Compressor recirculation into annular volume

A compressor for compressing gas, said compressor comprising:

• a compressor wheel (20) including a plurality of blades each of which includes a leading edge (24), a trailing edge and an outer free edge, said wheel being mounted for rotation within a housing,
• the housing including a compressor inlet (14) upstream of the compressor wheel and a compressor discharge (15) downstream of said compressor wheel,
• wherein the inlet comprises a channel wall (22) extending away from the compressor wheel in an upstream direction, and including an axially flattened, radially expanded cylindrical volume annularly open to the compressor inlet (14), axially upstream of the leading edge of the compressor wheel,
• said compressor further comprising a compressor return valve system comprising a compressor recirculation valve (CRV)(80) associated with a bypass duct providing fluid communication between the compressor discharge (15) and the to axially flattened, radially expanded cylindrical volume.

A low pressure EGR system for an internal combustion engine comprising:

• a compressor for compressing air to be supplied to the engine;
• a turbine stage including a turbine housing having an exhaust gas inlet for receiving exhaust gas from said engine, and an exhaust gas outlet, and a turbine wheel driven by the exhaust gas from the engine;
• an exhaust gas return duct by which exhaust gases to be returned to the engine are introduced to the compressor;
• and
• a boost air duct by which the air compressed in the compressor is supplied to the engine,
• wherein said compressor comprises:
• a compressor wheel (20) driven by the turbine wheel and including a plurality of blades each of which includes a leading edge (24), a trailing edge and an outer free edge, said wheel being mounted for rotation within a compressor housing and operable between choked flow and a surge line, the compressor housing including a compressor inlet (14) upstream of the compressor wheel and a compressor discharge (15) downstream of said compressor wheel,
• wherein the inlet comprises:
• an outer channel wall (22) extending away from the compressor wheel in an upstream direction and forming a gas intake portion in the upper inlet section,
• an inner channel wall (21) within the outer channel wall, comprising an inlet section (14) extending away from the compressor wheel upstream of the leading edges (24) of the compressor wheel and an inducer section (14a) downstream of the leading edges (24) of the compressor wheel, and
• an annular cavity (23) defined between the inner and outer channel walls, with an annular opening of the annular cavity (23) at the upstream end of the inner channel wall between the inner and outer channel walls, and
• wherein said exhaust gases to be returned to the engine are introduced via the exhaust gas return duct into the compressor annular cavity (23).