Exhaust pipe joint with insert

A connection assembly for pipes is provided. The assembly includes a pipe, a corrugated conduit, a circumferentially contractible seal positioned between portions of the conduit and the pipe, a clamp encircling the conduit, seal and pipe, and a plurality of discrete projections on the inside of the seal to limit the extent of overlap between the pipe and the conduit. The seal is circumferentially contractible to secure the conduit and the pipe together with the seal serving to effect a gas-tight seal while filling the annular gap between the conduit and pipe.

BACKGROUND OF THE INVENTION

The present invention generally relates to the field of pipe assemblies such as those used in vehicular exhaust systems and more particularly to an assembly having corrugated conduits that are clamped onto rigid piping and utilize a metal seal element to provide a fluid-tight connection therebetween. The present invention further provides a system that minimizes possible damage to the corrugations of the conduit.

Conduit and piping systems for conveying fluids and bulk materials are used in a wide variety of applications. Various components for such systems have been devised to accommodate different fluids and materials and to operate in particular environments. For example, some of the components of such systems are fabricated from flexible metal hose, which offers the advantages of durability, flexibility, relatively low cost and adaptability to various sizes, configurations and materials.

Flexible metal hose has been used for many years to interconnect components which move relative to each other. Some of the common configurations of flexible metal hose include spiral-wound, edge-interlocked hose wherein the edges of a strip of sheet metal are interlocked on a hose winding machine to permit limited deflection of the resulting flexible metal hose.

Corrugated flexible metal hose is another type of hose that can be, used. The corrugations provide flexibility and permit a corrugated pipe or hose section to be bent and shaped more easily than a comparable hose section with smooth walls. Moreover, corrugations can dissipate dynamic stresses associated with the vibration of the components to which the flexible hose section is attached.

Corrugated flexible hose sections can have corrugations of different diameters, such as bellows-type arrangement with the largest-diameter corrugations in the center and corrugations of decreasing diameters toward the ends whereby maximum flexibility is achieved in the center with increasing stiffness toward the ends (see U.S. Pat. No. 5,769,463 to Thomas). Such bellows-type configurations tend to be relatively efficient at dissipating vibrational energy toward their centers.

Hybrid flexible metal hose sections have also been fabricated from corrugated sheet metal bands which are spiral wound with their edges interlocked. The resulting hose sections can provide the advantages of both interlocked-edge and corrugated types of flexible metal hose types. For example, see Thomas U.S. Pat. No. 5,494,319.

Exhaust systems for internal combustion engines are examples of relatively severe environments in which the operating characteristics of flexible metal hoses can be used to advantage. Flexible metal hose sections are often used for connecting exhaust pipes from vehicle internal combustion engines with manifold mufflers, tail pipes and other exhaust system components. Flexible metal hose sections are commonly used in exhaust systems of tractors of tractor-trailer truck rigs and off road and construction vehicles because of their flexibility, temperature resistance and corrosion resistance when fabricated from suitable materials, such as stainless steel, galvanized steel or other metals.

Exhaust systems in general and vehicle exhaust systems in particular must perform reliably under relatively severe operating conditions, which can include temperature extremes, corrosive environmental factors and dynamic stress loading. Dynamic stresses in an exhaust system can originate from vibrations associated with the engine and movement of the vehicle. Such dynamic stresses include axial, lateral and angular forces, all of which can normally be effectively attenuated and controlled by flexible metal hose with corrugations and/or edge interlocking. However, torsional forces caused by the differential rotation of the exhaust system components connected by a flexible metal hose section can inflict significant damage, particularly when the flexible hose section ends are fixedly secured and the flexible section design is rigid with respect to rotational forces. Such dynamic torsional forces can lead to premature metal fatigue, cracking and failure of exhaust system components, including previous designs of flexible metal hose.

