| 摘要 |
The internal absorbent layer (9) of the casing delimits an internal volume (10) around the drill (1), which volume is divided on either side of the exhaust orifice (3) by two transverse partitions (13A, 13B) into three successive expansion chambers (11A, 11B, 11C) between the exhaust orifice (3) and the outlet opening (12) to the air outside the casing. |
