Engine exhaust manifold with thermal insulation - has annular air gap between pipe stub and wall of exhaust port bore

摘要

The cylinder head exhaust port (15) has an increased dia. sectin (15a). A step (16) between the two different dia. section (15a) forms an abutment for the exhaust pipe flange (17). The exhaust pipe dia. is less than that of the large dia. boring (15a) to form an air gap (22). The exhaust pipe is provided with a fitting flange (17) to bolt to the cylinder head. Sealing rings (20, 24) are fitted between abutment step (16) and fixing flange (17). The purpose of the air gap is to maintain exhaust gastemp. until reaching the after burner. The exhaust port could have a bore of equal dia. with the abutment step (16) and fixing flange (17). The purpose of the air gap is to maintain exhaust gas temp. until reaching the after burner. The exhaust port could have a bore of equal dia. with the abutment step formed round the exhaust pipe.