Gasket and heat shield assembly for a flanged joint

A heat shield and gasket assembly has three members including a first heat shield, a second heat shield, and a gasket. Each of the members has a flange portion and the flange portion of the gasket is sandwiched is between the flanges of the two heat shields. The flange portion of the gasket is thinner than the flange portions of the heat shields. The thinness of the gasket flange permits it to engage threaded assembly fasteners without compromising the thread integrity of the fasteners.

TECHNICAL FIELD

This invention relates to gaskets and heat shields, and high temperature fluid handling systems, such as engine exhaust.

BACKGROUND OF THE INVENTION

In automobile exhaust systems, a series of pipes are interconnected to conduct the flow of hot exhaust gases from the engine to the tailpipe of the automobile. The pipes consist of a manifold pipe and a pipe leading from the exhaust manifold, which are interconnected with flanged members.

This portion of the exhaust system transmits the exhaust gas directly from the engine to a pipe or passage leading to the catalytic converter. The flanged connection between these pipes radiates a large amount of thermal energy, which can be detrimental to some of the more sensitive components that are positioned near this joint. These components might include electrical wires and pipes carrying fluid for the engine.

The flanged joint is insulated from the surrounding environment by a heat shield that is attached directly to one or both of the flange members and is separate from the gasket, which is compressed between the flange members. The gasket member, of course, prevents the direct leakage of exhaust fumes as the exhaust gases pass through the pipe and the shield protects the environment.

The shield requires extensive machining through the flanges so that the shield might be attached thereto, The heat shield also requires additional work by the assembler to place the shield in the proper location, and if not securely fastened, can result in a rattle or other disturbing noise within the engine compartment.

It has been proposed to provide a single assembly for the heat shield and gasket. One such device is shown in U.S. Ser. No. 09/999,7975 filed Oct. 31, 2001, now U.S. Pat. No. 6,811,159, assigned to General Motors, one of the assignees of the present invention.

SUMMARY OF THE INVENTION

A heat shield for a hot gas exhaust pipe system defining a longitudinal axis according to an embodiment of the present invention comprises a first heat shield member having a first flange portion and a first heat shield portion. The flange portion lies in a plane and defines a first aperture for receiving therein an exhaust pipe of the system. The first heat shield portion defines a three dimensional configuration extending generally transverse to the flange portion in a first direction for surrounding and facing at least a portion of the received pipe outer surface in two different planes extending along and facing the longitudinal axis. The flange portion includes apertures for attaching the heat shield member to the system.

According to a further embodiment, the shield member comprises an arcuate element that extends about the axis.

According to a still further embodiment, the arcuate element forms a U-shaped channel facing a portion of the peripheral surface of the received pipe in a continuous curve.

DESCRIPTION OF AN EXEMPLARY EMBODIMENT

Referring to the drawings, wherein like characters represent the same or corresponding parts throughout the several views, there is seen inFIG. 1a heat shield and gasket assembly10having a first heat shield component12, a second heat shield component14, and a gasket assembly16.

As seen inFIGS. 2,3, and4, the heat shield12has a flange portion18and a heat shield portion20. The heat shield portion20flares outward from the flange portion18. The heat shield12is preferably made of stainless steel and has a thickness in the range of 0.38 mm to 1.10 mm. The thickness of the flange portion18of the heat shield12is determined in part by the rigidity required for the heat shield and gasket assembly10to provide the necessary protection. The flange portion18has two openings22and24.

As seen inFIGS. 5 and 6, the heat shield14includes a flange portion26and a shield portion28. The shield portion28flares outwardly from the flange26and does not have as an extensive length as the shield portion20of the heat shield12. The flange portion26has two openings30and32, which align with the openings24and22, respectively, of the flange18when the members are assembled. The shield14has a thickness considerably less than the thickness of the shield12. The shield14is preferably made from stainless steel with a thickness in the range of 0.22 mm to 1.10 mm. Depending in part by the rigidity required for proper protection within the system, it will also be apparent to those skilled in the art that the shield portion28is considerably smaller than the shield portion20. Therefore, the shield portion28need not be constructed from a blank having the same thickness as the shield portion20. In some assemblies, the need for two heat shields may not be required such that the heat shield14may be omitted.

As seen inFIGS. 7,8, and8A, the gasket assembly16has a flange portion34and a gasket member36. The gasket member36is secured in an opening38formed in the flange portion34. The opening38has a curled edge39, which is rolled around the gasket member36to retain the gasket member36in position. The gasket member36is preferably a mesh stainless steel ring, which is crushable during assembly to ensure proper sealing of the joint in which the heat shield and gasket assembly is used.

The flange portion34has two openings41and42. The opening41is substantially I-shaped and the opening42is substantially triangular. The openings41and42are aligned between the openings24,30, and22,32. The opening41has outer edges which are spaced to be substantially equal to the diameter of the openings22,24,30, and32. The triangular opening42has an outer dimension at the curved apexes thereof which is slightly less than the diameters of the openings in the flanges18and26. The flange portion34of the gasket assembly16is preferably made of stainless steel and has a thickness in the range of 0.18 mm to 0.22 mm.

FIG. 9is a depiction of the heat shield12, the gasket assembly16, and the heat shield14in an expanded view prior to assembly. When the members are assembled, as shown inFIG. 1, they are bonded together using conventional mechanical or chemical bonding processes. In the embodiment shown, the heat shield12, gasket assembly16and heat shield14are spot welded at approximately four locations to form the assembly10. As can be seen inFIG. 9, the openings22,41, and32are aligned at assembly and the openings24,42, and30are aligned at assembly.

After assembly of the heat shield and gasket10, it may be placed in a system, which includes an exhaust pipe44, as seen inFIG. 10. The exhaust pipe44includes a heavy flange member46to which is secured threaded fasteners48and50. The threaded fastener48passes through the openings24,42and30, and the threaded fastener50passes through the openings22,41, and32. The openings24,30,22, and32are significantly larger than the outer diameter of the fastener48. The openings41and42are shaped to engage the outer surface of the fasteners48and50as the exhaust pipe44is placed on the heat shield and gasket10.

The gasket assembly16, which contains the openings41and42, is, as pointed out above, made of very thin material. One of the reasons for the thinness is so that the openings41and42will engage the fasteners48and50with sufficient force to maintain the assembly10in position but without marring the outer diameter of the threads on the fasteners48and50.

Also, as pointed out above, the thickness of the flange18provides the rigidity for the assembly10. The members16and14provide gasketing and heat shielding for the assembly10. In particular, the gasket member36will be crushed between the flange46and a mating flange in the exhaust system, not shown. The collapsing of the gasket36prevents leakage of gaseous fluid between the flanges of the mating components. The heat shields20and28are positioned to reduce the amount of thermal energy that is radiated from the flange46and its mating flange, not shown.