Patent attributes
An internal-combustion-engine supercharger includes a centrifugal compressor, a pre-compression flow path, a post-compression flow path, a bypass passage, and a control valve. The centrifugal compressor is disposed in an intake passage of an internal combustion engine and has an impeller to compress and discharge intake air using a radial centrifugal force generated by rotating the impeller. The intake air in the post-compression flow path is to be recirculated to the pre-compression flow path via the bypass passage. A connecting portion between the bypass passage and the pre-compression flow path is disposed at a position other than an extreme-bottom surface portion located at a lowest portion in a flow path section of the pre-compression flow path in a state where the internal-combustion-engine supercharger is installed in a vehicle. The control valve is disposed in the bypass passage to control a recirculation flow rate of the intake air.