GB1432293A - Motor vehicle and exhaust pipe therefor - Google Patents

Abstract

1432293 Vacuum insulated pipe NISSAN MOTOR CO Ltd 27 Feb 1974 [2 March 1973] 8966/74 Heading F2P [Also in Division F1] An exhaust pipe for a motor vehicle comprises an inner tube 31 which conducts exhaust gas and an outer tube 32 surrounding the inner tube with a sealed and evacuated annular space 33 between them. The width of the space 33 is determined by the exhaust gas temperature and dimensions and material of inner tube 31. The exhaust pipe may be constructed by welding the ends 34, Fig. 2, of the outer tube 32 which can be made either of stainless or ordinary steel to the inner tube 31 which may be made of stainless steel and then removing air from the annular space 33 thus formed through a vent in the outer wall. Flanges 35 can be attached to the ends of the inner tube so that the exhaust pipe can be connected to other parts, e.g. the exhaust manifold of the motor vehicle exhaust system. Damage to the outer tube especially in the regions where it is welded to the inner tube due to the unequal expansion of the tubes can be prevented by forming at least one circumferential groove 36, Fig. 3, around to outer tube 32. The heat insulation provided by the evacuated space may be improved by a. heat reflective coating 37 of, for example, chromium or aluminium on the inside surface of the outer tube which reduces the heat transferred by radiation from the inner tube and thus protects the vehicle body against unwanted heating caused by the exhaust gases.