GB2476294A

GB2476294A - Flange joint and gasket

Info

Publication number: GB2476294A
Application number: GB0922144A
Authority: GB
Inventors: Suresh Mistry
Original assignee: Federal Mogul LLC
Current assignee: Federal Mogul LLC
Priority date: 2009-12-18
Filing date: 2009-12-18
Publication date: 2011-06-22
Also published as: GB0922144D0

Abstract

A flange joint having a ridge 26 formed on a first flange 22 and a corresponding groove or channel 16 formed on a second flange 12 for receiving the ridge 26. A sealing member 30 having a generally U-shaped cross-section is seated in the groove 16 and has a base wall 37 including at least one base wall embossment 34 and at least one of its side walls 38, 39 includes at least one side wall embossment 36. The embossments 34, 36 are different in height or depth, or the height or depth of one of the embossments varies along its length. The groove 16 and ridge 26 may be non-circular or irregular in shape so as to provide more even thermal expansion and bolt load distribution across the flanges thereby further enhancing the sealing performance of the flange joint.

Description

FLANGE JOINT AND GASKET

The present invention relates to a flange joint and gasket and particularly, but not exclusively, to a flange joint and gasket for joining and sealing exhaust pipes and associated components of internal combustion engines. The invention provides advantageous application for joining an exhaust pipe to an intake manifold of a turbocharger or similar forced-induction device. Aspects of the invention relate to a joint, to an exhaust system, to a component for an exhaust system and to a vehicle.

Exhaust pipes of internal combustion engines generally consist of a plurality of pipe sections that are joined end to end by joints which are sealed to prevent the unwanted discharge of exhaust gases and the ingress of atmospheric air into the exhaust system. Frequently, each pipe section is provided with a flange face at a respective end thereof for engagement with a corresponding flange face on the adjacent pipe section. A seal, such as a gasket, is usually disposed between the flange faces to reduce or substantially prevent discharge of exhaust gases through the joint and the flange faces are tightly clamped together by means of bolts passing through corresponding fixing apertures in each flange face.

Sealing performance at such joints is of great importance to the performance of the internal combustion engine and the exhaust system. Exhaust systems in modern internal combustion engines must be designed for increasingly higher temperatures and longer operating periods.

Inadequate sealing can result in exhaust gases leaking from the joints upstream of the catalytic converter, increasing the level of pollutants emitted into the atmosphere.

Alternatively, or in addition, atmospheric air may enter the exhaust system, enriching the oxygen content of the exhaust gases. This increased oxygen content is measured by sensors downstream in the exhaust system and may be erroneously interpreted as the result of a weak fuel-air mixture in the internal combustion engine. The engine management system may therefore increase the fuel supply to the engine in order to enrich the fuel-air mixture. As a result, the efficiency of internal combustion engine is reduced and pollutant emissions are increased.

It is an aim of the present invention to address the above problems and to improve upon known technology. It is a further aim of the present invention to address problems associated with distortion and leakage from flange joints due to uneven load distribution and thermal expansion of the joint, as described below. Embodiments of the invention may provide a flanged joint and/or a gasket for a flanged joint which provides improved sealing performance in high temperature and pressure environments. Other aims and advantages of the invention will become apparent from the following description, claims and drawings.

Aspects of the invention therefore provide a joint, an exhaust pipe component, an exhaust system and a vehicle as claimed in the appended claims.

According to one aspect of the invention for which protection is sought there is provided a joint or connection for joining and sealing first and second pipes of an exhaust system, the joint comprising a first flange disposed at one end of the first pipe and a second flange disposed at one end of the second pipe, the first flange having a groove formed therein surrounding said first pipe and the second flange having a ridge formed thereon for insertion into and/or cooperation with the groove in the first flange.

In an embodiment, the groove disposed in the first flange and the ridge formed on the second flange are correspondingly shaped for sealing engagement therebetween. That is to say, the cross sectional shape and dimensions of the groove correspond to and are in proportion to those of the ridge such that a sealing ring is formed around the pipes.

