High pressure ratio turbocharger

A turbocharger system for internal combustion engines, comprising:

• means forming a turbine adapted to be driven by exhaust gas from an internal combustion engine;
• and
• means forming a high-pressure compressor driven by said turbine means, said high-pressure compressor, comprising:
• a plurality of stator blades, and
• a radial-compressor stage formed by a plurality of rotating radial-compressor blades, said radial-compressor blades being driven in rotation by said turbine means to deliver a flow of air at high pressures to an internal combustion engine,
• said plurality of stator blades being movable to vary and adjust compressor output characteristics, said turbine means comprising:
• a turbine wheel having a central core and a plurality of outwardly extending vanes, said turbine wheel being rotatable about a central axis;
• a meridionally divided volute for exhaust gas surrounding said turbine wheel, said meridionally divided volute including means for defining first and second volute passageways having a divider wall therebetween, said first and second volute passageways defining first and second turbine inlet openings permitting exhaust gas from said first and second volute passageways, respectively, to act on the outwardly extending vanes of said turbine wheel, said first volute passageway directing exhaust gas into said turbine wheel substantially radially of said wheel and said second volute passageway directing exhaust gas into said turbine wheel substantially axially of said wheel;
• closure means movable between a first position permitting exhaust gas to flow from both said first and second volute passageways to act on the outwardly extending vanes of said turbine wheel during periods of high-engine speed, and a second position permitting exhaust gas to flow from only said second volute passageway to act on the outwardly extending vanes of said turbine wheel during periods of low-engine speed;
• and
• a control connected with one or more sensors on the internal combustion engine to operate said stator vanes of the compressor means and the closure means to operate said turbocharger to match the turbocharger air output with the air requirements of the internal combustion engine throughout its operating range.