Pipe joints or couplings – With fluid pressure seal – Flexible lip
Reexamination Certificate
1999-11-04
2001-01-09
Browne, Lynne H. (Department: 3629)
Pipe joints or couplings
With fluid pressure seal
Flexible lip
C285S370000, C285S379000
Reexamination Certificate
active
06170883
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a tubular element for use in a fluid-conducting duct system, in particular a ventilation duct system, and a method for manufacturing the tubular element.
BACKGROUND ART
When connecting fluid-conducting duct elements, especially in ventilation duct systems, it is important that the joints between the tubular elements be sufficiently sealed. U.S. Pat. No. 3,955,834 disclosed various modes of providing sealing means in the joint between a tube connector inserted in and interconnecting two tubes. FIGS.
3
-
9
and of this U.S. patent of 1976 show how an external, circumferential, flexible sealing ring having L-shaped cross-section is mounted at the end of a tubular element. The sealing ring is placed with its base abutting the outer surface of the tubular element, whereupon the free end portion of the tubular element is bent rearwardly outwards and turned back towards the wall of the tubular element. The sealing ring has a sealing lip radially extending away from the base and adapted to seal against an inner surface of an outer tube, in which the tubular element is inserted (see FIG.
8
).
This basic method of mounting the sealing ring at the end of a tubular element is still used in practice, as is shown in the Swedish-language catalogue “Veloduct®, Cirkul{umlaut over (a)}rt kanalsystem” issued in 1997 by ABB Ventilation Products AB, Division Veloduct. On page 2 of this catalogue, there is shown how a sealing ring with L-shaped cross-section is fastened by the bonding and clamping operation described above. This known technique, which is schematically shown in
FIG. 1
of the appended drawings, has however several disadvantages which will be related below.
The base of the L-shaped sealing ring is placed on an annular, circumferential step which protrudes radially outwards. This step leads to various drawbacks related to the mounting of the sealing ring as well as the structure of the sealing ring and its manufacture. When mounting the sealing ring on the tubular body, it is difficult to put the base on the raised step. Normally, this is a manual operation and the person mounting the ring often has to adjust the sealing ring on the raised step before the bending operation. Due to the raised step, the sealing ring has a tendency to slide inwardly on the tubular body during the bending of the end portion of the tubular body. This sliding movement may jeopardize the bending and clamping operation and thereby prevent safe fastening of the sealing ring. The bulge on the front end of the sealing ring base is normally not enough to prevent this sliding, especially in cases where the sealing ring material is relatively soft.
In practice, it has also been found that this known L-shaped sealing ring has special drawbacks for tubes of a large diameter, say exceeding about 300 mm. For tubular elements of such a large diameter, the radial dimension of the sealing lip is larger than the axial dimension of the base. Such sealing rings have a tendency to “tilt” about 90°, which means that the sealing ring is abutting the wall of the tubular body whereas the sealing ring base is directed radially outwards from the tubular wall. This misplacement has to be corrected manually in mounting.
The bulge at the free end of the sealing ring base makes it difficult to produce the sealing ring which consists of rubber. Due to the bulge, special tooling has to be used which involve specific drawbacks. The bulge makes it hard to achieve proper release from the mould. Especially when the sealing ring is injection moulded, the bulge is disadvantageous.
Thus, there is a need for a tubular element having improved sealing means, as well as a new method for manufacturing such a tubular element.
SUMMARY OF THE INVENTION
An object of the present invention is to eliminate the disadvantages mentioned above and to provide a tubular element with improved sealing means.
A further object of the invention is to provide a method of manufacturing such an improved tubular element.
A specific object of the invention is to provide an improved technique for reliable fastening of the sealing means on the tubular body.
These and other objects, which will appear from the following, have now been achieved by a tubular element for use in a fluid-conducting duct system, in particular a ventilation duct system, comprising an external, circumferential, flexible sealing ring mounted at an end of the tubular element, the sealing ring having a base which is clamped against the outer surface of the tubular element by means of the free end portion of the tubular element, which is bent radially outwards and turned back towards the wall of the tubular element, the sealing ring further having a sealing lip extending substantially radially away from said base and adapted to seal against an inner surface of an outer tube, in which the tubular element is inserted, the base of the sealing ring being disposed in a circumferential groove, which is formed in the wall of the tubular element and which has an axial width matching the axial width of said base, the sealing ring having a further lip or projection which is positioned adjacent to the end of the tube element and which is axially spaced from the sealing lip, said further lip extending substantially radially away from said base before said bending of the end portion of the tubular element, and said further lip being bent down and clamped against said base by means of said end portion by said bending.
The objects have also been achieved by a method of manufacturing a tubular element for use in a fluid-conducting duct system, in particular a ventilation duct system; in which an external, circumferential, flexible sealing ring is applied to the outer surface of a tubular body, said sealing ring having a base and a sealing lip extending substantially radially away therefrom; and in which the sealing ring is fastened to the tubular body by bending the free end portion of the tubular body radially outwards and backwards towards the wall of the tubular body, thereby clamping the base of the sealing ring between said bent end portion and said outer surface of the tubular body, the method comprising the steps that a circumferential groove is formed in the wall of the tubular body, said end portion of the tubular body being first bent to form a radially extending flange; that the sealing ring is placed in said groove which matches the sealing ring base, the sealing ring having a further lip which extends substantially radially from said base and which in this position extends adjacent to and substantially in parallel with the radial flange; and that the flange is then bent further back towards the wall of the tubular body so that the further lip is bent down together with the flange and clamped against the sealing ring base.
Since the sealing ring of the invention is disposed in a groove, it is far more easy to fix the same before the fastening operation compared to the known sealing ring placed on a raised step. Should the sealing ring of the invention for some reason be placed inaccurately before the bending operation, that is partially outside the groove, this is easily remedied. The misplaced sealing ring is only to be somewhat rotated, whereby the sealing ring base automatically finds its way into the groove.
The sealing ring base is disposed in the groove between defined shoulders of the same, which means that the sealing ring is safely kept in place during the fastening operation.
Thanks to the placement of the sealing ring base in the groove as well as the presence of the further lip, the improved sealing ring has no tendency to “tilt” as has been the case with known sealing rings. The design of the further lip as well as its connection to the sealing ring base further promote this advantage.
Since the further lip is bent down and firmly clamped against the sealing rig base by means of the end portion of the tubular element, a very reliable fastening of the sealing ring is achieved.
The base of the new sealing ring has no bulge, which makes the ring
Andersson Pontus
Lennartsson Kenneth
Mattssön Lars-Åke
Persson Tomas
Browne Lynne H.
Dunwoody Aaron
Lindab AB
Weingarten, Schurgin Gagnebin & Hayes LLP
LandOfFree
Tubular element with sealing means and a method for... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Tubular element with sealing means and a method for..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Tubular element with sealing means and a method for... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2439679