| 摘要 |
The ventilation duct (7) has an air control unit (8) which has a successively widening front part (24) viewed in the duct flow direction (23), and a back part (25) which narrows successively when viewed likewise in the duct flow direction. This configuration forms a ring-shaped air through flow gap (27, 28, 29) with firstly a reducing and then an increasing through flow area. - The mouthpiece (16) causes the drive air currents (17, 18) to flow along an arc-shaped afr guide surface in the front part (24) outwards towards the air through gap narrowest parts (29). Thus, the drive air currents successively mix with the air (31) located on the upstream side around the air control unit (8) in the ventilation duct (7). |
