Exhaust bellows for dynamic torsion control in an exhaust system

A flexible bellows tube connecting pipes in a system such as a vehicle exhaust system. Various embodiments are disclosed, with each including two conduit sections having mating corrugations that overlap to provide a seal while allowing the two sections to rotate in response to torsion loading. Different configurations of the interfitting corrugations and related structure are disclosed in the different embodiments.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to flexible hoses, and in particular to a flexible hose section which controls dynamic stresses in a system with components which are subjected to different dynamic forces.

2. Description of the Related Art

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 mental 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 towards 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 for dissipation.

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. Such hybrid hose designs can combine the advantages of both of these flexible metal hose types. For example, see the Thomas U.S. Pat. No. 5,494,319.

The disclosure of this patent, and also of the Thomas U.S. Pat. No. 5,882,046, are incorporated herein by reference.

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.

The present invention addresses these considerations in connection with the application of the flexible metal hose to applications involving dynamic stresses. Heretofore there has not been available a dynamic stress controlling flexible metal hose section with the advantages and features of the present invention.

SUMMARY OF THE INVENTION

In the practice of the present invention, a flexible hose section is provided which includes a body with a corrugated medial portion and first and second ends with first and second mouths. The body mouths receive the ends of upstream and downstream exhaust system pipe sections and are secured therein by suitable connectors, such as weldments, clamps, gaskets and the like. The hose section, through the arrangements of its corrugations and/or its end connections, permits relative rotational displacement between the exhaust pipe sections whereby dynamic torsional stress is attenuated in and controlled by the hose section. Alternative embodiments of the present invention include various arrangements of corrugations, end connections and multiple hose section body layers, which can include intermediate insulation layers and outer sleeves for greater dynamic stress control and heat resistance.

OBJECTS AND ADVANTAGES OF THE INVENTION

The principal objects and advantages of the present invention include providing a flexible hose section adapted to control dynamic stresses; providing such a hose section which is adapted to control axial, lateral, angular and rotational stresses; providing such a hose section which attenuates and dissipates forces associated with differential rotational forces in a system; providing such a hose section which dissipates heat; providing such a hose section which can be either rigidly or flexibly connected to other components in a system; providing such a hose section which can be fabricated from a variety of different materials; providing such a hose section which can operate effectively in relatively severe operating conditions, such as those associated with vehicle exhaust systems; providing such a hose section which is economical to manufacture, efficient in operation, capable of a long operating life and particularly well adapted for the proposed usage thereof.

DETAILED DESCRIPTION OF THE INVENTION

Detailed Description of the Preferred Embodiments

I. Introduction and Environment

Referring to the drawing in more detail, the reference numeral2generally designates an exhaust bellows for an exhaust system4embodying the present invention. The exhaust system4includes upstream and downstream exhaust pipe sections4a,bwith ends4c,dwhereat bores4e,fare open. The bellows2includes an upstream, inner section6with corrugations8including alternating lands8aand grooves8b. The inner section6has an upstream end10aadapted to be received within the upstream exhaust pipe section4aand a downstream end10b. A downstream, outer section12of the bellows2telescopically receives a downstream portion of the upstream, inner section6and includes a downstream end14bwith a bore16extending through the exhaust bellows. The downstream, outer section12includes corrugations18with alternating lands18aand grooves18b. The corrugations8,18of the inner and outer sections6,12overlie at a two-ply section20which is located adjacent to the outer section upstream end14aand extends through approximately two corrugation lands8a,18a. However, the two-ply section20could extend for a greater or lesser distance and can assume various configurations, as will be described in more detail below. A coating of lubricant22can be provided between the inner and outer sections6,12within the two-ply section20to facilitate relative movement (i.e., rotation) therebetween. The materials comprising the sections6,12can be chosen from a wide range of suitable materials chosen for corrosion resistance, strength, flexibility and ability to accommodate temperature changes. Price is also a factor in selecting the appropriate material. Examples include stainless steel number 304, 316, 321, 316TI (Titanium), 316L (low carbon) and various alloys.

The bellows2can be hydro-formed or mechanically formed to produce the corrugations8,18. The corrugated portions of the sections6,12are preferably tightly fit to provide an effective seal therebetween but the annular corrugated configurations thereof facilitate relative rotation therebetween in response to torsional stress loads on the bellows2. Such relative rotation can be further facilitated by utilizing a lubricant coating22therebetween, as described above. Still further, various liners and coatings, including high temperature plastics, metals or other materials could be located between the corrugations8,18.

