TECHNICAL FIELD

The present invention relates to seals for sealing joints in automotive exhaust systems.

BACKGROUND ART

A portion of a typical automotive exhaust system is shown schematically in Fig. 1 of the drawings. This system usually comprises a header which in some instances is made of steel to provide low back pressure, rapid acceleration and high fuel economy. The system has a stepped down tail pipe section which may include a catalytic converter and a muffler. The juncture of the header manifold and tail pipe section usually includes a flange connection which is secured by bolts which compress a gasket at the interface of the flanges.

A typical gasket material is cork impregnated with asbestos. The confronting flange surfaces are rather narrow in a radial direction. By reason of this and also due to heat expansion and contraction in the exhaust systems, torsional shear forces are exerted on the gasket which produce cracking and associated exhaust leakage. Exhaust leakage in a passenger vehicle can be lethal. Furthermore, deterioration and failure of the gasket usually produces rattling and objectionable noise from the exhaust system. Most States now monitor exhaust systems and during periodic required inspections, will require replacement for leaky or noisy exhaust systems.

3 DISCLOSURE OF THE INVENTION

The present invention provides a seal particularly adapted for exhaust systems, which is characterized by novel features of construction and arrangement which overcomes the disadvantages of prior seals used for this purpose. The seal of the present invention provides a long lasting and secure means of sealing the junction between the header and exhaust pipe mating flange members.

To this end, the seal consists of an inner annular sealing ring-like member made of a deformable material, for example non-asbestos materials such as polyamids and a metallic outer spacer or retainer ring preferably made of steel, disposed between the flanges of the header and exhaust pipe and which circumscribes the annular ring member . In the relaxed state, the inner annular ring member is preferably of a larger axial cross-section than the axial cross-section of the metallic outer retainer ring, such as, perhaps two or three times thicker. In the relaxed state, the largest outer diameter of the inner annular member is slightly smaller than the bore diameter of the outer retainer ring. Further, the outer peripheral surface of the annular member is preferably contoured and includes at least a portion of a greater diameter than the header opening at the junction of the exhaust manifold and tail pipe section. In this manner when the annular member and retainer ring are placed between the flanges and the exhaust manifold and tail pipe section flanges are pressed together by conventional bolts, the annular member is deformed in a radial direction to press tightly against the inner bore of the retainer ring and the contoured outer peripheral surface of the annular member overlies the axial portion of the junction between the manifold section and tail pipe adjacent the flanges. This provides a large

surface contact with the annular member and the critical sealing area at the junction of the exhaust manifold and tail pipe section.

The installed seal of the present invention provides a large internal seal area that resists heat and pressure which develop in the exhaust system. Further, the internal back pressure acts on the seal in a manner to expand the sealing surfaces and aids in producing the large seal area, which inhibits escape of noxious exhaust gases and the like.

Further, the inner annular member is preferably made of a material which is capable of withstanding the temperature of the exhaust gases and is resistant to chemical deterioration to thereby preserve the integrity of the seal for a long period of time. As noted above, non- asbestos fibers such as polyamid fibers, manufactured by DuPont under the registered trademark

Kevlar, are suitable materials for the inner ring. Similarly, the outer ring is formed of metal, preferably stainless steel in order to resist. heat and corrosion.

In accordance with another embodiment of the present invention, a suitable adhesive is provided in the space or clearance between inner peripheral surface of the bore in the annular ring member and the outer peripheral surface of the flexible annular member to center the annular member with respect to the ring member so when the annular member is deformed to create the seal there between described above, the seal created is generally uniform with respect to the bore and side surfaces of the annular member. In other words, the deformed portions of the annular member by reason of the centering are insured to engage the opposing side surfaces surrounding the opening in the retainer ring.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other objects of the present invention and the various features and details of the operation and construction thereof are hereinafter more fully set forth with reference to the accompanying drawings, wherein;

Fig. 1 is a schematic illustration showing some of the parts of a typical automotive exhaust system including a header section and a tail pipe section;

Fig. 2 is an enlarged sectional view taken on lines 2-2 of Fig. 1;

Fig. 3 is an exploded perspective view of the elements comprising a seal made in accordance with the present invention;

Fig. 4 is an exploded side elevational view partly in section showing the parts of the seal and manifold and tail pipe section prior to assembly of the seal;

