| 摘要 |
A miniature axial fan (Figs 3, 4) has a central, impeller-driving electric motor 6, an impeller 2 secured to the rotor of the motor and surrounded by a casing having an inner wall 3 which is cylindrical for a substantial portion of its length and then diverges in the flow direction towards the outflow end A. The drive motor 6 is carried by webs, 5 and the number of impeller blades 7 differs from the number of webs 5. In the case of an impeller diameter at most 60 mm, the fan blades 7 (Fig 7) are irregularly distributed and constructed in such a way that adjacent the outflow end they have a large setting angle of 70 to 90 DEG , and, in a radial plan view on the rotation axis, the curvature of the blades from the inflow-side is initially limited and then becomes more marked towards the outflow-side blade edge. The webs 5 and casing (1) may be integrally formed with a flange 13 and tube (17) (Fig. 1) by moulding, for supporting the bearings for a shaft 12 of the motor rotor. The flange 13 may house commutator components for the motor 6. Various alternative motor and impeller hub constructions are disclosed as are further structural details of the moulded casing. A method of making the impeller blades is also referred to. <IMAGE>
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