FIG. 2 and 2ashow a bellows102comprising a first alternative embodiment of the present invention with a shortened inner section106terminating at a downstream end110blocated within the corrugated portion of the outer section112.

FIGS. 3 and 3ashow a bellows comprising a second alternative embodiment of the present invention. The bellows202includes a shortened inner section204terminating at a downstream end210band a corrugated section208located in proximity thereto. The corrugated section208includes an upstream, reduced-diameter corrugation208aand a downstream increase-diameter corrugation208b.

A downstream outer section212also includes a corrugated section218with reduced-diameter corrugations219corresponding to the inner section reduced-diameter corrugations209and enlarged-diameter corrugations221corresponding to the inner section enlarged-diameter corrugations211. The smaller-diameter corrugations209,219tend to be stiffer than the larger-diameter corrugations211,221and thus tend to transmit the vibrational forces towards the middle portion of the bellows212.

FIGS. 4 and 4ashow a bellows302comprising a third alternative embodiment of the present invention, with a construction similar to the bellows202described above except that an outer section312is provided with a corrugated section318with a single reduced-diameter corrugation319at an upstream end of the corrugated section318and enlarged-diameter corrugations321comprising the remainder of the corrugated section318.

FIGS. 5 and 5ashow a bellows402comprising a fourth alternative embodiment of the present invention. The bellows402includes inner and outer sections406,412respectively. The sections406,412include corresponding annular, outwardly-convex protrusions407and413respectively. The annular protrusions407,413closely overlie each other and provide an additional area of sealing contact between the inner and outer sections406,412.

A bellows502comprising a fifth alternative embodiment of the present invention is shown inFIGS. 6 and 6a. The bellows502includes inner and outer sections506,512respectively. The inner section506includes a pair of protrusions507similar to the protrusions described above. The outer section512also includes a pair of protrusions513, also similar to the protrusion413described above. The sections506and512also include reduced and enlarged-diameter corrugations509,511and519,521respectively, which are similar to those described above.

FIGS. 7 and 7ashow a bellows602comprising a sixth alternative embodiment of the present invention. The bellows602is similar to the bellows502described above, except that only single protrusions607,613are provided on an inner section606and an outer section612respectively.

FIGS. 8 and 8ashow a bellows702comprising a seventh alternative embodiment of the present invention. The bellows702includes an inner section706and an outer section712. The inner section706includes an annular projection707with an annular channel709formed therein. The outer section712includes an annular projection713which encloses the annular channel709to provide an internal raceway711which receives an annular packing ring715. The packing ring715can comprise a suitable material, such as fabric or metal, which can be adapted for high temperature applications and can provide additional packing against leakage.

The bellows802is similar to the bellows702described above, except that reduced-diameter corrugations809,819are provided in inner and outer sections806,812respectively.

FIGS. 10 and 10ashow a ninth alternative embodiment bellows902with inner and outer section906,912respectively. The inner section906is elongated and terminates at a downstream end910blocated just downstream of a corrugated length918of the outer section912. The inner and outer section906,912include reduced-diameter corrugations909,919respectively at the upstream end of the corrugated length918. Additionally, the outer section912includes a reduced-diameter corrugation919located at the downstream end of the corrugated length918.

FIGS. 11 and 11ashow a bellows1002comprising a tenth alternative embodiment of the present invention. The bellows1002includes an inner section1006and an outer section1012. The bellows1002is substantially similar to the bellows902, except that the outer section1012does not include a reduced-diameter corrugation1019at its downstream end, but does include such a corrugation at its upstream end which cooperates with and overlies a reduced-diameter corrugation of the inner section1006.

FIGS. 12 and 12ashow a bellows1102comprising an eleventh alternative embodiment of the present invention. The bellows1102is similar to the bellows402described above, except that an inner section1106thereof is relatively long and extends for substantially the entire length of a corrugated length1118of the outer section1112.

A bellows1202comprising the eleventh alternative embodiment is shown inFIGS. 13 and 13a. The bellows1202is similar to the bellows502described above, except that the inner section1206thereof is elongated and terminates at a downstream end1210blocated just downstream of a corrugated length1218of an outer section1212.