Fig. 5 is a side elevational view partly in section showing the seal in an assembled condition, the dot and dash portion shown in Fig. 1 ;

Fig. 6 is a typical prior art seal used for connecting the header and tail pipe sections;

Fig. 7 is an enlarged fragmentary view of the assembled seal shown in the dot and dash circle of Fig. 5;

Fig. 8 is perspective view of a another embodiment of a seal made in accordance with the present invention;

Fig. 9 is an enlarged fragmentary sectional view taken on lines 9-9 of Fig. 8;

Fig. 10 is a front elevational view of still another modified pre-assembled header and tail

pipe seal;

Fig. 11 is an enlarged fragmentary sectional view taken on lines 11-11 of Fig. 10 showing details of the pre-assembled gasket and steel supporting ring in an non use mode;

Fig. 12 is a fragmentary sectional elevational view showing the pre-assembled seal of Figs. 10 and 11 clamped between the header flange and the tail pipe flange also shown fragmentarily;

Fig. 13 is a front elevational view of another embodiment of a pre-assembled seal for use between the header and tail pipe connection;

Fig. 14 is an enlarged exploded side elevational view of the steel supporting ring, shown in section, and the deformable gasket shown in full prior to positioning the gasket centrally within the bore of the steel supporting ring, as shown by the dot and dash outline of the gasket;

Fig. 15 is an enlarged fragmentary sectional view taken on lines 15-15 of Fig. 13 showing details of final assembly;

Fig. 16 is a front elevational view of still another embodiment of a pre-assembled seal for use between the flanged ends of the header and tail pipe connection;

Fig. 17 is an enlarged fragmentary sectional view taken on lines 17-17 of Fig. 16 showing details of the continuous, chevron shaped steel strip wound in a circular configuration and including a non-asbestos filler material and details of the means for retaining the deformable continuous steel wound gasket centrally within the steel supporting ring; Fig. 18 is an exploded fragmentary isometric view showing portions of the two elements comprising the continuous steel wound gasket shown in Figs. 16 and 17;

Fig. 19 is an enlarged fragmentary sectional view showing the seal of Fig. 18 clamped

between the end flanges of the header and tail pipe;

Fig. 20 is a front elevational view of another modification for a seal comprising a steel supporting ring and a pre-assembled gasket formed from a deformable powder metallic material; and

Fig. 21 is an enlarged fragmentary sectional view showing details of the steel supporting ring and means for retaining the powder metallic gasket.

BEST MODE FOR CARRYING OUT THE INVENTION

Referring now to the drawings and particularly to Fig. 1 thereof, there is shown schematically a typical automotive exhaust system generally designated by the numeral 10 which includes a header section 12 and a tail pipe section 14. The tail pipe section 14 may include a catalytic converter and a muffler downstream of the header. The header section 12 and tail pipe section 14 have circumferentially extending radially outwardly directed flanges 20 and 22 including a series of circumferentially spaced aligned bolt holes 20a and 22a for bolt and nut fasteners 25 and 27 respectively.

This junction of the two flanges 20 and 22 is sealed by a flat ring-like gasket 28 prior to the present invention in the manner illustrated in Fig. 6. This gasket type seal presents disadvantages and drawbacks discussed above. These disadvantages may be summarized by the fact that these seals do not withstand the torsion loads and other conditions that tend to cause leakage paths so that the gasket 28 will often fail prematurely creating noise and potential health problems.

The seal of the present invention is characterized by novel features of construction and arrangement facilitating a tight long term seal between the flanges of the sections of the exhaust system described above. The seal of the present invention provides a large effective surface area sea at the juncture of the flanges.

More specifically, the seal of the present invention comprises two annular sealing members, an inner annular sealing ring like member 40 made of a deformable material, such as non-asbestos fibers admixed with steel wire, and an outer spacer or retainer ring 42 preferably

made of steel circumscribing the annular ring member 40 and radially spaced therefrom to define a circumferentially extending gap G. The bore 44 of the outer retainer ring 42 is preferably circular and of a diameter D, slightly greater than the maximum diameter D of the inner annular ring member 40 in the relaxed state. Further, the inner annular ring member 40 is preferably of a larger axial width W greater than the thickness T of the outer retainer ring 42.