Pending U.S. patent application Ser. No. 10/718,785 filed by Thomas on Nov. 21, 2003 and published on May 27, 2004 discloses a system that effectively addresses the problem of dynamic torsional forces. Mating corrugations on corrugated conduits interfit so that the conduits can rotate relative to one another while maintaining a seal. While this system has worked well, it is not wholly without problems.

Notably, the corrugated pipe has an inside diameter greater than the outside diameter of the upstream pipe to which it is connected. A pipe clamp can be tightened on this joint to connect the piping components. However, the corrugated pipe is crushed and crumpled in the process because of its initially loose fit, thus leading to leakage at this joint. This is a serious problem and even more serious in the case of a system of the type shown in the pending Thomas application because crushing of the corrugated pipe can result in deformation extending to the corrugations. If that happens, the corrugations can be damaged to the point where relative rotation of the corrugated pipes is impeded or prevented altogether, thus resulting in failure of the system.

Another problem is that the clamp can slide on the pipe and possibly bang into and damage the corrugations as the clamp is being applied. This damage can lead to the same unacceptable result.

SUMMARY OF THE INVENTION

In the practice of the present invention, a metal conduit assembly is provided which includes a corrugated conduit section, at least one mating pipe, a clamp, and a seal element. The clamp incorporates a constriction means to releasably join the corrugated conduit, seal and mating pipe in a clamped relationship. The seal may be a split band having adjacent free ends or a band having slots arranged in a stair-step pattern. The ends of a split band seal are drawn together when the seal is constricted by the clamping action. The corrugated conduit may include a smooth neck portion with outwardly extending nodules or clamp stops to limit the axial movement of the clamp along the corrugated conduit. This prevents the clamp from engaging and possibly damaging the corrugations.

Other embodiments can be constructed to exhibit additional improved characteristics.

The seal can have one or more internal dimples to limit insertion of the exhaust pipe to a point where it cannot damage the corrugations. The corrugated or strip-wound pipe can be provided with a flared sleeve having an end extension which extends into the pipe to transfer vibrational forces away from the weld joint connecting the sleeve to the corrugated or strip-wound pipe.

The transition flare of the sleeve can serve as a stop to limit insertion of the other pipe to a point short of the corrugations. A flared sleeve can also be applied over the end of the corrugated or strip-wound pipe with the flare allowing variable insertion depths.

Other features and advantages of the invention will become apparent to those skilled in the art upon review of the following detailed description and drawings.

DETAILED DESCRIPTION OF THE INVENTION

Detailed embodiments of the present invention are described herein with reference to the Figures. The specific structural and functional details disclosed herein are intended to be exemplary and should not be interpreted as limiting the invention.

Referring to the drawings in detail, and initially toFIG. 1, the reference number10generally designates a pipe assembly constructed in accordance with one embodiment of coupling the present invention. The assembly10comprises a pair of corrugated conduits12and13, a pipe14, seal element16, and a clamp18, each having a generally circular transverse cross-sectional configuration.

The conduit12has a free end20and a series of corrugations29spaced from end20. The conduit12further comprises a bore22to accommodate flow of fluid or gases, e.g., vehicular exhaust gases. Located adjacent to the end20is a smooth-walled neck portion24of conduit12.

The conduit12has a generally circular transverse cross-sectional configuration, with the neck extension portion24having a smooth and generally cylindrical surface between end20and the corrugations29. The neck extension24has an inside diameter identified by numeral28inFIG. 2. The neck extension24provides a region for clamping conduit12onto pipe14.

The pipe14is cylindrical and has an outside diameter54at an open end15of the pipe.

The pipe14is adapted to be received within the open end20of the conduit12. In the illustrated embodiment, the outside diameter54of pipe14is smaller than the inside diameter28of conduit12. Thus, there is a small gap between the outside of pipe14and the inside of conduit12, as is the case when industry standard pipes are used.

