Brushless motor

Abstract

When a brushless motor is used, only if the shapes of pole teeth of the stator core are changed, the cogging torque of the brushless motor can be increased while preventing increase in cost or reduction in assembly workability due to added components by apparently reducing the facing ratio between the pole teeth and the magnetic poles of the rotor magnets. A stator core (4) has a plurality of first pole teeth (4a1), a plurality of second pole teeth (4a2), and a plurality of third pole teeth (4a3) disposed circumferentially and projecting radially outward, the first pole teeth face rotor magnets (13) so as to be aligned with one of the magnetic poles of the rotor magnets (13) and have tooth tips (4a1a) symmetric with respect to a shaft line in a radial direction, the second pole teeth and third pole teeth are circumferentially disposed adjacent to the first pole teeth and have tooth tips asymmetric with respect to shaft lines in the radial direction, and a distance (t2) between the tooth tips of the second pole teeth and third pole teeth is smaller than a distance (t1) between the tooth tips of the first pole teeth and second pole teeth and the distance (t1) between the tooth tips of the first pole teeth and third pole teeth.

Description

technical field [0001] The present invention relates to a brushless motor used for, for example, HVAC (Heating, Ventilation, and Air Conditioning: Heating, Ventilation, and Air Conditioning) equipment and the like. Background technique [0002] For example, refer to image 3 The structure of the stator and the rotor of the external rotor type three-phase DC brushless motor will be described. The structure of the stator 1 will be described. The stator core 4 is a laminated core in which electromagnetic steel sheets are laminated. A plurality of pole teeth 4 a protrude radially outward from the annular core body. A coil (not shown) is wound around each pole tooth 4a. The stator core 4 is press-fitted and bonded to the outer periphery of a bearing housing (not shown) to be assembled. The bearing is embedded in the bearing housing. [0003] The rotor 8 is integrally assembled by caulking a cup-shaped rotor yoke 12 to a rotor hub fixed to one end of the rotor shaft. A ring-...

AI Technical Summary

Problems solved by technology

[0008] However, when an additional iron core is provided in addition to the stator iron core as in Patent Document 1, not only does the number of parts increase, but also an additional iron core other than the stator iron core needs to be attached to the housing, so the motor will be enlarged in the axial direction.

[0009] In addition, due to the additional parts of the motor, the cost may increase and the assembly workability may decrease.

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