| 摘要 |
A shroud (10; 40) for use in apparatus incorporating cyclonic dust separation means for separating dirt and dust from an airflow, (10; 40) comprises a perforated portion (14; 44) having a multiplicity of perforations (30; 46) for allowing the airflow to pass therethrough. According to a first aspect of the invention, the upstream edge of each perforation (30) meets the upstream surface (28) of the shroud (10) at a sharply defined angle. According to a second aspect of the invention, the perforated portion (14) has a lower edge (16) and a lip (18) depending therefrom, the lip (18) comprising a parallel-sided portion (34) having an inclined distal end and a step (38) formed radially inwardly of the parallel-sided portion (34) and at the proximal end thereof. According to a third aspect of the invention, the perforated portion (44) is frusto-concial in shape and the diameter (d) of each perforation (46) is substantially 2.2mm. Each of these aspects improves the performance of the dust separation apparatus in which the shroud (10; 40) is utilised. <IMAGE>
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