The second corrugated conduit13is connected with the conduit12by means of interfitting corrugations that provide a mechanical connection while allowing relative rotation between the conduits12and13. As best shown inFIG. 6, conduit13has one or more corrugations31that fit closely inside of the corrugations29of conduit12in a manner described more fully in pending application Ser. No. 10/718,785 filed by Thomas on Nov. 21, 2003 and published on May 27, 2004. The interfitting corrugations29and31can rotate relative to one another to accommodate dynamic torsion forces that may be applied to the pipe assembly10in service. In order to maintain the integrity of this torsional joint, it is important that the corrugations not be deformed.

The seal16may take the form of a cylindrical band46having circular edges48A,48B (seeFIGS. 4 and 5). The seal16has a generally circular transverse cross-sectional or ring configuration with an outside diameter50. The seal16is adapted to fit on the pipe14and be received within the neck24.

As shown inFIG. 4, the seal element16may take the form of a split collar having free ends52F and52M that oppose one another. Ends52F and52M are V-shaped, with end52M having a male V-shape and end52F having a female V-shape generally matching end52M. A gap or slot54A is formed between ends52F and52M when the seal16is undeformed. The seal16may be constructed of a suitable metal able to withstand hot exhaust gases.

The included angle M identified inFIG. 4for the V angle of the male end52M may be approximately 100°, although various angles are possible. The gap54A may be more pronounced near the center where the vertices of the V-shapes are located than at the ends of the legs of the V-shapes. This allows the legs of the V-shape on the female end52F to spring outwardly and the vertices of the V-shapes to close on one another when the seal element16is compressed.

FIG. 5shows an alternative embodiment of a seal element generally identified by numeral116. The seal element116may be constructed in the same manner as seal element16except that element116has free ends52B that are straight edges spaced apart and parallel to one another to present a uniform gap or slot54B between them when the seal116is undeformed. The ends52B are angled relative to a plane extending transversely through the seal element. This angle is identified as angle A inFIG. 5and may be approximately 30-35°, although other angles are possible.

The connection between conduit12and pipe14is implemented by the clamp18.FIG. 3illustrates an exemplary assembly of components in the present invention, including the placement and juxtaposition of components. The body of clamp18is an annular band34. A pair of ears44are preferably integral with and extend from the band34and are each provided with an aperture40for receiving a suitable mechanical fastener such as a bolt and nut (not shown) which may be tightened to draw the ears44together and thus clamp neck24around the end portion of pipe14. The seal element16(or116) is sandwiched between pipe14and conduit12and is thus compressed when clamp18is tightened, thereby forming an effective seal and preventing conduit12from being crushed or crinkled significantly.

The seal16(or116) is located within the interior of the neck24of the conduit12. The pipe14is received within the seal16(or116). The seal16(or116) thus substantially fills in the area or the gap between the diameters28and54. Thus, a secure and gas-tight connection is formed therebetween, with the clamp providing a secure mechanical connection and the seal element providing an effective seal. When the clamp18is tightened, the free ends of the seal element are drawn together as the seal is compressed by the clamping force, without substantial deformation of the conduit12. The presence of the seal16(or116) provides a secure mechanical connection without crimping, crushing or crinkling of the corrugated conduit12in a manner that could deform the corrugations and disable the torsion joint between conduits12and13.

In the embodiment shown inFIG. 4, upon circumferential contraction of the seal16, the end portions60of the female end52F are expanded outwardly by contact with the end portions61of the male end52M to maintain effective sealing engagement. The seal116shown inFIG. 5, utilizes beveled ends52B that can close and then slide along one another to maintain effective sealing engagement. Small gaps may remain at the ends of the seal element and still provide an effective seal. The use of the seal16can accommodate for out of round or out of dimension or tolerance pipes14and necks24.

