BorgWarner's regulated three-stage (R3S) turbocharging system combines the benefits of two-stage turbocharging for high specific power output and parallel sequential turbocharging for best drivability. The innovative technology increases power density while improving fuel economy and reducing emissions for downsized diesel engines.
The first and the second charge air coolers 11, 12 are used for the intermediate cooling. The second and the third throttling elements 9 and 10, respectively, are situated at the input side and the output side of the second high-pressure compressor housing 5 b, which can be connected and disconnected. The second and the third throttling elements 9 and 10 are general valves for the shut-off as well as a bypass pipe. The bypass 7 connects the inlet of the second high-pressure compressor housing 5 b with the outlet of the second high-pressure compressor housing 5 b also in a connectable manner. On the exhaust gas side, a shut-off valve, i.e., a fourth throttling element 6, is situated in front of the inlet of the therefore connectable and disconnectable second high-pressure turbine housing 5 a in order to separate it from the exhaust gas flow. (Source: Bayerische Motoren Werke Aktiengesellschaft)