Abstract:
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.

Description:
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. 
    
    
     
       BRIEF DESCRIPTION OF SEVERAL VIEWS OF THE DRAWINGS 
       The present invention is further described with reference to the accompanying drawings, which show various constructions and implementations of the present invention. However, it should be noted that the invention as disclosed in the accompanying drawings is for illustrative purposes only. The various elements and combinations of elements described below and illustrated in the drawings can be arranged and organized differently to result in constructions which are still within the spirit and scope of the present invention. The accompanying drawings form a part of the specification and are to be read in conjunction therewith, and like reference numerals are used to indicate like parts in the various views: 
         FIG. 1  is an exploded elevational view of a pipe assembly constructed according to one embodiment of the present invention; 
         FIG. 2  is an exploded perspective view of the pipe and corrugated conduit shown in  FIG. 1 ; 
         FIG. 3  is a sectional view of the pipe assembly shown in  FIG. 1 , illustrating the arrangement of the components; 
         FIG. 4  is a perspective view of a first embodiment of a seal constructed in accordance with the present invention, wherein the seal has substantially V-shaped ends; 
         FIG. 5  is a perspective view of a second embodiment of a seal, with the seal in this embodiment having angled beveled ends; 
         FIG. 6  is an enlarged sectional view of the detail identified by numeral  6  in  FIG. 1 ; and 
         FIG. 7  is an exploded side elevational view of a pipe assembly constructed according to another embodiment of the invention; 
         FIG. 8  is a side elevational view of the pipe assembly shown in  FIG. 7  in the assembled condition; 
         FIG. 9  is a fragmentary side elevational view of the components of a pipe assembly constructed according to still another embodiment of the invention; and 
         FIG. 10  is a fragmentary side elevational view of the components of a pipe assembly constructed according to yet another embodiment of the invention. 
     
    
    
     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 to  FIG. 1 , the reference number  10  generally designates a pipe assembly constructed in accordance with one embodiment of coupling the present invention. The assembly  10  comprises a pair of corrugated conduits  12  and  13 , a pipe  14 , seal element  16 , and a clamp  18 , each having a generally circular transverse cross-sectional configuration. 
     The conduit  12  has a free end  20  and a series of corrugations  29  spaced from end  20 . The conduit  12  further comprises a bore  22  to accommodate flow of fluid or gases, e.g., vehicular exhaust gases. Located adjacent to the end  20  is a smooth-walled neck portion  24  of conduit  12 . 
     The conduit  12  has a generally circular transverse cross-sectional configuration, with the neck extension portion  24  having a smooth and generally cylindrical surface between end  20  and the corrugations  29 . The neck extension  24  has an inside diameter identified by numeral  28  in  FIG. 2 . The neck extension  24  provides a region for clamping conduit  12  onto pipe  14 . 
     The pipe  14  is cylindrical and has an outside diameter  54  at an open end  15  of the pipe. 
     The pipe  14  is adapted to be received within the open end  20  of the conduit  12 . In the illustrated embodiment, the outside diameter  54  of pipe  14  is smaller than the inside diameter  28  of conduit  12 . Thus, there is a small gap between the outside of pipe  14  and the inside of conduit  12 , as is the case when industry standard pipes are used. 
     The second corrugated conduit  13  is connected with the conduit  12  by means of interfitting corrugations that provide a mechanical connection while allowing relative rotation between the conduits  12  and  13 . As best shown in  FIG. 6 , conduit  13  has one or more corrugations  31  that fit closely inside of the corrugations  29  of conduit  12  in 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 corrugations  29  and  31  can rotate relative to one another to accommodate dynamic torsion forces that may be applied to the pipe assembly  10  in service. In order to maintain the integrity of this torsional joint, it is important that the corrugations not be deformed. 
     The seal  16  may take the form of a cylindrical band  46  having circular edges  48 A,  48 B (see  FIGS. 4 and 5 ). The seal  16  has a generally circular transverse cross-sectional or ring configuration with an outside diameter  50 . The seal  16  is adapted to fit on the pipe  14  and be received within the neck  24 . 
