An axial flow type cooling fan, comprising an upper casing, a lower casing, a rotor assembly, and a driving unit. The lower casing and the upper casing enclose an inner space. The rotor assembly is housed in the inner space and performs a rotational movement. The rotor assembly further comprises a plurality of blades, attached to a central shaft and having a peripheral ring, from which a peripheral rim extends outward. The driving unit has electric coils on the upper or lower casings and permanent magnets on the peripheral rim, causing the rotational movement of said rotor assembly. By the arrangement of these structural parts, an increased area of air flow and consequently increased air flow are attained, while drag and noise are reduced.

It is an object of the present teachings to provide a technique that rationalizes the structure of the brushless motor so as to save space in the power tool. According to the present teachings, a representative brushless motor utilized in a power tool may comprise a stator, a rotor and a cooling fan. The brushless motor is disposed within the power tool. The brushless motor is adapted to supply driving current to the stator to drive a tool bit of the power tool by rotating the rotor. The cooling fan is molded of a magnetic or conductive material so that the cooling fan also serves as a rotating position detector that detects the rotating position of the rotor with respect to the stator. Because the cooling fan may also have a function of rotating position detector of the rotor, the inner space of the power tool can be rationalized.

A circuit board fixing structure of a heatsink fan includes a housing having a pivot portion having a periphery provided with multiple poles. The housing is provided with a pair of positioning seats and a conducting wire receiving socket. The two positioning seats are formed with two insertion grooves. A circuit board is mounted in the insertion grooves of the positioning seats of the housing, and has a sensor and a conducting wire. The conducting wire may pass through the conducting wire receiving socket of the housing.

A pump or compressor for transporting a fluid comprises an impeller includes a plurality of impeller elements disposed for rotation to impart kinetic energy to the fluid. The impeller, which in one embodiment is an axial flow compressor, has an electrically conductive ring or other conductive members disposed along a rotary path of the impeller. An impeller driver includes a ring of magnetically permeable material extending in an arc proximate to the rotary path of the conductive portion of the impeller. The impeller driver acts as a motor stator with two core portions wound with electrically conductive coils for inducing a magnetic field in the ring and two electrically conductive pole portions spaced from the core portions. Alternating electrical current introduced to the coils imparts a rotary force to the electrically conductive ring of the impeller, causing it to transport the compressor working fluid.

An electromagnetic propulsion fan includes a hub and a plurality of fan blades coupled to the hub. The electromagnetic propulsion fan also includes a rim coupled to the fan blades such that rotating the rim causes the fan blades to rotate. The rim includes a plurality of magnets coupled thereto. The electromagnetic propulsion fan further includes a plurality of electromagnets in proximity to the rim, the electromagnets controllable to generate magnetic fields that interact with the magnetic fields of the magnets to cause the rim to rotated.