A coaxial cable connector system is provided. A inexpensive, compact bidirectional optical communications module can be offered with reduced interference between outgoing and incoming light, especially, interference due to internally scattered light. The charge air comprises exhaust gases which are conducted to the charge air cooler, with an adjustable exhaust-gas recirculation rate, from an exhaust tract of the internal combustion engine. The temperature estimating device estimates a first exhaust gas temperature on a downstream side of the exhaust gas purifying device through a transfer function, which is expressed by a plurality of identical first-order lag elements, based on a second exhaust gas temperature on the upstream side of the exhaust gas purifying device sensed by the exhaust gas temperature sensor. The case body is rotatable along an axis which is in alignment with the hinges. In this cable, a neutral conductor or a screening is arranged only outside of the cryostat, and is formed by normally conductive material which surrounds the cryostat as a common neutral conductor, where an insulating material is arranged between this neutral conductor and the cryostat.