In an embodiment, the joint or connection comprises clamping means for clamping the first and second flanges together. The clamping means may be arranged to clamp the first and second flanges with a defined clamping pressure. In an embodiment, the clamping means comprises at least one threaded member such as a screw or bolt.

In an embodiment, the joint comprises sealing means for sealing the engagement region of the groove and ridge. In an embodiment, the sealing means comprises a gasket arranged for seating in the groove.

The gasket may comprise a band of flexible and/or resilient material shaped to locate within the groove formed in the first flange. The gasket may be substantially V-shaped or U-shaped in cross-section so as to conform to the shape of the groove and define a slot for receiving the ridge formed on the second flange.

The gasket may comprise one or more crimps, folds, embossments or corrugations along its cross section. These features may improve the sealing performance of the joint by defining one or more sealing zones. Advantageously, the depth of the crimps, folds, embossments or corrugations may vary along the cross section of the gasket. Thus, in one embodiment, the gasket includes a first crimp having a first depth and a second crimp having a second depth, the first and second depths being different.

In one embodiment, a base wall of the gasket comprises a crimp or embossment having a first depth, and left and right side walls of the gasket each comprises a crimp or embossment having a second depth, the first and second depths being different. Such an arrangement advantageously provides a three-contact-point seal between the ridge and the groove, thereby improving sealing performance.

The or each crimp, fold or embossment may vary in height around the circumference of the gasket.

The gasket may be formed from a high temperature alloy. Advantageously, the gasket may be flexible and/or resilient. The gasket may be compressed or deformed when inserted into the groove so as to be self-retaining within the groove. The gasket may be inserted into the groove by means of a press fit or snap fit.

In one embodiment, the groove and ridge formed in the first and second flanges, respectively, are generally circular or ring-shaped. The gasket for such an embodiment may therefore be substantially annular in shape.

In another embodiment, however, the groove and ridge are non-circular. For example, the groove and ridge may be generally square, rectangular or triangular. In one embodiment, the groove and ridge are irregular in shape. Advantageously, the groove and ridge may be shaped so as maintain a more even thickness of material between the groove and the outer edge of the flange. Such an arrangement may improve bolt load distribution in the joint, as well as reducing distortion of the joint by more evenly controlling thermal expansion.

In one embodiment, each of the groove, ridge and gasket are generally triangular in shape having inverted vertices.

The joint or connection may comprise a joint between two pipes of an exhaust system or a joint between an exhaust manifold and an exhaust pipe, or a joint between an inlet or an outlet of a turbocharger or the like and another component.

According to another aspect of the invention for which protection is sought, there is provided an exhaust system having a joint or connection as set out in any of the preceding paragraphs.

According to a further aspect of the invention for which protection is sought, there is provided a vehicle having an exhaust system or a joint or connection as set out in any of the preceding paragraphs.

Within the scope of the present invention it is envisaged that the various aspects, embodiments, examples, features and alternatives set out in the preceding paragraphs, in the claims and/or in the following description and drawings may be taken independently or in any combination thereof.

The present invention will now be described, by way of example only, with reference to the accompanying drawings in which: Figure 1 illustrates a flanged joint embodying a first form of the invention; Figure 2 is a cross-section through the joint of Figure 1 showing insertion of a gasket into the groove; Figure 3 is a cross-section through the joint of Figure 1 with the gasket fully inserted in the groove and showing insertion of the ridge into the groove; Figure 4 is a cross-section through the joint of Figure 1 with the first and second flanges in substantially complete engagement; Figure 5 is an end view of a flange of a joint embodying one form of the invention; and Figure 6 is an end view of a flange of a joint embodying another form of the invention.

In the following description, as far as possible, like reference numerals indicate like parts.