FIGS. 14 and 14ashow a thirteenth alternative embodiment bellows1302including an inner section1306and an outer section1312. The bellows1302is similar to the bellows1202described above, except that the inner and outer sections1306,1312respectively include only single annular protrusions1307and1313respectively.

FIGS. 15 and 15ashow a bellows1402comprising a fourteenth alternative embodiment of the present invention. The bellows1402is similar to the bellows702described above, except that an inner section1406thereof is elongated with a downstream end1410blocated just downstream of a corrugated length1418of an outer section1412.

FIGS. 16 and 16ashow a bellows1502comprising a fifteenth alternative embodiment of the present invention. The bellows1502is similar to the bellows802described above except that an inner section1506thereof includes a downstream end1510located downstream from a corrugated length1518of an outer section1512.

FIGS. 17 and 17ashow a bellows1602comprising a sixteenth alternative embodiment of the present invention. The bellows1602is similar to the bellows1502described above, except that all of the corrugations1611and1621of inner and outer sections1606,1612respectively are of substantially uniform diameter.

FIGS. 18 and 18ashow a bellows1702comprising a seventeenth alternative embodiment of the present invention. The bellows1702includes an outer ply1704with generally cylindrical end sections1706,1708and a bellows section1710therebetween. The bellows section1710includes a tapered end1712.

An inner ply1714is positioned generally within the outer ply1704and includes generally cylindrical end sections1715,1716with an intermediate section extending therebetween and located generally within the outer ply bellows section. The inner ply intermediate section includes an extended cylindrical section1713and a tapered bellows end section1717generally conforming to the configuration of the outer ply1704. A rigid sealing ring1718is mounted on one end of the inner ply1714. The opposite end of the outer ply1704receives another rigid sealing ring1720. The rings may be applied to both ends, neither end, or one of the ends of the assembly as desired.

The inner ply bellows section can be conformed to the configuration of the outer ply bellows section by means of a hydroforming or mechanical manufacturing process performed with or without a layer of lubricant between the plies. The tapered bellows portion of the inner ply can extend for any desired length and include any desired number of corrugations within the outer ply bellows section.

The inner and outer plies1704,1712can comprise any suitable material. For example, dissimilar materials can be used to avoid a galling interaction which can occur with two similar metals. Examples of suitable metals include stainless steel alloys designated 316, 316TI (Titanium), 316L (low carbon), 321 and 304. The stainless steel alloys with high number designations generally provide greater corrosion resistance, whereas lower numbers tend to be less expensive. Metals chosen for the inner and out ply constructions can have suitable properties of resistance to galvanic action.

FIGS. 19 and 19ashow a bellows1802comprising an eighteenth alternative embodiment of the present invention. The bellows1802is similar to the bellows1702described above, with a multiple ply material comprising the inner ply and/or the outer ply. As discussed above, the materials, proportions and dimensions of the bellows can vary considerably within the scope of the present invention.

FIGS. 20 and 20ashow a bellows2002comprising a nineteenth alternative embodiment of the present invention. The bellows2002includes an outer ply2012with corrugated, tapered bellows sections at both ends. First and second inner plies2006extend partway into the outer ply bellows section2012and terminate at inner ply ends which are positioned in spaced-apart relation.

In operation, the tapered bellows at both ends facilitate damping dynamic stresses. By providing a gap between the inner ply sections, torsional stress control is enhanced by facilitating slippage between the independent inner plies and outer ply. Still further, by providing connections between the inner and outer plies which are substantially fluid-tight, leakage can be controlled or at least greatly reduced. The end sections receive rings2020similar to rings1720.

FIGS. 21 and 21ashow a bellows2102comprising a twentieth alternative embodiment of the present invention. The bellows2102is similar to the bellows2002described above, except that the inner ply sections extend considerably further into the outer ply. Moreover, the inner ply sections terminate at ends2106awhich are only slightly spaced from each other. Rings2120are on the outer ends of the inner ply section2106. Operationally, the bellows2102functions in a manner similar to the bellows2002described above, with a few operational differences resulting from the extended end sections. For example, extended portions of the extended ply section resist deflection by the extended lengths of inner ply captured within the outer ply.