As previously described, the clamp18is located around the neck24of the coupler12. During the positioning of the clamp18, there is the potential that the clamp may be moved too far inwardly from the end20of the neck24, in the direction of the corrugations29. Placement of the clamp18too far inward on the neck24of the coupler12may result in the clamp damaging or deforming the corrugations29and thus compromising the integrity of the joint. To address this issue, the present invention provides a stop which may take the form of two or more nodular protrusions32located on the neck portion24of conduit12. The protrusions32are preferably located approximately 180 degrees apart and at a sufficient distance from end20of the neck24to allow axial adjustment of the clamp18along the neck24but preventing travel of the clamp18against the corrugations29. The protrusions32thus serve as a stop located between the conduit end20and the corrugations29.

The pipe assembly10of the present invention may be employed in a variety of applications where it is desirable to have couplings that can be taken apart and put back together with fluid tight seal maintained. In other words, the present invention is advantageous in an environment where a permanently formed coupling such as a welded joint would not provide the needed flexibility for replacement or reassembly of parts. An example of such an environment is a vehicle and in particular, truck, bus or heavy equipment exhaust systems.

FIGS. 7 and 8depict an alternative embodiment of the invention. This embodiment includes a corrugated conduit212having corrugations229that may mate with the corrugations of another corrugated pipe (not shown) to provide a rotational joint wherein the corrugations provide for relative rotation between the corrugated pipes. The corrugated pipe212has a smooth cylindrical neck224having a free end220. A bore222is formed in the conduit212to accommodate the flow of exhaust gases or other fluids. One or more beads or protrusions232are formed on the outside surface of the neck224. There are preferably two of the protrusions232formed at diametrically opposed locations on the neck224.

The embodiment ofFIGS. 7 and 8also includes a cylindrical pipe214having an outside diameter slightly smaller than the inside diameter of the neck224. The pipe214terminates in a circular end215.

A seal element216may take the form of a cylindrical band having a size to fit closely over pipe214and inside of the neck224. The seal element216may be a split band of the type shown inFIG. 4orFIG. 5, or it may be constructed otherwise to contract circumferentially when subjected to compressive force. By way of example, the seal element216may be provided in one of its edges with one or more pairs of stair-step slots generally identified by numeral270. The slots270may be of the type shown in U.S. Pat. No. 4,629,226 to Cassel et al., which is incorporated by reference with respect to the description of the stair-step slots270. The slots270include an inboard slot272and an outboard slot274. The slots272and274are offset circumferentially and axially on the seal element216, with corners of the two slots272and274being adjacent to one another. The seal element216is also provided with one or more internal dimples273. The dimples273are located near the edge of seal element216away from the slots270. There are preferably two dimples273at diametrically opposed locations on the seal element216.

A clamp218is used to implement the connection between conduit212and pipe214. The body of the clamp218may take the form of a split annular band234having a pair of ears244on opposite sides of the split. Apertures240are formed in the ears244in alignment with one another to receive a fastener (not shown) that may be used to draw the ears244together and thus contract the clamping band234.

The pipe assembly is shown inFIG. 8in its assembled condition. The seal element216is placed around the pipe214adjacent to the end215. The dimples273provide stops that properly locate the seal element216on pipe214and limit the insertion of the pipe214into the seal element and the corrugated conduit212. The pipe214and seal element216are then inserted inside of the neck224as shown inFIG. 8. The seal element216substantially fills the gap formed between the outside diameter of pipe214and the inside diameter of the conduit212. The final step in assembling the pipe assembly involves applying the clamp218to the neck224of the corrugated conduit and thus around the neck224, the seal element216and the end portion of pipe214. When the clamp218is tightened, the slots270allow the seal element216to circumferentially contract if necessary. The beads or protrusions232limit the movement of the clamp218onto neck224and thus prevent the clamp from moving far enough to contact and possibly damage the corrugations229.