Referring firstly to Figure 1, a flange joint embodying one form of the invention is shown, in disassembled form, generally at 10. The flange joint comprises a first flange 12, in the form of a generally elliptical plate, which is rigidly fixed to one end of a first pipe member (not shown) such as an exhaust pipe section or an inlet manifold of a turbocharger device or the like. The flange 12 has a circular aperture 14 formed therein which is sized and shaped to fit tightly around the circumference of the first pipe member where it is rigidly held in place by a weld.

A second flange 22, also taking the form of a generally elliptical shape corresponding to that of the first flange, is rigidly fixed to one end of a second pipe member (not shown). The second flange 22 also has a circular aperture 24 formed therein that is sized and shaped to fit tightly around the circumference of the second pipe member where it is rigidly held in place by a weld.

Of course the illustrated embodiment is only by way of example and in other embodiments the flanges may be provided as integral portions of cast components, such a manifold, a pipe end section or a turbine housing.

A generally circular channel or groove 16 is formed in the surface of first flange 12, concentric with and surrounding the aperture 14. The groove 16 is generally square or rectangular in cross section having a base surface 17 and opposing side surfaces 18, 19. In one embodiment (shown in Figure 2), the groove 16 is slightly tapered towards the base surface 17, the width of which is slightly less than the width of the groove at the surface of the first flange 12.

A correspondingly shaped projection or ridge 26 is formed on the surface of the second flange 22, again concentric with and surrounding the aperture 24. The ridge 26 is shaped to be received in the groove 16 and is thus generally square or rectangular in cross section having an upper surface 27 and opposing side surfaces 28, 29. As shown in Figure 4, however, the ridge 26 may be slightly tapered towards its upper surface 27, the width of which may therefore be slightly less than the width of the ridge at the surface of the second flange 22.

A sealing member, in the form of an annular gasket 30, is arranged to be seated in the groove 16. The gasket will be described in further detail below.

Both the first and second flanges 12, 22 include fixing holes 32, 34 through which suitable clamping means, such as screws or bolts (not shown) may be inserted so as to clamp the flanges together to form the flange joint.

Referring next to Figures 2-4, these illustrate steps in the assembly of a flange joint according to an embodiment of the present invention and show a cross section through the groove 16 (Figure 2) and ridge 26 (Figures 3 and 4) during mating of the flanges 12, 22.

Figure 3 also illustrates the cross-section of an advantageous form of gasket 30 for use with the flange joint of the present invention.

As shown in Figure 2, the gasket 30 has a generally U-shaped cross-section that broadly corresponds to the cross-section of the groove 16 and thus comprises a base wall 37 and opposing side walls 38, 39. One or more embossments, in the form of folds, crimps or corrugations 34, 36, are formed in the base wall 37 and side walls 38, 39 and extend continuously or discontinuously around the circumference of the gasket 30.

It can be seen that the height or depth of the embossment 34 formed in the base wall 37 is greater than that of the embossments 36 formed in the side walls 38, 39. For example, the embossment 34 may comprise a full embossment, while the embossments 36 may comprise half embossments. This is not essential, however, and the arrangement may be such that the embossment in the base wall 37 is shallower than those formed in the side walls 38, 39.

Alternatively, the embossments 34, 36 may have similar depths. A beneficial technical effect of having embossments of different depths is that it enables better load distribution around the sealing aperture governed by the load concentrations around the bolts. Around the bolts there is a greater load than in the regions between bolts. An increased pressure on the seal in the latter regions is advantageous to maintain an even sealing pressure throughout. The different height or depth embossments also helps in compensation for casting tolerance surface roughness.

In a first step of assembly of the flange joint (Figure 2), the gasket 30 is inserted into the around bolts you get more load. In the same spaces between you need more pressure on the seal, groove 16 in the first flange 12 such that its base wall 37 is in abutment with the base wall 17 of the groove 16 and its open face is directed outwardly. The internal angle between the side walls 38, 39 and the base wall 37 of the gasket 30 is greater than that between the side walls 18, 19 and base wall 17 of the groove 16 such that when the gasket is inserted into the groove 16, the side walls 38, 39 are compressed inwardly.

