Abstract: A multistage turbocharging assembly is described. The multistage turbocharging assembly includes a first stage including a first turbine coupled with a first compressor via a first shaft. Further, the multistage turbocharging assembly includes a second stage including a second turbine coupled with a second compressor via a second shaft. The first compressor and the second turbine are arranged on a first side of the multistage turbocharging assembly and opposite to each other. The second compressor and the first turbine are arranged on a second side of the multistage turbocharging assembly and opposite to each other. Additionally, a method of operating a multistage turbocharging assembly is described.

Abstract: The means of sealing the compressor wheel with respect to the bearing housing includes an annular sealing element which forms a sealing boundary face with a shaft edge and to which a spring force is applied in the direction of the shaft edge. The external spring force neither compensates or amplifies the pressure forces acting on the sealing element, irrespective of the direction of the difference in pressure. As a result, the sealing of the oil space in the bearing housing of the exhaust gas turbocharger with respect to the shaft is not influenced, or is influenced only to a small degree, by the pressure fluctuations in the wheel back space of the compressor.

Abstract: The device serves for sealing a bearing housing of an exhaust-gas turbocharger, from which a rotor is led into a chamber of the turbocharger subjected to a mass flow. The device includes a sealing ring arranged in a groove of the rotor, a seat, arranged on the bearing housing and on which a pre-stressed sealing ring is secured by an outward-facing circumferential surface, and a radially extending separation gap, which leads annularly around the axis of rotation of the rotor and is defined by two superimposed sliding surfaces, the first of which is arranged on a first face of the sealing ring and the second of which is arranged on a first flank of the groove. In order to reduce a heat input into the sealing ring caused by lapping of the sealing ring during operation of the exhaust-gas turbocharger, a depression annularly around the axis is formed into the second flank of the groove. The depression is defined radially outwards by an annular body formed into the rotor.