as shown in dashed line beginning from a predefined temperature because of the deformation of the memory element 30 such that heating of said area 10 will not take place any longer any desired meaningful combinations of these above described embodiments are also conceivable for example it is thus possible to provide a heat conducting element with a memory effect or e g to design it as a bimetal so that the contact between the hot area of the exhaust system and the cold area of the exhaust system is established at a low temperature the heat conducting element 32 provided with only one memory effect will be deformed beginning from a certain temperature as a result of which the contact between the heat conducting element and the cold or hot area of the exhaust system is interrupted the heat conduction is thus very extensively interrupted and the further introduction of heat from the hot area of the exhaust system into the cold area of the exhaust system is suppressed this combination of a memory element 30 is also analogously conceivable in an electrically heatable heating device 26 or the like such a heating device 22 may be arranged at the exhaust system 8 on the inside and or on the outside and or such that it passes through the walls of the exhaust system for example as shown in fig5 it is thus possible to arrange precisely such a heat conducting element 25 such that it passes through the wall of the exhaust system so that one end of the heat.