The elastic deformation of the side walls 38, 39 causes them to become resiliently biased into engagement with the side walls 18, 19 of the groove 16, thereby retaining the gasket 30 within the groove 16. This self-retaining of the gasket 30 within the groove 16 facilitates assembly by ensuring correct orientation in the groove and eliminating the need to hold the gasket 30 in place during mating of the flanges 12, 22.

In a second step (Figures 3 and 4) the second flange 22 is mated with the first flange 12 such that the ridge 26 enters the channel defined by the groove 16 and the gasket 30 seated therein. Both the groove 16 and the ridge 26 are tapered so as to facilitate insertion of the ridge 26 into the channel and to ensure correct alignment of the flanges and pipe members.

As shown in Figure 4, when the ridge 26 is fully inserted into the groove 16, the gasket 30 is deformed further and compressed into sealing engagement with the base and side walls of the groove 16 and the ridge 26. In particular, the illustrated arrangement advantageously provides at least three points of contact with the ridge 26 and the groove 16 (namely in the base wall 37 and each side wall 38, 39) thereby significantly improving the sealing performance. More than three points of contact are also possible and advantageous.

The deformation of the gasket 30 on full insertion of the ridge 26 into the groove 16 allows the flange joint to accommodate a range of tolerances and also any distortion of the flanges due to, for example, thermal expansion.

In a final step (not shown), the first and second flanges 12, 22 are clamped together using suitable fastening elements such as screws or bolts which pass through the fixing holes 32, 34. The clamping pressure exerted by the fastening elements further deforms the gasket so as to generate an effective seal in both radial and axial directions.

Referring next to Figure 5, this illustrates an axial view of an alternative form of flange. In this embodiment, the flange is generally triangular in shape having curved apices and features three fixing holes 44, each located at a respective vertex. As with the above-mentioned embodiments, the groove 16, ridge 26 and gasket 30 of the embodiment of Figure 5 are generally circular.

A problem with this type of arrangement is that the wall thickness of the flange varies significantly around the circumference of the groove. That is to say, the thickness of the flange wall at point A is greater than that at point B resulting in a non-uniform wall strength around the circumference of the flange. In particular, the reduced thickness portions of the flange wall are more susceptible to deformation due to thermal expansion or non-uniform distribution of the clamping force. This can result in flange distortion and reduced seal effectiveness.

The applicant has recognised, however, that, due to its channel-shaped form, the gasket described with reference to Figures 2-4 can be adapted to fit other shapes of grooves 16 in order to overcome the above problems. That is to say, it is possible to seal non-circular grooves 16 and ridges 26 in the flange joint by the use of this form of gasket.

Referring to Figure 5, for example, this illustrates a variation to the embodiment of Figure 4 wherein the groove 16 is substantially triangular in shape having inverted apices (vertices) to allow for the fixing holes 44. The groove 16 thus generally conforms to the external shape of the flange such that the wall thickness of the flange radially outwardly of the groove 16 is generally constant along much of the circumference thereof. That is to say, the thickness of the flange wall at points A, B and C are substantially equal.

This provides a number of benefits: a more uniform thermal expansion of the flange can be achieved due to the greater evenness of the flange wall thickness around the outside of the groove, thereby reducing heat-induced deformation or distortion of the flange. In addition, bolt load distribution within the flange joint may be improved, thereby improving sealing performance.

The shape of groove 16 and gasket 30 shown in Figure 5 is by way of example only and it is envisaged that substantially any shape may be employed, for example so as to correspond generally with the shape of the flange, in order to achieve favourable deformation and load distribution characteristics for the joint.

It will be appreciated by those skilled in the art that the gasket may be made of any suitable material, such as a high temperature alloy (HTA). It is advantageous, though not essential, that the material used to form the gasket is flexible and/or resilient to enable self-retention in the groove 16.

Manufacturing of the gasket 30 may be achieved, for example, by stamping the appropriate shape (circular, in the case of the embodiments of Figures 1 and 5, non-circular in the case of the embodiment of Figure 6) from a sheet of suitable material, such as a high temperature alloy or spring steel, and folding or turning the edges to form the base and side walls 37-39.

The embossments could be applied before or after stamping of the gasket 30 from a pre form blank. If they are formed after stamping, the embossments could be produced either before or after the final raising of the sides of the U-shape cross-section.

The gasket 30 may be single-or multi-layered, as desired. A multi-layered gasket may be capable of accommodating larger flange distortions.

The provision of embossments (used herein and in the claims to include, without limitation, protrusions, ridges, folds, crimps or corrugations) in the base and/or side walls 37-39 of the gasket 30 is not essential but, where present, the number of embossments may be selected as desired. For example, a single embossment 34 may be formed in the base wall 37 of the gasket 30 with no embossments formed in the side walls 38, 39. Alternatively, only the side walls 38, 39 of the gasket may be provided with embossments.

The or each embossment 34, 36 where present, may extend continuously or discontinuously around the circumference of the gasket 30 and its height (depth) may vary, or remain substantially constant along its length.

In an embodiment (not shown), the side walls 38, 39 of the gasket 30 are longer than the corresponding side walls 18, 19 of the groove such that, on insertion of the gasket into the groove, the side walls 38, 39 protrude therefrom. In this embodiment, insertion of the ridge 26 into the channel defined by the groove 16 and gasket 30 causes the free ends of the walls 38, 39 to be deformed outwardly by the face of the second flange. That is to say, the free ends of the side walls 38, 39 are bent outwardly through almost 90° so as to be clamped between the abutting surfaces of the flanges 12, 22. This advantageously increases the sealing area, particularly if the extended portions of the side walls 38, 39 are also provided with embossments.

The groove 16 may be formed in the first flange 12 during casting of the flange or may be machined into the flange surface after casting. The ridge 26 is preferably integrally formed with the second flange 22 and, again, may be formed during casting of the flange.

The present invention provides an improved form of flange joint having a so-called labyrinth formation comprising a ridge formed on a first flange and a corresponding groove or channel formed on a second flange for receiving the ridge. This interlocking of the ridge and groove increases the sealing surface area thereby improving sealing performance. Sealing performance is further improved by the provision of a sealing member in the groove.

The sealing member has a cross-section which enables it to be formed in a multitude of shapes, particularly non-circular or irregular shapes. This permits the labyrinth formation to adopt a shape which more closely conforms to the shape of the flange enabling more even thermal expansion and bolt load distribution across the flanges so as to further enhance the sealing performance of the flange joint.

Advantages of the invention may be summarised as follows: The use of a metallised gasket, such as HTA or spring steel facilitates removal during service by eliminating mica and/or graphite materials usually associated with the use of spiral wound gaskets; The joint is capable of withstanding high flange temperatures and pressure and may resist flange movement and distortion due to temperature variations during the operating cycle.

The joint enables robust sealing performance by providing multiple sealing points between the flanges.

The shape of the labyrinth may be adjusted to optimise sealing, enabling a more constant flange wall thickness, thereby minimising flange distortion.

The invention may find advantageous application in the joining of exhaust pipe sections, exhaust manifolds, turbo intake manifolds or exhaust catalysts, or any other components which require a sealed joint in a high temperature and pressure environment.

It will be appreciated that the present invention provides a joint having improved sealing properties compared with existing joints and enabling non-circular designs to be employed, thereby improving load distribution on the joint. The above-described embodiment represents a particularly advantageous form of the invention. Nevertheless, various modifications may be made to the joint and gasket disclosed herein without departing from the scope of the present invention, which scope is defined in the appended claims and

statements of invention hereinabove.

Throughout the description and claims of this specification, the words "comprise" and "contain" and variations of them mean "including but not limited to", and they are not intended to (and do not) exclude other moieties, additives, components, integers or steps.