     As shown in  FIG. 4 , the seal element  16  may take the form of a split collar having free ends  52 F and  52 M that oppose one another. Ends  52 F and  52 M are V-shaped, with end  52 M having a male V-shape and end  52 F having a female V-shape generally matching end  52 M. A gap or slot  54 A is formed between ends  52 F and  52 M when the seal  16  is undeformed. The seal  16  may be constructed of a suitable metal able to withstand hot exhaust gases. 
     The included angle M identified in  FIG. 4  for the V angle of the male end  52 M may be approximately 100°, although various angles are possible. The gap  54 A 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 end  52 F to spring outwardly and the vertices of the V-shapes to close on one another when the seal element  16  is compressed. 
       FIG. 5  shows an alternative embodiment of a seal element generally identified by numeral  116 . The seal element  116  may be constructed in the same manner as seal element  16  except that element  116  has free ends  52 B that are straight edges spaced apart and parallel to one another to present a uniform gap or slot  54 B between them when the seal  116  is undeformed. The ends  52 B are angled relative to a plane extending transversely through the seal element. This angle is identified as angle A in  FIG. 5  and may be approximately 30-35°, although other angles are possible. 
     The connection between conduit  12  and pipe  14  is implemented by the clamp  18 .  FIG. 3  illustrates an exemplary assembly of components in the present invention, including the placement and juxtaposition of components. The body of clamp  18  is an annular band  34 . A pair of ears  44  are preferably integral with and extend from the band  34  and are each provided with an aperture  40  for receiving a suitable mechanical fastener such as a bolt and nut (not shown) which may be tightened to draw the ears  44  together and thus clamp neck  24  around the end portion of pipe  14 . The seal element  16  (or  116 ) is sandwiched between pipe  14  and conduit  12  and is thus compressed when clamp  18  is tightened, thereby forming an effective seal and preventing conduit  12  from being crushed or crinkled significantly. 
     The seal  16  (or  116 ) is located within the interior of the neck  24  of the conduit  12 . The pipe  14  is received within the seal  16  (or  116 ). The seal  16  (or  116 ) thus substantially fills in the area or the gap between the diameters  28  and  54 . 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 clamp  18  is 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 conduit  12 . The presence of the seal  16  (or  116 ) provides a secure mechanical connection without crimping, crushing or crinkling of the corrugated conduit  12  in a manner that could deform the corrugations and disable the torsion joint between conduits  12  and  13 . 
     In the embodiment shown in  FIG. 4 , upon circumferential contraction of the seal  16 , the end portions  60  of the female end  52 F are expanded outwardly by contact with the end portions  61  of the male end  52 M to maintain effective sealing engagement. The seal  116  shown in  FIG. 5 , utilizes beveled ends  52 B 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 seal  16  can accommodate for out of round or out of dimension or tolerance pipes  14  and necks  24 . 
     As previously described, the clamp  18  is located around the neck  24  of the coupler  12 . During the positioning of the clamp  18 , there is the potential that the clamp may be moved too far inwardly from the end  20  of the neck  24 , in the direction of the corrugations  29 . Placement of the clamp  18  too far inward on the neck  24  of the coupler  12  may result in the clamp damaging or deforming the corrugations  29  and 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 protrusions  32  located on the neck portion  24  of conduit  12 . The protrusions  32  are preferably located approximately 180 degrees apart and at a sufficient distance from end  20  of the neck  24  to allow axial adjustment of the clamp  18  along the neck  24  but preventing travel of the clamp  18  against the corrugations  29 . The protrusions  32  thus serve as a stop located between the conduit end  20  and the corrugations  29 . 
     The pipe assembly  10  of 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 8  depict an alternative embodiment of the invention. This embodiment includes a corrugated conduit  212  having corrugations  229  that 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 pipe  212  has a smooth cylindrical neck  224  having a free end  220 . A bore  222  is formed in the conduit  212  to accommodate the flow of exhaust gases or other fluids. One or more beads or protrusions  232  are formed on the outside surface of the neck  224 . There are preferably two of the protrusions  232  formed at diametrically opposed locations on the neck  224 . 
     The embodiment of  FIGS. 7 and 8  also includes a cylindrical pipe  214  having an outside diameter slightly smaller than the inside diameter of the neck  224 . The pipe  214  terminates in a circular end  215 . 
