the seal (German published application 551 816).
Arranging slide lugs on the inclined surface of sliding seals is known from Germany published Application No. 36 01 757.
SUMMARY OF THE INVENTION
It is an object of the invention to provide a seal for sealing gaps at parts and components to be sealed off, in which the contact width and the contact pressure of the seal can be selected and in which the gaps or joins to be sealed off do not have to satisfy excessive tolerance demands. The invention seeks to provide that the contact pressure of the seal can possibly be proportionally increased as a result of internal pressure.
In accordance with a second aspect of the invention the seal is adapted to be self-lubricating and/or is adapted to automatically take up its sealing effect.
In accordance with a third aspect of the invention the invention seeks to provide that the seal can be checked and activated (post-sealed).
The present invention provides a seal body which preferably has mutually parallel sides with which it lies in the gap between the components to be sealed off, as a primary seal. Cavities are so disposed in the seal body that a support structure is afforded in the manner of a latticework, but with comparatively thick braces or struts which do not bend but which are widely spaced. If the seal is compressed in the gap which is to be sealed off, certain regions act as compressive struts and others as tensile struts. The pressure struts can yield and expand in the direction of the cavities, with the tensile struts being subjected to a tensile force. That provides internal stress distribution in the seal, which is better in comparison with a solid body, in order to seal off gaps and joints of different widths, without the contact pressure of the seal against the components in that situation experiencing an excessive increase. In that case, the seal body can be made up from different materials involving different hardnesses, and more specifically the seal body can comprise on the outside a relatively soft material in order to be able better to adapt to the roughness and unevenness of parts or components to be sealed off, while the tensile and pressure struts in the core region of the seal body should comprise firmer and harder material in order to ensure that the seal provides the necessary contact pressure against the parts or components to be sealed off, in order to achieve the condition of sealing integrity. The contact pressure of the seal against the parts to be sealed off can be further increased by the cavities of the seal being communicated with the space which is at a higher pressure, so that the pressure which is to be sealed off in itself has a supporting effect in relation to the seal.
When dealing with pipes the seal body can either be pulled on to the spigot end or it can be inserted into or concreted into the socket bell end.
When dealing with such pipes which are to be fitted one into the other, it is possible to provide on the seal body cavities (pockets) which can have a lubrication function. In quite general terms it is possible to use cavities or recesses which contain a post-sealing material in gel or solid form (that is to say those which become active and thus provide an additional sealing effect, upon moisture or water contact).
In the embodiment in the form of a twin or duplex seal, sealing integrity visual checks or sealing integrity initial tests and repetition test procedures can be carried out with air or water. The testing operation can be performed individually For each pipe joint or (when a suitable procedure is employed) it can be implemented centrally for an entire run of pipes. In addition, if a leak is found, an annular space which is arranged between two seal bodies can be filled with post-sealing material. Direct access to that annular space (testing and post-sealing space) can be such that there is no weakening due to additional bores being formed in the pipes which are joined together.
REFERENCES:
patent: 2615741 (1952-10-01), Nathan
patent: 3173699 (1965-03-01), Nathan
patent: 3643965 (1972-02-01), Nicholson
patent: 3762826 (1973-10-01), Bowman
patent: 4667966 (1987-05-01), Oehrle et al.
patent: 4743036 (1988-05-01), Nicholas
patent: 6003873 (1999-12-01), Solberg
Sandy Robert J.
Schwing Karlena D.
Temko Charles E.
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