Throughout the description and claims of this specification, the singular encompasses the plural unless the context otherwise requires. In particular, where the indefinite article is used, the specification is to be understood as contemplating plurality as well as singularity, unless the context requires otherwise. ii

Features, integers and characteristics described in conjunction with a particular aspect, embodiment or example of the invention are to be understood to be applicable to any other aspect, embodiment or example described herein unless incompatible therewith. All of the features disclosed in this specification, and/or all of the steps of any method or process so disclosed, may be combined in any combination, except combinations where at least some of such features and/or steps are mutually exclusive. The invention is not restricted to the details of any foregoing embodiments. The invention extends to any novel one, or any novel combination, of the features disclosed in this specification, or to any novel one, or any novel combination, of the steps of any method or process so disclosed.

Claims

CLAIMS: 1. A joint for joining and sealing first and second pipes of an exhaust system, the joint comprising: a first flange disposed at one end of the first pipe; a second flange disposed at one end of the second pipe; wherein the first flange includes a groove formed therein surrounding said first pipe and the second flange includes a ridge formed thereon for insertion into the groove, both the groove and the ridge being of corresponding non-circular shape; and a sealing member disposed in the groove and defining a channel for receiving the ridge so as to form a seal between the ridge and the groove, the sealing member being in the form of a gasket of flexible and/or resilient material shaped to locate within the groove and having a generally U-shaped cross section, with a base wall and first and second side walls, characterised in that the base wall of the gasket includes at least one base wall embossment and at least one of the side walls of the gasket includes at least one side wall embossment and the at least one base wall embossment and the at least one side wall embossment are different in height or depth, or the height or depth of at least one of the embossments varies along its length.
2. Ajoint as claimed in claim 1, wherein the groove and ridge are non-circular in shape.
3. A joint as claimed in claim 1 or claim 2, wherein the groove and ridge are substantially square, rectangular, triangular or irregular in shape.
4. A joint as claimed in any preceding claim, wherein the groove and ridge are shaped so as to conform substantially to the external shape of the respective flange.
5. A joint as claimed in any preceding claim, wherein the groove and ridge are shaped so as to: reduce or substantially eliminate non-uniform deformation of the flanges due to thermal expansion; and/or improve load distribution across the flanges.
6. A joint as claimed in any preceding claim, wherein at least one of the embossments extends continuously around the circumference of the gasket.
7. A joint as claimed in any of claims 1 to 5, wherein at least one of the embossments extends discontinuously around the circumference of the gasket.
8. A joint as claimed in any preceding claim, wherein each side wall includes at least one side wall embossment, and wherein the base wall embossment has a greater height or depth than the side wall embossments.
9. A joint as claimed in any preceding claim, wherein the gasket is formed from a high temperature alloy.
10. A joint as claimed in any preceding claim, wherein the gasket is arranged to be compressed or deformed when inserted into the groove so as to be self-retaining within the groove.
11. A joint as claimed in any preceding claim, wherein the groove and ridge are tapered so as to facilitate insertion of the ridge into the groove.
12. A joint for joining and sealing first and second pipes of an exhaust system, the joint comprising: a first flange disposed at one end of the first pipe; a second flange disposed at one end of the second pipe; wherein the first flange includes a groove formed therein surrounding said first pipe and the second flange includes a ridge formed thereon for insertion into the groove, both the groove and the ridge being of corresponding non-circular shape; and a sealing member disposed in the groove and defining a channel for receiving the ridge so as to form a seal between the ridge and the groove.
13. An exhaust system comprising at least one joint as claimed in any preceding claim.
14. A component for an exhaust system comprising a flange adapted for use in a joint as claimed in any preceding claim.
15. A vehicle having a joint, an exhaust system or a component as claimed in any preceding claim.
16. A flanged joint, a flange or an exhaust system constructed and arranged substantially as described herein with reference to the accompanying drawings.