     A seal element  216  may take the form of a cylindrical band having a size to fit closely over pipe  214  and inside of the neck  224 . The seal element  216  may be a split band of the type shown in  FIG. 4  or  FIG. 5 , or it may be constructed otherwise to contract circumferentially when subjected to compressive force. By way of example, the seal element  216  may be provided in one of its edges with one or more pairs of stair-step slots generally identified by numeral  270 . The slots  270  may 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 slots  270 . The slots  270  include an inboard slot  272  and an outboard slot  274 . The slots  272  and  274  are offset circumferentially and axially on the seal element  216 , with corners of the two slots  272  and  274  being adjacent to one another. The seal element  216  is also provided with one or more internal dimples  273 . The dimples  273  are located near the edge of seal element  216  away from the slots  270 . There are preferably two dimples  273  at diametrically opposed locations on the seal element  216 . 
     A clamp  218  is used to implement the connection between conduit  212  and pipe  214 . The body of the clamp  218  may take the form of a split annular band  234  having a pair of ears  244  on opposite sides of the split. Apertures  240  are formed in the ears  244  in alignment with one another to receive a fastener (not shown) that may be used to draw the ears  244  together and thus contract the clamping band  234 . 
     The pipe assembly is shown in  FIG. 8  in its assembled condition. The seal element  216  is placed around the pipe  214  adjacent to the end  215 . The dimples  273  provide stops that properly locate the seal element  216  on pipe  214  and limit the insertion of the pipe  214  into the seal element and the corrugated conduit  212 . The pipe  214  and seal element  216  are then inserted inside of the neck  224  as shown in  FIG. 8 . The seal element  216  substantially fills the gap formed between the outside diameter of pipe  214  and the inside diameter of the conduit  212 . The final step in assembling the pipe assembly involves applying the clamp  218  to the neck  224  of the corrugated conduit and thus around the neck  224 , the seal element  216  and the end portion of pipe  214 . When the clamp  218  is tightened, the slots  270  allow the seal element  216  to circumferentially contract if necessary. The beads or protrusions  232  limit the movement of the clamp  218  onto neck  224  and thus prevent the clamp from moving far enough to contact and possibly damage the corrugations  229 . 
       FIG. 9  depicts still another embodiment of the invention which includes a spiral wound conduit  312 , a pipe  314 , a flared sleeve  316 , and a clamp  318 . The spiral wound conduit  312  has an end  320  and presents an internal bore  322  for accommodating exhaust gases or other fluids. The conduit  312  may be constructed of spirally wound metal strips which interlock at their edges to provide corrugations  329 . The sleeve  316  has a cylindrical main body  331 , a cylindrical end extension  332  and a tapered transition section  335  which connects the body  331  with the end extension  333 . The body  331  has a larger diameter than the end extension  330  such that the transition section  335  tapers from the main body  331  to the end extension  333 . The end extension  333  has a diameter to fit closely inside of the corrugated conduit  312  and has a length to extend well into conduit  312  a substantial distance inwardly from the end  320 . The edge of the body  331  opposite the end extension  333  may be provided with one or more pairs of stair-step slots  370  which may be constructed similarly to slots  270 . A circular weld  337  is formed exteriorly around the end  320  of conduit  312  and the transition section  335  of sleeve  316  to provide a welded connection of sleeve  316  to conduit  312 . 
     The pipe  314  may be a smooth cylindrical pipe that terminates in a circular end  315 . The outside diameter of pipe  314  is preferably equal to or slightly less than the inside diameter of the main body  331  of sleeve  316 . Consequently, the end portion of pipe  314  can be inserted into the main body  331 . The insertion of pipe  314  is limited by engagement of its end  315  with the tapered transition section  335  of sleeve  316 . 
     The clamp  318  may be constructed in the same manner as clamps  18  and  218 . Ears  344  may be drawn together to tighten the clamp  318  upon tightening of a suitable fastener (not shown) inserted through aligned apertures  340  in the ears  344 . 