In the present instance, the annular ring member 40 has a generally cylindrical bore 46 and has a contoured outer peripheral surface 48, consisting in the present instance of two circumferentially extending tapered frusto conical outer faces 48a and 48b connected by a short generally cylindrical center section 48c. In this manner, the inner edge 60 defined by the flange 20 of the manifold section 12 and the inner edge 62 of the flange 22 defined by the tail pipe section 14 engage at about the mid point of the opposing tapered frusto conical faces 48a and 48b of the inner annular ring member 40 when the seal is positioned between the flange members 20 and 22 as shown in Fig. 4.

Thereafter, when the flanges 20 and 22 are drawn together by tightening the bolts 25 to a position where they are spaced apart by the thickness T of the metallic retainer ring 42, the inner edges 60 and 62 press against the opposing tapered faces 48a and 48b to deform the annular ring member 40 so that the seal presses tightly at the junction of the parts in the manner shown in Fig. 7. Note that the material of the annular ring member 40 overlies and presses tightly against the circumferentially extending surfaces adjacent the edges 60 and 62. Thus, the seating of the ring member 40 and deformation thereof as described above, produces two (2) circumferentially extending axially directed seal areas 60a and 62a engaging the internal surfaces of the header section 12 and exhaust section 14 in the manner best illustrated in Fig. 7 and a

radially outwardly directed bead 40c engaging between the flanges and tightly pressed against the retainer ring 42.

The following is an example of a seal in accordance with the present invention for a typical automotive exhaust system wherein the header 12 has an inside diameter D2 of 2.875 inches, as does the portion of tail pipe 14 at flange 22.

REF. LETTER DEFINITION MEASUREMENT

D Outer diameter of inner annular 3.0 inches sealing ring member 40

Dl Inner diameter of the outer retainer 3.625 inches ring member 42

D2 Inside diameter of header section 12 2.875 inches adjacent to exhaust section 14

D3 Pitch circle of bolt fasteners 25 3.875 inches equally spaced from each other as shown on outer retainer ring 42 in Fig.2

D4 Inner diameter of inner annular sealing 2.50 inches ring member 40

D5 Generated outer diameter of outer 4.25 inches retainer ring 42

Of course, different exhaust systems have different sized headers and tail pipes or exhaust pipes, and the seal of the present invention will need to be sized to accommodate those dimensions. Most automobile exhaust systems can be sealed by the present invention using one of about three general sizes.

The installed seal of the present invention provides a large internal seal area that resists the effects of heat and pressure which develop in the exhaust system. Further, the internal back pressure acts on the seal in a manner to expand the sealing surfaces and aids in producing the large seal area, which practically eliminates the escape of noxious exhaust gases and the like. There is shown in Figs. 8 and 9 another embodiment of seal in accordance with the present invention. The basic elements of the seal which are the same as the previously described embodiment have been assigned the same reference numeral with a prime (') superscript. Thus, the seal comprises two (2) annular sealing members, an inner annular sealing ring-like member 40' made of a deformable material such as non-asbestos fibers mixed with steel wire and an outer spacer or retainer ring 42' made of steel spaced therefrom to define a circumferentially extending gap G'. The bore 44' of the outer retainer ring 42' is circular and of a diameter D,' slightly greater than the maximum diameter D' of the inner ring member 40' in the relaxed state. Further as illustrated in Fig. 9, the annular member 40' is of generally trapezoidal cross section and has an outer peripheral surface of a width W greater than the thickness T' of the retainer

In accordance with this embodiment of the invention, means is provided for supporting the inner ring member 40' in the pre-assembled state to the outer retainer ring 42' prior to assembly in a manner to permit deformation of the ring in the manner described above upon assembly at the juncture of the manifold section 12 and tailpipe section 14. In the present instance, the means comprises an adhesive applied on either side of the gap G' to form circumferentially extending beads or rings R- as illustrated in Fig. 9. This supports the ring member 40' in the desired centered position relative to the rigid retainer ring 42'. Further,

when the sealed assembly is installed and the bolts are tightened, the beads of adhesive R, adhesive becomes part of and contributes to providing an effective seal with the annular surfaces on either side of the retainer ring 42' adjacent the bore in the manner shown in Fig. 7.

