① Brushed Dc Gear Motor. In this type of motor, rare-earth materials are bonded to a cylinder block, and the disc windings made of enameled copper wire are placed inside the cylinder block to form the rotor. The dc gear motor 12v 24v phase is adjusted by a mechanical commutator. The mechanical commutator adjusts the voltage phase by friction between fixed carbon brushes and rotating copper commutation surfaces.
During use, the brushes wear down continuously, and the motor's lifespan is unlikely to exceed 1000 hours. Furthermore, due to the high motor speed, a two-stage gear reduction is necessary, which introduces two problems: increased noise and significant efficiency loss. The rated efficiency of the dc brush gear motor after reduction is often only 68%–72%. Since the battery capacity used in electric bicycles is limited, typically 3.7V-24V, low motor efficiency will increase power consumption and affect the driving range.
② Brushed dc gear motor. This type of motor uses printed copper foil as the windings, reducing the motor's weight. Because these dc gear motors 24V are manufactured entirely on automated production lines, the manufacturing process is reliably guaranteed, resulting in a lifespan of up to 1000 hours, a significant reduction in noise, and an efficiency increase to 72%–76%. However, these motors produce a high-frequency "humming" noise, and even with gear reduction, their efficiency remains unsatisfactory. The use of brushed commutators limits further lifespan improvements.
③ Brushed DC mini gear motor. These high torque dc gear motor achieve an efficiency of 74%–78% by pressing pre-wound copper wire into a new type of winding. While still widely used by electric bicycle manufacturers, their efficiency, noise, and lifespan limitations remain issues that require improvement.