Compressor bypass valve for sequental supercharging

A compressor bypass valve (6) comprises a valve housing (1) including a compressor bypass passage and a displacement body (2) disposed in the housing. The body includes two displacement parts (3, 4); first part is facing an upstream side of the housing. The first part is movable relative to the housing and operative to open and close the passage. The valve also comprises a seal (7) and a spring (9).