FIGS. 22 and 22Ashow a bellows2202comprising a twenty-first alternative embodiment of the present invention. The bellows2202is essentially identical to the bellows2shown inFIGS. 1 and 1a, except that the inner ply2206and the outer ply2212overlap at only a single corrugation identified at2207inFIG. 22a.

FIGS. 23 and 23ashow a bellows2302comprising a twenty-second alternative embodiment of the present invention. The bellows2302includes an outer ply2312with generally cylindrical end sections2312aand2312band an intermediate corrugated bellows section located therebetween. An inner ply2306is located generally within one end of the outer ply2312and includes a single corrugation2307which closely matches the configuration of the corresponding outer ply corrugation. The inner ply terminates at an inner end2306alocated within the outer ply bellows section2312and an outer free end2306b.

FIGS. 24 and 24ashow a bellows2402comprising a twenty-third alternative embodiment of the present invention. The bellows2402is similar to the bellows2302described above, with the addition of an intermediate ply2405comprising a layer of brass or some other suitable material located between the outer and inner plies,2412and2406, respectively. The material of the intermediate ply2405is preferably chosen for inertness and lack of interaction with the materials (generally metal) comprising the outer and inner plies. The intermediate ply2405extends generally from a first end2412aof the outer ply downstream to a location immediately downstream of the first corrugation2407. The intermediate ply2405facilitates the “slip plane” effect by maintaining a relative low coefficient of friction between the outer and inner plies whereby the aforementioned torsional loads can effectively be resisted throughout the life of the bellows. The intermediate ply2405can extend for any desired length between the outer and inner plies, and can be adapted to any configuration thereof, including, but not limited to, the outer/inner ply configurations described herein. In theFIG. 24embodiment, only a single corrugation2407overlaps between the inner and outer plies and the intermediate ply2405.

FIG. 25shows a bellows2502comprising a twenty-fourth alternative embodiment of the present invention. The bellows2502includes first and second bellows sections2502aand2502beach having inner and outer bellows section ends2550and2552, respectively. The outer section bellows ends include four regularly-spaced slots2554which facilitate constricting the diameters of the bellows outer sections when mounting same on an exhaust system component.

An interlock2556comprising helical windings has first (upstream) and second (downstream) ends2556aand2556b,respectively, received in bellows section inboard ends2550. First and second rings2558and2560are mounted in overlying relation over the bellows section ends2550and the interlocking section ends2556aand2556b.The rings2558and2560are secured in place by any suitable means, including clamping, adhesives and welding. For example, the rings can be seam welded, spot welded, TIG welded, etc.

FIG. 26shows a bellows2602comprising a twenty-fifth alternative embodiment of the invention. The bellows2602is similar to bellows2502except that bellows2602includes only a single bellows section2602awhich is relatively long and includes an inner ply2606and an interlocking yet relatively rotatable outer ply2612. An interlock2656comprising spiral workings has its upstream end received in the downstream end of the bellows section2602a. A ring2660is mounted to extend around the overlapping ends of section2602aand the interlock2656and can be secured in place by any suitable means.

Preferably the construction of the multi-ply bellows facilitates slippage between the plies by forming a “slip plane” therebetween. The effectiveness of the slip plane can be enhanced by lowering the coefficient of friction between the plies, and by minimizing interactions between the materials over the course of time which would otherwise cause them to bond with each other. In addition to choice of ply materials, various lubricants can be applied between the plies to minimize frictional engagement therebetween. Such lubricants include graphite pastes, liquid lubricants, spray-on lubricants, Boron Nitride and Microblue lubricant.

In operation the hydroformed or mechanically formed inner ply facilitates a tight-fitting engagement with the outer ply for sealing and minimizing or eliminating leakage, with the seal between the inner and outer plies being maintained during relative rotation between them. Torsional loads between the exhaust system components are thereby resisted through the relative slippage between the plies. Moreover, the function of the bellows is to accommodate displacement between the exhaust system components particularly in the form of axial loads tending to expand and compress the bellows. Other loads include displacements along the axes of the exhaust system components, which can be accommodated by the bellows sections and by the slip planes. The end rings1718and1720add to the stiffness of the end sections of the construction.

Embodiments that include an extended liner result in a relatively smooth bore which has a number of advantages, including noise reduction and a reduction in static losses.