     The embodiment of  FIG. 9  is assembled by placing the clamp  318  around sleeve  316  and inserting pipe  314  into sleeve  316  until end  315  is engaged with the stop provided by the transition section  335 . The clamp  318  can then be tightened to secure the conduit  312  and pipe  314  together. The presence of the slots  370  allows the body  331  of sleeve  316  to contract under the compression force applied by the clamp  318  to provide a secure and leak proof joint between conduit  312  and pipe  314 . 
     Because the end extension  333  extends well into the conduit  312 , vibration is transferred away from the weld  337 . Accordingly, the heat affected weld is protected from vibrations that could adversely effect the integrity of the weld. 
       FIG. 10  depicts yet another embodiment of the invention which includes a corrugated or strip wound flexible conduit  412 , a pipe  414 , a sleeve  416  and a clamp  418 . The conduit  412  includes spirally wound strips having interlocked edges to present corrugations  429 . An edge  420  is formed on the end of the conduit  412 . 
     The sleeve  416  has a flared configuration and includes a cylindrical main body  431 , an enlarged cylindrical end  433 , and a tapered transition section  435 . The enlarged end section  433  is larger in diameter than the main body  431  such that the transition section  435  tapers from the end section  433  to the main body  431 . The enlarged end  433  has a diameter to fit closely around the end portion of conduit  412  and may be connected to the corrugated conduit by a circular weld  437  extending around the edge of the enlarged end  433  and around conduit  412 . A pair of stair-step slots  470  may be formed in the end portion of the main body  431  opposite the end section  433 . 
     The pipe  414  may be a smooth cylindrical pipe terminating in a circular edge  415 . The outside diameter of pipe  414  is preferably equal to or slightly smaller than the inside diameter of the main body  431  of sleeve  416 . Accordingly, pipe  414  can be inserted into the main body  431 . The clamp  418  is constructed in the same manner as clamp  318  and is provided with a pair of ears  444  having aligned apertures  440 . A fastener such as a bolt (not shown) may be extended through the apertures  440  and a nut may be tightened on the bolt to draw the ears  444  together, thus tightening the clamp  418  onto sleeve  416 . The slots  470  accommodate circumferential contraction of the main body  431  of sleeve  416  to assure a secure mechanical connection as well as a leak proof joint between the conduit  412  and pipe  414 . 
     The provision of an enlarged end  433  and the flared transition section  435  accommodate insertion of conduit  412  to variable depths within the sleeve  416 . Conduit  412  may be fully inserted to a point where its end  420  engages the transition section  435  to limit the depth of the insertion, and the weld  437  may then be effected to secure the sleeve  416  to conduit  412 . Alternatively, if necessary to accommodate the particular pipe installation, conduit  412  may be inserted only partially into the end section  433  such that the conduit end  420  is spaced from the transition section  435  when the weld  437  is made. Thus, if tolerance conditions or other variations are present, they can be accommodated by varying the insertion depth of conduit  412  into sleeve  416  as permitted by the enlarged end section, with a limit to the insertion depth provided by the transition section  435 . 
     From the foregoing, it will be seen that this invention is one well adapted to attain all the ends and objects hereinabove set forth together with other advantages which are obvious and which are inherent to the structure. It will be understood that certain features and sub combinations are of utility and may be employed without reference to other features and sub combinations. This is contemplated by and is within the scope of the claims. Since many possible embodiments of the invention may be made without departing from the scope thereof, it is also to be understood that all matters herein set forth or shown in the accompanying drawings are to be interpreted as illustrative and not limiting. 
     The constructions described above and illustrated in the drawings are presented by way of example only and are not intended to limit the concepts and principles of the present invention. Thus, there has been shown and described several embodiments of a novel invention. As is evident from the foregoing description, certain aspects of the present invention are not limited by the particular details of the examples illustrated herein, and it is therefore contemplated that other modifications and applications, or equivalents thereof, will occur to those skilled in the art. The terms “having” and “including” and similar terms as used in the foregoing specification are used in the sense of “optional” or “may include” and not as “required”. Many changes, modifications, variations and other uses and applications of the present construction will, however, become apparent to those skilled in the art after considering the specification and the accompanying drawings. All such changes, modifications, variations and other uses and applications which do not depart from the spirit and scope of the invention are deemed to be covered by the invention which is limited only by the claims which follow.