FIG. 9depicts still another embodiment of the invention which includes a spiral wound conduit312, a pipe314, a flared sleeve316, and a clamp318. The spiral wound conduit312has an end320and presents an internal bore322for accommodating exhaust gases or other fluids. The conduit312may be constructed of spirally wound metal strips which interlock at their edges to provide corrugations329. The sleeve316has a cylindrical main body331, a cylindrical end extension332and a tapered transition section335which connects the body331with the end extension333. The body331has a larger diameter than the end extension330such that the transition section335tapers from the main body331to the end extension333. The end extension333has a diameter to fit closely inside of the corrugated conduit312and has a length to extend well into conduit312a substantial distance inwardly from the end320. The edge of the body331opposite the end extension333may be provided with one or more pairs of stair-step slots370which may be constructed similarly to slots270. A circular weld337is formed exteriorly around the end320of conduit312and the transition section335of sleeve316to provide a welded connection of sleeve316to conduit312.

The pipe314may be a smooth cylindrical pipe that terminates in a circular end315. The outside diameter of pipe314is preferably equal to or slightly less than the inside diameter of the main body331of sleeve316. Consequently, the end portion of pipe314can be inserted into the main body331. The insertion of pipe314is limited by engagement of its end315with the tapered transition section335of sleeve316.

The clamp318may be constructed in the same manner as clamps18and218. Ears344may be drawn together to tighten the clamp318upon tightening of a suitable fastener (not shown) inserted through aligned apertures340in the ears344.

The embodiment ofFIG. 9is assembled by placing the clamp318around sleeve316and inserting pipe314into sleeve316until end315is engaged with the stop provided by the transition section335. The clamp318can then be tightened to secure the conduit312and pipe314together. The presence of the slots370allows the body331of sleeve316to contract under the compression force applied by the clamp318to provide a secure and leak proof joint between conduit312and pipe314.

Because the end extension333extends well into the conduit312, vibration is transferred away from the weld337. Accordingly, the heat affected weld is protected from vibrations that could adversely effect the integrity of the weld.

FIG. 10depicts yet another embodiment of the invention which includes a corrugated or strip wound flexible conduit412, a pipe414, a sleeve416and a clamp418. The conduit412includes spirally wound strips having interlocked edges to present corrugations429. An edge420is formed on the end of the conduit412.

The sleeve416has a flared configuration and includes a cylindrical main body431, an enlarged cylindrical end433, and a tapered transition section435. The enlarged end section433is larger in diameter than the main body431such that the transition section435tapers from the end section433to the main body431. The enlarged end433has a diameter to fit closely around the end portion of conduit412and may be connected to the corrugated conduit by a circular weld437extending around the edge of the enlarged end433and around conduit412. A pair of stair-step slots470may be formed in the end portion of the main body431opposite the end section433.

The pipe414may be a smooth cylindrical pipe terminating in a circular edge415. The outside diameter of pipe414is preferably equal to or slightly smaller than the inside diameter of the main body431of sleeve416. Accordingly, pipe414can be inserted into the main body431. The clamp418is constructed in the same manner as clamp318and is provided with a pair of ears444having aligned apertures440. A fastener such as a bolt (not shown) may be extended through the apertures440and a nut may be tightened on the bolt to draw the ears444together, thus tightening the clamp418onto sleeve416. The slots470accommodate circumferential contraction of the main body431of sleeve416to assure a secure mechanical connection as well as a leak proof joint between the conduit412and pipe414.

The provision of an enlarged end433and the flared transition section435accommodate insertion of conduit412to variable depths within the sleeve416. Conduit412may be fully inserted to a point where its end420engages the transition section435to limit the depth of the insertion, and the weld437may then be effected to secure the sleeve416to conduit412. Alternatively, if necessary to accommodate the particular pipe installation, conduit412may be inserted only partially into the end section433such that the conduit end420is spaced from the transition section435when the weld437is made. Thus, if tolerance conditions or other variations are present, they can be accommodated by varying the insertion depth of conduit412into sleeve416as permitted by the enlarged end section, with a limit to the insertion depth provided by the transition section435.