The embodiment of the invention shown in Figs. 10-12 inclusive is generally similar in overall instruction and configuration to that described previously and shown in Figs. 8 and 9 and accordingly the parts have been numbered with the same last two digits except in the one hundred series. Thus, the basic elements of the seal assembly include an inner annular sealing ring like member 140 made of a deformable material and an outer retainer ring 142 preferably made of steel circumscribing the inner ring 140, the two being supported in the preassembled state by beads of adhesive R,. As illustrated in the drawing, this supports the ring member 140' in the desired centered position relative the rigid retaining ring 142. In the present instance, a circumferentially extending groove 141 is provided in the bore of the retaining ring 142. As illustrated, the groove 141 is of an axial length L _a less than the width W _s of the seal surface 48 _c , so that when the seal is installed and compressed laterally, the seal material forms a radially outwardly extending rib 143 which further locks the parts in place.

There is shown in Figs. 13 - 15 still another embodiment of seal assembly in accordance with the present invention. The components and the basic arrangement of the seal are similar to that described in connection with principal embodiment shown in Figs. 1-5 inclusive and Fig. 7 and accordingly the parts in this embodiment are designated in the two hundred (200) series with the last two digits being the same as the numerical designations for the principal embodiment. Thus, the seal assembly includes two annular sealing members, an inner annular sealing ring 240 made of a deformable material such as non-asbestos fibers mixed with steel wire

and an outer spacer or retainer ring 242 made of steel. The bore 244 of the outer retainer ring 242 is generally circular. In the present instance, the outer diameter D' of the inner ring member in the relaxed state is equal to or slightly less than the diameter Dl ' of the bore 244. In accordance with this embodiment of the invention, means is provided for supporting the inner ring member 240 so that it is centered in relation to the outer retainer ring 242, in the preassembled state, to permit deformation of the ring in the manner shown, for example, in Fig. 14. To this end the outer ring 242 is deformed by swaging at a plurality of circumferentially spaced locations to define radially inwardly directed projections 260 which define a circle C having a diameter D _c slightly less than the diameter D' of the deformable seal member 240 and thus support the inner member 240 in the centered position by a friction or pressed fit at the projection locations 260.

There is shown in Figs. 16 - 19 still another embodiment of seal assembly in accordance with the present invention. The basic components of the seal are similar to that described in the previous embodiments. In this embodiment the parts are designated by the three hundred (300) series. Thus, the basic elements of the seal assembly include an inner sealing ring member 340 made of a deformable material and outer retainer ring 342 preferably made of steel circumscribing the inner ring 340. In this embodiment the bore of the outer retainer ring 342 is generally circular and has circumferentially extending groove 341 facing radially inwardly in the bore. The inner annular sealing member 340 in the present instance, comprises a continuously wound member 344 made of steel having a chevron configuration as shown in Figs. 17 and 18 including a radially outwardly directed projection or rib 346 which in the relaxed state snaps

loosely into the groove 341 in the outer retaining ring 342 and which compressed provides a tight locking engagement of the inner ring member relative to the rigid support ring. The inner ring member 340 also deforms to provide side seals in the manner indicated in Fig. 19. The continuously wound steel coil also includes an inner layer 348 made of a non-asbestos material. In accordance with the embodiment of the invention shown in Figs. 20 and 21 , the gasket

440 is made of a fusible powdered metal composition, such as KAFITE III (E 7488) sold by Quin-T Corporation of Erie, Pennsylvania, and the retaining ring 442 is made of a rigid metallic material such as steel. The shape of the gasket is generally similar to the gaskets previously described and is generally trapezoidal having a top wall which is of a width greater than the width of the retaining ring so that when it is assembled, the gasket deforms to provide a seal against the opposing inner and outer faces of the retaining ring 442 adjacent the annular bore in the retaining ring. In the present instance, the retaining ring 442 is provided with a number of swaging indentations to hold the gasket in place in the retaining ring in the manner shown in Fig. 21. A variant on the embodiment of the invention shown in Figs. 20 and 21 is to make both the gasket and retaining ring of a metallurgical composition and as an integral assembly. After fusing under heat and pressure, because of its relative thinness, the retaining ring is sufficiently rigid so that it will not deform upon normal pressures exerted between the confronting faces of the header and seal assembly. However, the gasket, being thicker, will deform to provide the axial and radial seals in the manner shown and described previously. A suitable composition for forming both the retaining ring and the deformable gasket is a fusible powdered metal composition, such as KAFITE III identified above.

Even though a particular embodiment of the invention has been illustrated and described herein, it is not intended to limit the invention and changes and modifications maybe be made therein within the scope of the following claims: