Patent ID: 8169117

Claim:
A brushless motor for a fluid pump, comprising: a stator core having a cross section in which six core shoes symmetrically protrude toward the center of a circle and six slots for winding are formed between the core shoes, wherein two core shoe grooves recessed in the longitudinal direction of the stator core the inner side of each of the core shoes are each formed with a center on a core shoe groove center line spaced apart at 8.4°±1° from a straight line passing through the center of the core shoe from the center of the stator core, and the width and depth of the core shoe grooves are 1.5 mm±0.5 mm and 0.53 mm±0.1 mm, respectively, a rotor core, which is inserted in the stator core, has rectangular permanent magnet holes that are formed in the circumferential direction from the center of the rotor core to be filled with four permanent magnets, symmetric bridge holes are formed at both ends of the permanent magnet hole, the bridge hole has a first wall that is spaced apart at 14.7°±2° from a straight line passing through the center of two adjacent permanent magnet holes from the center of the rotor core, a second wall that is connected to the first wall and spaced inside while maintaining a uniform thickness of 0.6 mm±0.1 mm from the outer circumference of the rotor core, a third wall that is connected to the second wall and spaced apart at 0.3 mm±0.1 mm from and in parallel with a straight line passing through the center of two adjacent permanent magnet holes from the center of the rotor core, and a fourth wall that is connected with the first wall and spaced apart at 0.35 mm±0.1 mm from and in parallel with a wall, which is closer to the center of the rotor core, of the permanent magnet hole, and the length of the fourth wall forming the bridge hole is set to 0.41 mm±0.1 mm.