Patent ID: 8080907

Claim:
A rotor of a brushless (BL) motor, comprising: a concavo-convex portion formed around a rotary shaft; a first high-strength engineering plastic member formed by injection molding on the concavo-convex portion; a sound-absorbing resin element formed by injection-molding around the first high-strength engineering plastic member; a ring-shaped magnet disposed on the outer side of the sound-absorbing resin element; and a second high-strength plastic member formed by injection molding between the sound-absorbing resin element and the ring magnet to prevent damage of the ring-shaped magnet due to the thermal expansion of the sound-absorbing resin element; wherein a plurality of concavo-convexes are formed on the outer circumferential surface of the first high-strength engineering plastic member to increase the bonding force between the first high-strength engineering plastic member and the sound-absorbing resin element, and indented grooves are formed on the inner circumferential surface of the ring-shaped magnet to be engaged with protrusions formed on the outer circumferential surface of the second high-strength plastic member to increase the bonding force between the second high-strength plastic member and the ring-shaped magnet.