Pipe joints or couplings – Materials – Sheet
Reexamination Certificate
1999-06-03
2001-03-13
Luu, Teri Pham (Department: 3627)
Pipe joints or couplings
Materials
Sheet
C285S382000, C285S420000
Reexamination Certificate
active
06199921
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to pipe couplings and, more particularly, to a pipe lap joint especially adapted for use in vehicle exhaust systems.
INVENTION BACKGROUND
In vehicle exhaust systems it is desirable for pipe joints to have high pull-apart strength and to provide a good fluid seal between the pipes. It is becoming increasingly important to provide exhaust pipe couplings that achieve greater reliability and uniformity in providing a good fluid seal.
In U.S. Pat. No. 4,629,226, granted Dec. 16, 1986 to Cassel, a pipe lap joint is disclosed which provides a collapsible sealing zone in the outer pipe. The sealing zone is formed by providing a pair of intersecting end-to-end slots in the outer pipe which provide relief for circumferential contraction of the sealing zone within an overlap region where the pipe ends overlap. A clamping band is disposed around the outside pipe and covers the inboard slot. When the clamping band is tightened around the outside pipe the sealing zone of the outer pipe is collapsed into close fitting engagement with the inner pipe. The intersecting outboard and inboard slots are circumferentially offset. Adjacent sidewalls of the slots are in substantial alignment with each other. The inner end wall of the outboard slot is in substantial alignment with the outer end wall of the inboard slot. With this alignment and with the sidewalls and end walls of the slots being rectilinear, an inner corner of the outboard slot makes a point-to-point intersection with an outer corner of the inboard slot. With this structure, only a very small amount of collapse of the outer pipe is necessary to cause a sealing engagement between the inner end wall of the outboard slot and the outer end wall of the inboard slot.
The Cassel et al. U.S. Pat. No. 5,588,680 discloses a pipe lap joint for vehicle exhaust system in which a pair of non-intersecting end-to-end slots are provided to afford relief for circumferential contraction of a sealing zone within an overlap region of two overlapped pipe ends. With this construction, precise location of the adjacent corners of the slots is required and the sidewalls and end walls that form the corners are rectilinear. In this pipe joint, a fluid seal is obtained upon tightening of the clamp on the outer pipe even though there is no substantial contraction of the sealing zone by collapse of the slots because a frangible bridging segment of the pipe wall extends between adjacent corners of the slots. Thus, the slots are isolated from each other when the frangible bridging element is either only slightly deformed or when it is completely fractured by collapse of the overlap region of the outer pipe.
A general object of this invention is to overcome certain disadvantages of the prior art and to provide a pipe lap joint with an improved sealing zone.
INVENTION SUMMARY
In accordance with this invention, a pipe lap joint is provided that exhibits good fluid sealing and pull-apart strength and that can be manufactured at low cost.
Further, in accordance with this invention, a pipe lap joint is provided in which an overlap region of an outside pipe over an inside pipe comprises a collapsible sealing zone with at least one slot extending from the end of the outer pipe to an inner end wall of the slot. The slot has an open end at the end of the outer pipe and terminates in a closed end within the overlap region of the pipe ends. The slot also has two generally parallel sidewalls that extend from the open end to the closed end, the closed end being defined by an end wall.
Further, in accordance with the invention, an integral bridge integrally extends from each sidewall and spans the slot adjacent the open end. The bridge is configured to collapse as the sidewalls of the slot move toward each other in response to the application of inward clamping pressure around the lap joint. The bridge collapses into a position that provides a fluid seal or sealing zone across the slot and between the inner and outer pipes.
Further in accordance with the invention, the bridge of the pipe wall is configured to seal off the slot by blocking axial fluid flow through the slot. The bridge seals off the slot whether or not the diametrical gap between the outer pipe and the inner pipe is large enough to require that the outer pipe be collapsed around the inner pipe to fit tightly around the inner pipe. In other words, a fluid seal is obtained upon tightening of the clamp on the outer pipe even though there is no contraction of the sealing zone by collapse of the slot because the bridge of the pipe wall extends across the slot adjacent the open end. Thus, the bridge isolates an axial inner portion of the slot from an outer portion of the slot whether or not the bridge is deformed at all by collapse of the overlap region of the outer pipe.
Still further in accordance with the invention, the bridge is configured so that the collapse of the outer pipe will not distort the bridge in such a way as to permit any significant leakage past or through the slot. This is because, for each embodiment, the bridge is configured to collapse without creating a gap between the bridge and the outer pipe
12
or between the bridge and the inner pipe
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. In other words, the bridge is a continuous unbroken structure from one sidewall to the other in both its collapsed and uncollapsed configuration.
REFERENCES:
patent: 4056273 (1977-11-01), Cassel
patent: 4113289 (1978-09-01), Wagner et al.
patent: 4629226 (1986-12-01), Cassel et al.
patent: 4660862 (1987-04-01), Cassel et al.
patent: 4753462 (1988-06-01), Liu
patent: 4902049 (1990-02-01), Umehara
patent: 5588680 (1996-12-01), Cassel et al.
patent: 5924282 (1999-07-01), Thomas
patent: 5944365 (1999-08-01), Kizler et al.
patent: 6089624 (2000-07-01), Cassel et al.
Amedure Michael E.
Cassel Scott T.
BKS Company LLC
Luu Teri Pham
Reising Ethington, Barnes, Kisselle, Learman & McCulloch, P.C.
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