Abstract: A radial fan that includes a fan wheel, which can be rotated about an axis and which comprises a base plate and airfoils protruding from the base plate, wherein the airfoils each comprise an upstream edge in a first spacing (r1) from the axis and a downstream edge in a second spacing (r2) from the axis, and an end wall, which together with the base plate, delimits a flow channel in which the airfoils engage. The cross-sectional area (A) of the flow channel between the upstream edge and the downstream edge passes through a maximum in a third spacing (r3) from the axis. The difference between a fourth spacing (r4) and a fifth spacing (r5), at which the cross-sectional area (A) in each case assumes nearest adjacent minima to the maximum, is at least half of the difference (r2?r1) between the first and the second spacing.

Abstract: A radial fan that includes a fan wheel, which can be rotated about an axis and which comprises a base plate and airfoils protruding from the base plate, wherein the airfoils each comprise an upstream edge in a first spacing (r1) from the axis and a downstream edge in a second spacing (r2) from the axis, and an end wall, which together with the base plate, delimits a flow channel in which the airfoils engage. The cross-sectional area (A) of the flow channel between the upstream edge and the downstream edge passes through a maximum in a third spacing (r3) from the axis. The difference between a fourth spacing (r4) and a fifth spacing (r5), at which the cross-sectional area (A) in each case assumes nearest adjacent minima to the maximum, is at least half of the difference (r2-r1) between the first and the second spacing.

Abstract: An electronically commutated motor has at least two winding phases (112, 114) which are wound together or otherwise inductively coupled. Current in each phase is controlled by a respective power transistor (124, 128). An integrated circuit controller (146) receives signals from a Hall sensor (118) and generates rotor position output signals (OUT1, OUT2) which are oppositely phased and are applied to the bases of the respective power transistors (124, 128) so that the power transistors never both conduct at the same time. Further, a pair of latching transistors (162, 172) and a pair of base drain resistors (164, 174), connected to respective bases of the power transistors (124, 128) are provided, in order to assure “soft” switching of the power transistors at low RPM, yet prompter switching and higher efficiency at high RPM. These additional components also ensure a sufficiently long current gap between switch-off of one power transistor and switch-on of the other power transistor.