| 摘要 |
PROBLEM TO BE SOLVED: To achieve high boost pressure under low flow rate by simplifying a system and narrowing a margin against a surge limit. SOLUTION: A supercharger 3 comprises a centrifugal compressor driven mechanically by an internal combustion engine 1. Based on an intake air flow rate Ga detected by an air flowmeter 8 and the number of revolutions of the supercharger 3, an opening degree of an air bypass valve 12 is controlled so that the compressor actually operates in the condition close to a surge limit. Since operating conditions of the compressor is detected with good response, a compressor operation line can be brought close to the surge limit without providing an excessively large margin. Therefore, higher boost pressure under low flow rate can be achieved.
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